Luminous Landscape Forum
Site & Board Matters => About This Site => Topic started by: fredjeang on July 17, 2011, 08:06:36 pm
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This is an extensive evaluation that I had interest and pleasure to read.
Thanks to Michael and friends for the work done.
I completly agree with MR that the "Foveon look" reminds me more of an Agfa than a Kodachrome. Anyway,
I had some of their products (and still own a compact DP that I hardly use) and yes, more or less I was expecting what I read except that boost in reso,
it completly matches my past experiences with the SD line.
Nothing really new under the sun, the samples match, I see the same goodies and no-goodies but it seems that the body is more acheive on this model in terms of quality.
By the way, the palette is not a mistake, this is the same with previous models.
For the passionate amateur who print a lot it could be a nice option if it wasn't so expensive; for the pro, just pass your way and go to the bar. It's cheaper.
Good review.
PS: I had a good laugh when at one point of the review I saw all the cautions, care and choosen words Michael displayed when it comes to not irritates the scientists about the differences between numbers and human perception and the spirit his reviews are made. Pure art of social journalism. Is it that bad in the mailbox?
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I found these sentences most interesting:
"Let's be frank. The SD1 is ridiculously overpriced. It's a decent APS-C camera with mid-level built quality; at about the $1,000 level. It has neither the features nor specifications of a Pro camera such as a Nikon D3x or Canon 1Ds MkIII, let alone a 5D MKII or Sony A900. And with new 30+ Megapixel versions of these three company's flagships coming in the months ahead, along with not having video, no Live View, no tethering, and no pro support program, the SD1's price is simply untenable.
Know anything that we don't?
Cheers,
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And with new 30+ Megapixel versions of these three company's flagships coming in the months ahead
I thought that was just stating the obvious....
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Hi,
Just some observations:
1) Going from 24 to 30 MPix is a minor step
2) I'm not really sure that it is obvious that 30+ MP cameras arrive this year, my guess may be just before Photokina 2012
Best regards
Erik
I thought that was just stating the obvious....
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Hi,
Just some observations:
1) Going from 24 to 30 MPix is a minor step
2) I'm not really sure that it is obvious that 30+ MP cameras arrive this year, my guess may be just before Photokina 2012
Best regards
Erik
Perhaps I should have said 'The Inevitable..." ;D
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I don't think that the coming 30MP ish models from CaNikon are the real problem with this camera.
The potential people who would be interested in it are basically (IMO) looking for a different proposal-look in a dslr wrapper for their printings
or precisely an alternative to the CaNikon dslrs, wich was my case. I bought Sigma in the past because I was looking for a different sensor's approach,
but not as a replacement to the pro line Canons, because it's not. It was like adding another palette in my tools.
Then, as I hardly print now (or never), the strengh of that formula wich resides in the printing output didn't make any sense to me, because the body is
absolutly unusable in a professional workflow.
The real issue with this camera is the price. It simply does not have the value Sigma is asking for. It should be a 2000 euros body and that's where all the dilema is.
I've stressed many times that the Foveon is a great tech but in the wrong hands. Sigma is a too small company to develop properly all the potential of the sensor.
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The conclusion seemed to be buy an A900 and have the AA filter removed.. ;D ;D ;D
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Hi,
Just some observations:
1) Going from 24 to 30 MPix is a minor step
2) I'm not really sure that it is obvious that 30+ MP cameras arrive this year, my guess may be just before Photokina 2012
Best regards
Erik
Well, the key is the + at the end of 30+. current rumor for Sony is 39mp. At that fine of pixel pitch, the AA filter may not be necessary, so even if it exceeds lens resolution, a big improvement.
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Wayne,
A good point. On the other hand the Alpha 55 correspond to 36 MP when recalculated to full frame.
I have noticed some aliasing/moiré on my Alpha 55 so I guess that it may lack AA-filter.
As a side note I did a comparison of Michael's samples upscaled to same size (with Pentax 645D as reference), in my view the picking order was quite clear:
Pentax
Sony A900 and Leica M9
Sony A55 and Sigma SD1
Now, those images were intended for display on the web, not really optimal for this kind of comparison. I also noted that the picking order may be affected by viewing distance.
In general I'd suggest that increasing resolution is a good thing. Aliasing is reduced, AA-filtering is always optimized for pixel pitch, so smaller pitch means weaker filtering. You are right that the AA-filter may be removed, but my sample from the Alpha 55 indicates that artifacts can arise. By the way, that image is taken with 400/5.6 and 1.4x extender at f/10, I did not really expect moiré but I think it's quite clearly there.
The Foevon sensor would of course not have any color moiré, but it could still have some jaggies and false resolution artifacts. An example of that is clearly visible in DP-Review test of the DP2, also enclosed. We can see that the line pattern turns mush around 1800 but shows fake resolution at 2000 and up, this is an example of contrast inversion. It is possible that the effect is not visible on normal pictures.
Best regards
Erik
Well, the key is the + at the end of 30+. current rumor for Sony is 39mp. At that fine of pixel pitch, the AA filter may not be necessary, so even if it exceeds lens resolution, a big improvement.
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Thoughtful and well-written review. One question that came to mind for me since the Foveon technology has existed for some years prior the Sigma acquisition (and I assume they own the intellectual property now) is whether Canon & Nikon evaluated it and decided that the potential benefits were not worth the development costs. I don't know the full history here and it maybe that they did. I chuckled at the 1970s Agfachrome statement since in my exuberant youth I shot rolls and rolls of the stuff thinking how great it was. When I started to digitize all my slides a couple of years ago, I awoke from the stupor to realize that it really wasn't as good as Kodachrome.
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Thoughtful and well-written review. One question that came to mind for me since the Foveon technology has existed for some years prior the Sigma acquisition (and I assume they own the intellectual property now) is whether Canon & Nikon evaluated it and decided that the potential benefits were not worth the development costs. I don't know the full history here and it maybe that they did.
Canon at least has hedged their bets (http://www.luminous-landscape.com/forum/index.php?topic=55691.0).
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I was hoping to see Michael make some large 30x45 ish prints from each system to see how the SD1 held up to the others.
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I was hoping to see Michael make some large 30x45 ish prints from each system to see how the SD1 held up to the others.
Perhaps it didn't come across clearly in the review, but we did that. The results were exactly as Michael described. The 645D pulled clearly ahead, to my eye the Leica was in second place, and the A900 and SD1 were very close with the A55 bringing up the rear by a small margin.
- N.
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Thanks for the great review. Even if Sigma slashes their price by half it won't be good enough. I wonder why they went into production. They had to know this (the costing issue) would happen, right?
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Hi,
My impression is that the problem is not the cost but the value. The cost is similar to the Nikon D3X and the Leica M9. The value is in the eyes and hands of the beholder. Both the M9 and the SD1 lack live view for instance. The Sigma may lack the solid build of the Nikon D3X and the M9. Also, Sigma may lack some of the high quality lenses available for Nikon, Canon and Leica.
In general, a larger sensor has advantages. A larger sensor delivers more photons to the sensor and the sensor can hold more electron charges. A larger sensor is also able to deliver more MTF to the sensor than a smaller one, at least if pixel count is the same.
To some photographers image quality is all that counts. If the Sigma SD1 really delivers it may be perfectly enough for those customers. On the other hand I'm quite skeptical that Sigma SD1 can really keep up with top of the crop full frame DSLRs.
Best regards
Erik
Thanks for the great review. Even if Sigma slashes their price by half it won't be good enough. I wonder why they went into production. They had to know this (the costing issue) would happen, right?
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Perhaps it didn't come across clearly in the review, but we did that. The results were exactly as Michael described. The 645D pulled clearly ahead, to my eye the Leica was in second place, and the A900 and SD1 were very close with the A55 bringing up the rear by a small margin.
- N.
The only reason I can surmise for the high price is the fact that there is no other crop-format camera on the market with such 'effectively' high resolution. 30mp for a cropped format DSLR is impressive, hence the impressive price.
The A900 is a heavier camera and lacks the advantages of the cropped format, such as better DoF at the same aperture, and lighter lenses when such lenses are designed for the cropped format, and lighter lenses always in relation to an 'effective' focal length, even with full-format lenses.
The Sigma SD1 is offering a level of performance, in certain respects, that no other camera currently available is able to offer. That's the reason for the high price.
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Hi,
Yes, there are some advantages to cropped format. On the other hand there may not be so many really high quality lenses optimized for APS-C, especially not with Sigma bayonet. The Sigma 18-50/2.8 is known to be very good, but I'm not aware of any other.
I guess that Michael is right that a price tag around 2500 USD would be reasonable for a camera like this.
Four thirds is a different issue, the lenses for 4/3 are made for that format.
Best regards
Erik
The only reason I can surmise for the high price is the fact that there is no other crop-format camera on the market with such 'effectively' high resolution. 30mp for a cropped format DSLR is impressive, hence the impressive price.
The A900 is a heavier camera and lacks the advantages of the cropped format, such as better DoF at the same aperture, and lighter lenses when such lenses are designed for the cropped format, and lighter lenses always in relation to an 'effective' focal length, even with full-format lenses.
The Sigma SD1 is offering a level of performance, in certain respects, that no other camera currently available is able to offer. That's the reason for the high price.
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Hi,
Yes, there are some advantages to cropped format. On the other hand there may not be so many really high quality lenses optimized for APS-C, especially not with Sigma bayonet. The Sigma 18-50/2.8 is known to be very good, but I'm not aware of any other.
I guess that Michael is right that a price tag around 2500 USD would be reasonable for a camera like this.
Four thirds is a different issue, the lenses for 4/3 are made for that format.
Best regards
Erik
Erik,
I think there's a misconception that companies price their products on what's reasonable or fair.
Rather, I suspect that companies price their products on what price they can get away with. Sometime an exceptionally high price indicates 'exclusivity', and therfore appeals to the rich. Sigma with the SD1 have gone down this path. They've got a unique product and they are exploiting that fact.
People who buy designer clothes at three times the price of a regular item which is just as good, will buy the DS1.
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Rather, I suspect that companies price their products on what price they can get away with. Sometime an exceptionally high price indicates 'exclusivity', and therfore appeals to the rich. Sigma with the SD1 have gone down this path. They've got a unique product and they are exploiting that fact.
According to the review, this is what I could gather about Sigma:
1. No support for third-party lenses
2. Only a few good lenses in its stable
3. Not good enough pro support
4. No weatherproofing
5. Very poor software for RAW processing
6. A very subjective color style
7. Poor resale value, because of
8. Poor brand value and image among professionals - you only go for a sigma if you can't afford a Zeiss or Leica, Canon or Nikon.
The only major advantage is its 30MP image. The D3X has 24MP, which is only an inch or so smaller in terms of resolution (when printing) when compared to the SD1, but has features that put every other camera to shame - at almost the same price point. I'm not an expert but I'm not too sure Sigma has a unique product.
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According to the review, this is what I could gather about Sigma:
1. No support for third-party lenses
2. Only a few good lenses in its stable
3. Not good enough pro support
4. No weatherproofing
5. Very poor software for RAW processing
6. A very subjective color style
7. Poor resale value, because of
8. Poor brand value and image among professionals - you only go for a sigma if you can't afford a Zeiss or Leica, Canon or Nikon.
The only major advantage is its 30MP image. The D3X has 24MP, which is only an inch or so smaller in terms of resolution (when printing) when compared to the SD1, but has features that put every other camera to shame - at almost the same price point. I'm not an expert but I'm not too sure Sigma has a unique product.
30mp on a cropped format is significantly different from 24mp on full frame. I've made many comparisons with my Canon cameras comparing full frame with cropped frame at higher pixel count. The Sigma SD1 is definitely unique in terms of resolution for a cropped format camera, assuming it is true that the pixel count on the Foveon is equal to double the pixel count of a Bayer array.
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Hi,
25 MP APS-C is said to be around the corner from Sony (Alpha 77) and Nikon D400, would be an improvement over 16 MP on APS-C in some regards, like better interpolation and less need for AA-filtering. Both cameras may show up in August (this year) according to rumors.
It will be interesting to see some test charts from the SD1, but it may be the case that the SD1 works better on "real subjects" than test charts.
Best regards
Erik
30mp on a cropped format is significantly different from 24mp on full frame. I've made many comparisons with my Canon cameras comparing full frame with cropped frame at higher pixel count. The Sigma SD1 is definitely unique in terms of resolution for a cropped format camera, assuming it is true that the pixel count on the Foveon is equal to double the pixel count of a Bayer array.
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Sigma's desire to go it alone with RAW software processing is absurd. I can remember life before Lightroom and I'm not going back there. If a camera's (RAW) photos cannot be integrated with a work flow that involes using only Lightroom then I'm simply not interested in even thinking about comparing it to other caemras and it may as well not exist.
I can't help but wonder what the decision makers at Sigma were thinking when they decided on (a) the price and (b) not to work with companies like Adobe for the benefit of Lightroom.
Is it really just a demonstration camera that is not actually meant to sell or be used?
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30mp on a cropped format is significantly different from 24mp on full frame. I've made many comparisons with my Canon cameras comparing full frame with cropped frame at higher pixel count. The Sigma SD1 is definitely unique in terms of resolution for a cropped format camera, assuming it is true that the pixel count on the Foveon is equal to double the pixel count of a Bayer array.
So is 30MP on a cropped sensor better than 24MP on full frame? In your comparisons with Canon cameras, did higher resolution APS-C sensors beat lower resolution FF sensors?
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Hi,
I'm a bit familiar with Ray's reasoning. A full frame camera needs to be stopped down more to achieve equivalent depth of field. That is absolutely correct.
My view is that larger sensor size is an advantage. If the sensor pitch is the same a full frame camera will have higher resolution because of having more pixels. This would be the case if we compare the Nikon D300 and the Nikon D3X. The sensor used in the two cameras is pretty closely related. My guesses:
- The Nikon D3X has better resolution than the D300 when neither is cropped.
- If Nikon D3X is cropped to DX size the resolution would be the same
On the other hand, if we compare the D3S or D700 it will probably not resolve significantly better than the D300! The reason is that the pixels are bigger. Theoretically the lens would transmit a higher MTF trough the lens. BUT, there is an optical low pass (OLP) filter that blurs the image slightly so to reduce aliasing close to Nyquist. Larger pixels mean a stronger filter! The aim of the OLP/AA filter is to keep MTF (or microcontrast) down at what is know as the Nyquist limit to around 20-30%.
The result is by and large that regarding sharpness a 12 MP sensor will behave the same, independent of size (within limits). The discussion presumes pretty decent lenses.
A larger sensor will collect more light and will therefore work better at high ISO and have better dynamic range. On the other hand, all full size sensors are around three years old. There is a new generation of sensor from Sony, used in the Nikon D7000, Pentax K5 and the Sony Alpha 580 that has extremely low readout noise and therefore excels in dynamic range.
A knowledgable poster on this forum really indicated that the K5 has better DR than his Phase One P45+! He even posted raw images!
No doubt, new sensor will be coming. Sony and Nikon will probably announce new APS-C cameras based on Sony's latest sensor technology this autumn, maybe in August according to rumors. Rumors say 25 Mpixels, and a brand new sensor.
Will the new 25 MP APS-C sensor beat the old 24.6 MP full frame sensor? Maybe, maybe not! Especially Nikon did a very good job on the D3X, the AA-filter on that camera is weak. No doubt, the new 25 MP APS-C sensor need less AA-filtering.
Finally lenses are most important. Shrinking the pixels take us close to physical limits.
Best regards
Erik
So is 30MP on a cropped sensor better than 24MP on full frame? In your comparisons with Canon cameras, did higher resolution APS-C sensors beat lower resolution FF sensors?
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I can't help but wonder what the decision makers at Sigma were thinking when they decided on (a) the price and (b) not to work with companies like Adobe for the benefit of Lightroom.
why do you think it is Sigma to blame and not Adobe Labs developers having no time to fix their code ? which, by the way, was never updated to reflect the changes that Adobe Labs did w/ ACR v6.x/LR3.x for NR, etc even for the Sigma cameras that were supported ! It is just not on their list of priorities...
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Hi,
Sigma is different as it doesn't have filters and Bayer Matrix. So processing is very much different from what ACR/LR does. Adobe could build a different processing engine for the Foevon, if given enough information by Sigma but the question is if there is enough return on investment?
Best regards
Erik
why do you think it is Sigma to blame and not Adobe Labs developers having no time to fix their code ? which, by the way, was never updated to reflect the changes that Adobe Labs did w/ ACR v6.x/LR3.x for NR, etc even for the Sigma cameras that were supported ! It is just not on their list of priorities...
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Hi,
Sigma is different as it doesn't have filters and Bayer Matrix. So processing is very much different from what ACR/LR does. Adobe could build a different processing engine for the Foevon, if given enough information by Sigma but the question is if there is enough return on investment?
Best regards
Erik
the mere fact that Adobe does support Sigma cameras prior to SD1 says that Adobe has all the information...
also in terms of processing... ACR/R deal w/o issues w/ linear DNGs and Tiffs - and those are not much different from Foveon (once you will do the color transformations to bring the Foveon data into RGB realm) ;D
the simple truth is that nobody there (in Adobe Labs) has time or desire to finally update the code.
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So is 30MP on a cropped sensor better than 24MP on full frame? In your comparisons with Canon cameras, did higher resolution APS-C sensors beat lower resolution FF sensors?
Absolutely! This new Foveon sensor is slightly larger than previous Foveon sensors. It has a crop factor of about 1.5X, ie. a full frame sensor is 2.5x the area.
A full frame 35mm Foveon sensor with the pixel pitch of the SD1 would be the equivalent of a 67.5mp Bayer sensor, so your question is a bit like, "Is a 67mp full frame sensor higher resolution than a 24mp full frame?"
Of course, the result will depend on the use. There will not be much difference between 30mp and 24mp when lenses of different focal lengths are used to maintain equal FoV using the the full area of each sensor. However, when using the Bigma 300-800 with the SD1 at 800mm, which becomes effectively 1200mm, there should be a very noticeable increase in resolution compared with a 24mp full frame cropped to the same FoV. One is then effectively comparing 10mp with 30mp.
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From a linear raw RGB file, all you need is a colour correction matrix so that's relatively simple for Adobe to support linear DNGs and Tiffs. There's a lot of work needed to get a Foveon raw to linear RGB though - you need special processing to extract RGB from the three layer data (which diagrams depict as RGB, but it's not really) and some strong chroma NR to cope with the noise induced by the above processing. If the Foveon did produce good RGB data as is often assumed, indeed there'd be little work for Adobe or anyone else to support it's raws, but producing an RGB image from a Foveon raw needs more processing than it takes to get RGB from a Bayer mosaic colour filter array camera. It's worth reading the Foveon white papers: http://www.foveon.com/article.php?a=74 to understand more about their chip.
http://www.foveon.com/files/CIC13_Hubel_Final.pdf is perhaps the most interesting. Gems include "Using a direct image sensor such as Foveon’s X3 technology, reduces the requirement of a blur filter because aliasing occurs in all color channels equally giving no brightly colored aliasing fringing." - reduces, not eliminates, and the obvious conclusion from this is that without an OLPF aliasing will occur on a Foveon. Obviously Sigma omit this aspect of the camera an allow for luma aliasing which can look like a sharper image, but is really just artifacts. Given their removable dust shield IR filter, I'm surprised that now that they have a good native resolution they don't supply an OLPF/IR combo filter for this position to remove aliasing for photographers where such artifacts would be an issue.
On page two of that paper, under "New Image Processing Methods" we see the comparison of a typical image processing pipeline "A" for a Bayer CFA, with "B" and "C" from a Foveon. "the color correction transformation matrix required to convert the native sensor signals to a standard color space is aggressive compared with conventional camera sensors and this amplifies noise." - the diagrams show the "noise suppression" blocks necessary in the Foveon pipeline, and although they show such a block in "A", from experience I know that such a block is not particularly necessary. They also employ decimation tricks to get more performance out of the slow NR blocks, because as we know, good NR is not fast.
I don't agree with Michael's statement in the review "Some people may not be aware of it, but Color / Chroma Noise and its associated removal tool in various processing programs is there to remove noise introduced by Bayer Filter Array decoding. One would therefore assume that a Foveon type X3 sensor, which doesn't use a Bayer Matrix, wouldn't have Color Noise, and indeed it doesn't." Chroma noise comes from the colour correction matrix amplifying sensor noise. Without such a matrix a Bayer CFA image looks a bit under-saturated, and has some hue errors. As noted, the Foveon has a very aggressive colour correction matrix, and you can see how necessary that is by looking at the paper above with the spectral responses of the three layers and by how much they overlap each other. It's the overlap that needs to be removed by the CC matrix, and the more overlap, the stronger the matrix, and the more noise amplification, hence the necessary NR steps in the Foveon processing mentioned above. In a Bayer CFA, chroma noise does not come from the demosaic process, but instead from the CC matrix, which due to the use of good dye filters on the CFA is a much less noise inducing matrix than that used on Foveon.
I think the colour anomalies noticed by Michael, the red hue in the shadows, the colours not being "right" are fully due to the issues with extracting colour information from the Foveon sensor. As all things are a balance, these colour anomalies and associated NR processing are the price paid for lack of chroma moire. If you don't get chroma moire in your shots (and even if you do, it's usually quite easy to remove), you'll achieve much better colour accuracy from a Bayer CFA.
Graeme
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Perhaps it didn't come across clearly in the review, but we did that. The results were exactly as Michael described. The 645D pulled clearly ahead, to my eye the Leica was in second place, and the A900 and SD1 were very close with the A55 bringing up the rear by a small margin.
- N.
I enjoyed reading the review and found it to be excellent overall. However, one criticism is that Light Room sharpening was used exclusively. As is well known, cameras with low pass filters require more sharpening than those lacking such a filter. Michael did take this into account, but some authorities have reported that deconvolution sharpening is the best method to restore micro-contrast and loss of resolution secondary to the use of a low pass filter.
For example, in his comparison of the Nikon D3X to the Leica S2 Digilloyd (a pay site well worth its modest cost) found that deconvolution sharpening with the Richardson-Lucy (RL) algorithm brought the results obtained with these two cameras nearly to parity and that he was unable to obtain equivalent results for the Nikon with ACR/light room. According to Eric Chan, the latest iterations of ACR do enable deconvolution sharpening, but the number of iterations must be relatively low, since the conversion is much faster than programs using RL.
Bart vanderWolf has also advocated deconvolution sharpening as giving the best results.in my own testing with the Nikon D3and the latest version of ACR, I have been able to obtain micro-contrast and resolution very similar to that obtained with Focus Magic, which is another deconvolution algorithm.however, focus magic requires considerably less fooling around with the settings.
Regards,
Bill
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\but producing an RGB image from a Foveon raw needs more processing than it takes to get RGB from a Bayer mosaic colour filter array camera. It's worth reading the Foveon white papers: http://www.foveon.com/article.php?a=74 to understand more about their chip.
you can just see the dcraw code instead.
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Hi,
The issue is more to interprete color information and handling perception of color than programming.
Best regards
Erik
you can just see the dcraw code instead.
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I'd be curious to see how the Bayer cameras would do against the SD1 with a floating point raw converter, like RPP. The amount of detail one gets out of RPP compared to ACR is pretty stunning.
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For example, in his comparison of the Nikon D3X to the Leica S2 Digilloyd (a pay site well worth its modest cost) found that deconvolution sharpening with the Richardson-Lucy (RL) algorithm brought the results obtained with these two cameras nearly to parity and that he was unable to obtain equivalent results for the Nikon with ACR/light room. According to Eric Chan, the latest iterations of ACR do enable deconvolution sharpening, but the number of iterations must be relatively low, since the conversion is much faster than programs using RL.
Indeed, the D3x files sharpen real well through deconvolution alogs thanks to the weak AA filter of the body, yet have very few digital artifacts in them.
I am still unclear what it would take for Nikon, or any other DSLR manufacturer, to release a body that would deliver enough real world additional value to convince me to spend the cash. The truth of the matter is that the only thing preventing someone using a D3x + stitching to deliver the best landscape images in the world at any print size is... lack of skills.
If I need to spend money on equipment, then the replacement of my old B&W speakers appears to be of higher priority. :)
Cheers,
Bernard
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to deliver the best landscape images in the world
But what about the best skin tones? And what about tornado chasers -- would their shots be best done with stitching? What about motocross racing...this site may have "landscape" in its name, but most people here shoot more than landscapes. So "best" is, at best, a fairly slippery concept.
That said, I still don't see the reason for all the excitement about Foveon, or even why people see so much "potential" in it. What, exactly, would it do better that what we have? What *could* it do better? I think some people like it for the theoretical efficiency of its engineering, rather than for imaging reasons. Does anybody here except Ray (excuse me, Ray) really believe in that 3x multiplier effect, or whatever it is?
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Absolutely! This new Foveon sensor is slightly larger than previous Foveon sensors. It has a crop factor of about 1.5X, ie. a full frame sensor is 2.5x the area.
A full frame 35mm Foveon sensor with the pixel pitch of the SD1 would be the equivalent of a 67.5mp Bayer sensor, so your question is a bit like, "Is a 67mp full frame sensor higher resolution than a 24mp full frame?"
Of course, the result will depend on the use. There will not be much difference between 30mp and 24mp when lenses of different focal lengths are used to maintain equal FoV using the the full area of each sensor. However, when using the Bigma 300-800 with the SD1 at 800mm, which becomes effectively 1200mm, there should be a very noticeable increase in resolution compared with a 24mp full frame cropped to the same FoV. One is then effectively comparing 10mp with 30mp.
Thank you, Ray, for that explanation. Its utility makes a little more sense now, especially in relation to telephoto work.
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I don't agree with Michael's statement in the review "Some people may not be aware of it, but Color / Chroma Noise and its associated removal tool in various processing programs is there to remove noise introduced by Bayer Filter Array decoding. One would therefore assume that a Foveon type X3 sensor, which doesn't use a Bayer Matrix, wouldn't have Color Noise, and indeed it doesn't." Chroma noise comes from the colour correction matrix amplifying sensor noise. Without such a matrix a Bayer CFA image looks a bit under-saturated, and has some hue errors. As noted, the Foveon has a very aggressive colour correction matrix, and you can see how necessary that is by looking at the paper above with the spectral responses of the three layers and by how much they overlap each other. It's the overlap that needs to be removed by the CC matrix, and the more overlap, the stronger the matrix, and the more noise amplification, hence the necessary NR steps in the Foveon processing mentioned above. In a Bayer CFA, chroma noise does not come from the demosaic process, but instead from the CC matrix, which due to the use of good dye filters on the CFA is a much less noise inducing matrix than that used on Foveon.
I think the colour anomalies noticed by Michael, the red hue in the shadows, the colours not being "right" are fully due to the issues with extracting colour information from the Foveon sensor. As all things are a balance, these colour anomalies and associated NR processing are the price paid for lack of chroma moire. If you don't get chroma moire in your shots (and even if you do, it's usually quite easy to remove), you'll achieve much better colour accuracy from a Bayer CFA.
I think that the biggest problem with this "review" was that Mr Reichmann is not competent to write reviews invoving the digital imaging technology. That is not his strength. There were numerous errors and inaccuracies in the article - the one you quoted here is a great one (I had to read it twice to make sure he really said what he said and then I had a good long old fashioned laugh rolling down the floor :D) - yet it was posted.
Here's a quick short list of some problems in the article:
- Foveon is on a sensor with stacked RGB, but instead the top layer gathers pretty much all violet, almost all blue, plenty of green and many red photons as well, the middle one most of the remaining green, plenty of orange and red photons as well, while the bottom tries to capture the remaining photons. Calling this color soup "RGB" is misleading.
- No decent demosaicing algorighm uses mostly green pixels for luminance.
- He mixes pixel count and resolution. Resolution is one dimensional, thus making a statement like "pixel resolution on a Bayer sensor should be reduced (for purposes of comparison) by about a third" is problematic as some read it as the pixel count should be about 2/3 in comparisons, while the word resolution itself indicates that this should be read as 4/9 of the pixel count. Both are of course wrong. The demosaicing itself reduces resolution potential, depending on the algorithm used, by about 10%. And then he repeats the baseless claims that X3 resolution should be double (when comparing to Bayer CFA imagers). Adding these two claims together makes a Foveon pixel worth more than four Bayer CFA pixels for resolution. The reality is of course that the difference is very small and it is the AA-filter which makes most Bayer CFA equipped imagers look less detailed (and to a certain extent be less detailed as well).
- He talks about sharpening, images being optimally sharpened, but the sample crops show that the images from the AA-filtered cameras are clearly undersharpened. I added some sharpening (with no visible sharpening artifacts) and suddenly the A55 image looked easily as sharp and detailed as the SD1 image. Proper capture sharpening is critical for cameras with anti-alias filter.
- His understanding on why the Foveon colors are inaccurate is nonexistent. There are two problems with this sensor and neither he knows of, but instead wonders if the color "palette" is Sigma's choise or software error - the Foveon (technology) has extremely poor color separation and mememerism issues (ie. when two spectra look the same color to human eye, they may look very different to Foveon and vice versa) which are impossible to fix.
- He implies that the sensor is great when he says it deserves great lenses. I imagine the worst colors in the industry, low dynamic range and high noise are not relevant when reviewing a quality of a sensor.
- He praises the smoothness of color transitions and talks about 12 and 14 bits - the sample files are noise reduced, but since they're JPGs, it's hard to say how much is because of the raw-conversion. The noise reduction makes the transitions appear smoother - bits have nothing to do with it as most imagers could do well without the 13th and 14th bit as they're just noise even at the base ISO (yes, including medium format, Pentax and Phase One included).
- His eyes tell him that upto ISO 800 the IQ is "excellent" and then suddently at ISO 1600 marginal - if such a drop happens with one level adjustment, there is something wrong somewhere in the analysis. In this case it is almost certainly the noise reduction used. I imagine the (edge detecting) algorihm Sigma uses doesn't work well on noisy images, thus ISO 1600 is bad. Also to my eyes the fine details started deteriating almost immediately after the base ISO. Too bad the crops he provided are of the worst kind. The only thing the flat surfaces tell is that there is lots of noise reduction being done somewhere as pushing and twisting the images doesn't show even photon shot noise. He doesn't see this, but thinks the sensor is great.
The Leica lens used in the sharpness test seems awesome, easily the best of the bunch. I want one ;)
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Well Aku, you certainly seem to have fun dissing me and my write-up.
The problem is that while your comments certainly sound definitive, each one can be rebutted and even discounted – or at least is the subject for some debate.
Since I have no time or desire to refute your comments on a point-by-point basis, it'll leave it by saying that the article was reviewed prior to publication by several knowledgeable industry commentators, including a couple with extensive Foveon background and experience. There were no substantive errors noted.
Let's just leave it at that.
Michael
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I have to say that I'm giving full authority to MR experience.
This comes to a simple fact: each time (without just one exception) I had the oportunity to work (not only try but work) with equipment he reviewed,
it completly matched with what I was experiencing.
If I had to read reviews in order to help me choose a gear, I'd just have to open this website and could blindly trust the content with confidence.
That's what makes Lu-La's reputation and I think it's well deserved.
The last time I had a doubt on Michael's evaluation was on this Panasonic GH2. I honestly didn't beleived his enthousiasm but finaly purchased one for motion
and after a while with the camera, I have nothing else to admit that his comments where again spot-on.
The trustable Michael's experience comes IMO from 2 direction: a deep knowledge of the image industry and a truth knowledge as a photographer
who's been working with almost all equipment produced on earth. Yes, he may not be an engineer but I couldn't care less because each time
testings are done following a rigourous "scientific" pattern, they simply don't match (or rarely match) with the field results while the field evaluations
of mister Reichmann yes do match. In this sense I find his writings a trustable source of information, much more reliable than most of the testing websites
with the exception of a few, that come to the same conclusions anyway.
We shouldn't forget that MR is in touch regularly with techs and engineers within the profession, used to run an art gallery, is a master of prints, used to
worked in the industry as a profesional (most of the people who present themselves under the scientis label and think they know have never worked as a professional,
neither photographers nor engineers in this industry. The exception here is Graeme and maybe a few more we could count on the finger's hand), and has been using more gear of all kind that I would probably never see in my entire life.
He is in the confidence of some manufacturers and knows things we don't.
So yes, personaly, I give him all the credits he deserves when it comes to gear and image (quality) knowledge.
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Interesting thing is, when I first started interacting with sensor designers, one of the first questions I asked is about the Foveon design. I wanted to know why it looked as it did, and why such a technique was not more wildly used. The simple answer is that silicon depth is a very poor colour filter. You can see that from the published Foveon response curves that I referenced above. Almost everything about the image stems from this fundamental element of the design of how it senses colour, and the necessary math needed to untangle a proper colour response from the heavily over-lapping curves.
Graeme
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One thing I noticed is that when attempting to equate pixel counts between the two technologies (in the P645 section), Michael appears to write that you have to account for both the demosaicing losses and the x2 factor often attributed to Foveon. Is this not double counting? If you call the Foveon sensor 30MP you have already adjusted for demosaicing losses. I can't see any way in which the Foveon sensor is equivalent to 40MP as the article implies!
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On resolution: So let's look at the Foveon SD1 RAW at 4704 x 3136, and for now, linear luma resolution to keep things simple. For a Bayer CFA to achieve a measured horizontal resolution of 4704, and assuming it uses a properly configured OLPF, it would need to have a sensor with 6030 photosites across (assume a 78% photosite to measured resolution factor which is not unreasonable).
Moving that back to MP, that equates to about a 24MP Bayer CFA sensor. Although such a sensor may be susceptible to mild chroma moire, it will be much less prone to luma aliasing than the un-filtered Foveon.
Of course, if we properly filter the Foveon so that it has similarly low levels of luma aliasing as the above 24MP Bayer CFA, it probably measures around 4000 x 2666 in terms of measured resolution (very OLPF dependent and hard to guess...) To get a similar measured resolution with similarly low luma aliasing we'd need 5128x3418 on Bayer CFA, around 18MP.
So what it comes down to is weighing up the factors....
1) does Chroma moire bother you in your shots, and if it appears, is it hard to remove?
2) does luma moire bother you in your shots. Luma moire is particularly difficult to deal with (unlike chroma moire which is relatively easy in most cases)
3) is colour accuracy important
4) is noise important, or in other words, how important is dynamic range to you, or looking another way, high ISO performance, as all these factors are inter-linked.
If lack of Chroma moire is the most important factor to you, then a Foveon sensor makes some kind of sense. If luma moire is important to you, go Bayer CFA with an OLPF. If such moire doesn't bother you, try a Bayer CFA without OLPF and see how you get on. If colour or noise are important, go Bayer CFA.
Graeme
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I think that the biggest problem with this "review" was that Mr Reichmann is not competent to write reviews invoving the digital imaging technology. That is not his strength. There were numerous errors and inaccuracies in the article - the one you quoted here is a great one (I had to read it twice to make sure he really said what he said and then I had a good long old fashioned laugh rolling down the floor :D) - yet it was posted.
It is difficult to assess the reliability of statements made by a newbie with only 5 previous posts and with no CV (curriculum vitae) listing his qualifications or prior publications. I would suggest that Michael is eminently qualified to make a subjective review of the camera. He is a very experienced photographer and has worked with all types of cameras and has extensive contacts in the photo industry whose advice he can seek. His observations are likely valid, but his technical explanations for what he sees may or may not be accurate. I will leave that to the experts with advanced degrees and experience in digital imaging.
DXO is going to evaluate this camera some time in July and we will have some technical data with which to work and they may add their own comments. For example, their comparison of the Nikon D5000 and the Canon EOS 500D demonstrates how relatively high "color blindness" requiring large matrix coefficients can degrade image quality. Does this apply to the Sigma?
Regards,
Bill
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It will be interesting to see some test charts from the SD1, but it may be the case that the SD1 works better on "real subjects" than test charts.
Hi Erik,
A good, and meaningful, test(card) shot is as telling as "real subjects". But then there would no longer be discussions about mythical properties attributed to an overpriced camera/sensor ...
Cheers,
Bart
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Test cards are "real world" subjects, just rather boring subjects. The whole idea of test charts is to provide a repeatable scene to a camera so that we can ensure what we see is a result of the camera, not an unintended change in scene.
Aspects like dynamic range are notoriously hard to judge from a typical scene and oh-so-much more accurate with a good chart, for instance. Resolution is also a factor that is not easy to measure on a typical scene, but a well designed test chart can really help on. If you're concerned about aliasing and moire (which I think you should be) you need to know how susceptible your camera system is to such artifacts and how they effect the image and what can be done about it - and you need to know this before you go out and shoot your scene, not after when you're looking at the image in Photoshop and see the issues. For colorimetry, you need to know what colours are an issue, and how different light sources interact with your camera system. The spectral responses of different light sources will behave differently with camera systems, and good charts with measured light sources can really help you know in advance what will work best, and where problems may lie.
Charts are certainly important in camera development, but I think a good photographer needs to understand their camera via charts in such a way that they can maximize performance in the field, and minimize the chance of an anomalous or sub-standard result occurring.
Measurements don't tell you all you need to know about image quality, but what they do tell you is very useful and usually correlates very well with subjective opinion.
Graeme
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Hi bart,
I expect that the resolution test in DPReview will show contrast inversion, but I'm not sure that it would be visible in common subjects.
Otherwise I agree with your view.
Best regards
Erik
Hi Erik,
A good, and meaningful, test(card) shot is as telling as "real subjects". But then there would no longer be discussions about mythical properties attributed to an overpriced camera/sensor ...
Cheers,
Bart
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Luma aliasing shows up on a variety of common subjects - clothing detail and distant brickwork being typical examples. If you're just shooting trees and landscapes it's not so much of an issue, although I and others find it adds an un-natural "crunchiness" to the edges of most in-focus objects and fine detail - your opinion might be that you like that.
Graeme
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Resolution is also a factor that is not easy to measure on a typical scene, but a well designed test chart can really help on.
Test charts have some desirable properties such as controlled settings and repeatability, as you mention. However, it is a fair question to guage the "resolution" of real images or that of typical scenes, which opens up a whole new world of statistics compared to traditionally used methods on test charts. Please see the following link and the messages in that thread to guage the utility of such methods that work on real scenes:
http://forums.dpreview.com/forums/read.asp?forum=1018&message=38170122
Joofa
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It is difficult to assess the reliability of statements made by a newbie with only 5 previous posts and with no CV (curriculum vitae) listing his qualifications or prior publications.
Well, at least we have a picture of Aku Ankka here (http://www.valley.fi/Eng/..%5Cimages/pollee_aku.jpg), and he seems rather authoritative to me.
"Aku Ankka" is the Finnish translation of "Donald Duck." No, I'm not making this up.
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One thing I noticed is that when attempting to equate pixel counts between the two technologies (in the P645 section), Michael appears to write that you have to account for both the demosaicing losses and the x2 factor often attributed to Foveon. Is this not double counting? If you call the Foveon sensor 30MP you have already adjusted for demosaicing losses. I can't see any way in which the Foveon sensor is equivalent to 40MP as the article implies!
Huh? I never wrote that the SD1 was equivalent to 40MP. Please reread what I did write.
It's not double counting to reduce one and increase the other, for the reasons given, if the point is to try and find an equivalence.
Michael
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I'd be curious to see how the Bayer cameras would do against the SD1 with a floating point raw converter, like RPP. The amount of detail one gets out of RPP compared to ACR is pretty stunning.
does "stunning" have any numbers or it is another "6 stops of DR" ?
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Resolution is also a factor that is not easy to measure on a typical scene, but a well designed test chart can really help on.
I am an engineer who loves measuring things, but I'll play some devil's advocate here.
I think your conflating "test chart" and "consistency" inadvertently. Yes, consistent scenes are vital for comparisons. That doesn't mean that a test chart that produces numerical metrics is necessarily very useful. Rarely are the arbitrary numerical metrics derived of much use. DxOMark is a classic example. The full SNR curves they produce are actually pretty useful for comparing sensors. Their scores, and even their DR and SNR curves much less so, often to the point of being misleading. A consistently shot studio scene with real objects in a high contrast setting is far more useful to a photographer when it comes to comparing cameras.
I cherry picked the quote above as a classic example. Most resolution tests are completely senseless as they test a portion of the MTF curve that is least relevant to actual photography and ignore the lower frequency portions of the MTF curve that play a much larger role in image formation. Hence the loads of lens "tests" that rate superzooms with very high resolution scores when in fact in practice a real world image at a real world print size from the superzoom will appear far less detailed than a prime with similar "resolution" but a much more robust low frequency MTF.
Test charts, with the right context, can be useful to an engineer as validation. For a photographer they tend to be confusing at best and misleading at worst. Shoot consistent real world scenes, not test charts, if your audience is photographers.
Again, playing devil's advocate here, agree with most of what you say.
Ken
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Ken, I don't really disagree with you too much. If you've got the location to set up a permanent test scene, I think that's a superb "test chart" that can offer valuable data, and present it in a form that's very understandable and comparable across cameras. Most of us don't have that luxury, but a measured light source and some charts is pretty much as good as we can get.
As for resolution, there are indeed people who will ascribe a single figure to resolution and indeed, that's practically meaningless. It's still worse when that figure calculates out to a greater resolution than there are photosites on the sensor! Giving a full MTF plot is indeed useful, and yes, looking at what the low frequencies are doing is very important, especially with lenses.
For resolution though, it's hard to get real-world scenes that allow for ease of measurement and clearly show aliasing. I think when we look at a camera in a critical way, it's very important to actually go out and shoot with the camera system, taking the image all the way through post production. However, good charts are invaluable tools, when well used, to quantify what you're seeing. Indeed, good charts can still be confusing, but then it's our job to educate.
Graeme
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Just a personal view, but there is nothing more uninteresting (to me, as a photograher) than another debate about Bayer / Foveon resolution equivalence etc. The only thing that matters to me is what the files look like on screen or in print. I like the look of Foveon files a lot (maybe I'm that crunchy brickwork guy!) but not enough to sink silly money in to a camera probably worth $2k or so at most. I'd love to see what a 40mp or more Foveon sensor could do in a decent MF body, but I guess I will be even older and wrinklier than I am now before I find out (if I ever do).
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Quentin, I appreciate such a debate can be rather boring :-) I wish it wasn't the topic of conversation as I think with Foveon that there are more important issues like the colorimetry to discuss. However I do think it was good of Michael to get some Bayer CFA cameras that don't use an OLPF because (in terms of luma resolution) it's the OLPF (or lack of it) that people are seeing on Foveon cameras, not an inherent Foveon v CFA advantage in resolution. Yes, there is a luma resolution advantage to not having to demosaic, but it's not as great a detriment to the resolution as the OLPF is. I think we all wish we didn't need an OLPF - they're expensive to make, and the reduce good resolution as well as bad, but as long as we're not using really crap lenses or are running right into diffraction limits at usable apertures, aliasing will be a problem and I think the majority of camera manufacturers agree that it's better to have a lower amount of aliasing artifacts than to have absolutely maximal resolution. Especially for me, the dangers of aliasing are a lot worse with motion than for stills. With a still you can "fix" a single frame, but for motion, it gets expensive, and motion shows up aliasing much more clearly than stills as the aliases move in the opposite direction to the motion of the objects that are aliasing. On the chroma side, as pointed out above, you're trading inherent lack of chroma moire for necessarily strong chroma NR and poor colour accuracy. I think photographers need to know what the tradeoff is there, and what it means to them and their photographs.
The real aspect not really addressed in the review, and one that is, or at least should be, of great interest to photographers, is dynamic range, and that's an area where the Foveon could have issues. I'd be very keen to see how it performs there.
Michael did a great job discussing the workflow and ergonomic issues, and those are the aspects we can't measure on charts - they need a competent human.
Graeme
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Graeme,
I avoided the black hole of dynamic range, simply because without a Stauffer Wedge or similar it's almost impossible to measure, and visual judgement of this parameter is notoriously unreliable.
Michael
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A black hole it is indeed!
Graeme
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I thought it had been fairly well established over the years that each Foveon pixel, consisting of 3 stacked sensels, is approximately equivalent to two Bayer type sensels, or slightly less, in terms of apparent resolved detail and sharpness.
However, until more extensive comparisons are made with this new model, we won't know for certain. It could be the case, as the pixel count of the Bayer type sensors has increased (and will contunue to increase) and their AA filters have become increasingly weaker, the resolution advantage of that lack of an AA filter in front of the Foveon sensor is accordingly reduced slightly.
The issue of pricing is interesting. Whilst I sympathise with the frequently expressed outrage at the high price of the SD1 compared to other models of cameras that appear to offer more features, I see lots of products on the market that are outrageously priced in my view, and I therefore don't buy them.
It could be the case that Sigma are not particularly worried if you don't buy the SD1 because their manufacturing is currently geared for only a small output. Maybe the recent earthquake and tsunami in Japan has affected this pricing decision.
Let's suppose, for example, that Sigma is able to produce only 500 units a month, as a result of disruptions in Japan.
Ask yourselves which is better from Sigma's point of view, to sell 500 units a month at $2,000 each, resulting in a shortage of supply, long back-orders and angry customers, or to sell 300 units a month at $7,000 each, resulting in plenty of stock in all the retail outlets and warehouses, and a gradual accummulation of unsold stock which can be later sold at a substantial discount.
I notice from rereading Michael's article, that the SD1 has another unique feature, apart from its being the highest resolving cropped format camera on the market. It has a user-removable IR filter allowing the camera to be used for infrared photography.
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Hi,
I may agree on resolution figures being less than relevant, but I have not seen any example of a really well corrected lens that did not have high resolution.
I'd say that much of the contradiction regarding resolution and contrast is coming from the fourties, before antireflex coatings were perfected. A lens which corrected most aberrations well had many surfaces and therefore a lot of flare. We are now in much better control of flare but the perception of contradiction of "resolution" and contrast are still with us.
A well constructed lens today has both high MTF at all frequencies and high resolution.
Best regards
Erik
Ken, I don't really disagree with you too much. If you've got the location to set up a permanent test scene, I think that's a superb "test chart" that can offer valuable data, and present it in a form that's very understandable and comparable across cameras. Most of us don't have that luxury, but a measured light source and some charts is pretty much as good as we can get.
As for resolution, there are indeed people who will ascribe a single figure to resolution and indeed, that's practically meaningless. It's still worse when that figure calculates out to a greater resolution than there are photosites on the sensor! Giving a full MTF plot is indeed useful, and yes, looking at what the low frequencies are doing is very important, especially with lenses.
For resolution though, it's hard to get real-world scenes that allow for ease of measurement and clearly show aliasing. I think when we look at a camera in a critical way, it's very important to actually go out and shoot with the camera system, taking the image all the way through post production. However, good charts are invaluable tools, when well used, to quantify what you're seeing. Indeed, good charts can still be confusing, but then it's our job to educate.
Graeme
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Michael
I can only try and interpret what you wrote here:
"If we assume (and I did going into this test) that a Foveon sensor actually has comparatively about double its linear resolution (so about 30MP for the SD1) and a Bayer equipped camera such as the 645D has about 1/3rd less effective resolution than its actual pixel count (again about 30MP for the 645D), this could actually be a competitive IQ horse race."
The Sd1 has an actual 15MP sensor, the 645 a 40MP sensor. We know that Foveon and Bayer MP are not worth the same, and to come to an agree equivalence, we can make some assumptions (as you do). We can either:
- assume the Foveon is worth more than is nominal 15MP (say 2x or 30MP)
or
- assume Bayer is worth less than its nominal pixel count (say 2/3 or 30MP)
If we do the first, we are describing 30MP equivalence vs 40MP. If we do the second, we are describing 15MP vs 30MP equivalence.
The two methods don't arrive at 30MP equivalence for both and certainly shouldn't both be employed to come to a figure that suggests that the two cameras are competitive!
What you should do is say that demosacing loses about 30% of resolution and AA filtering (for those who have it) about another 20% so a camera like the A900 is only resolving something equivalent to about a 12mp Foveon. The 645 without an AA filter probably resolves about the same as a 30MP Foveon would. The SD1 with 15MP Foveon pixels has only half the effective pixel count of the 645. Hardly a "competitive IQ horse race"....
Huh? I never wrote that the SD1 was equivalent to 40MP. Please reread what I did write.
It's not double counting to reduce one and increase the other, for the reasons given, if the point is to try and find an equivalence.
Michael
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I thought it had been fairly well established over the years that each Foveon pixel, consisting of 3 stacked sensels, is approximately equivalent to two Bayer type sensels, or slightly less, in terms of apparent resolved detail and sharpness.
Hi Ray,
NO!!! What has been established is that for Luminance most of the difference is not due to the Bayer CFA, but to the Optival Low Pass Filter (OLPF). It's the strength of the OLPF that determines the difference for the most part, with only some 7% attributable to the Bayer CFA. Where the Foveon shines in comparison is in Chroma resolution, which for human vision is less important (unless you shoot a lot of Red on Blue subjects with nearly identical Luminance). A test chart designed specifically for that purpose can be used to determine a worst case scenario. Comparing the MTF curves for the worst case and best case scenario can be quite informative.
Real life images will have a mix of Chroma resolutions on a Bayer CFA sensor array depending on the difference in the Luminance component of the color under investigation. How Raw converters favor Luminance demosaicking versus Chroma demosaicing will also make a difference, and then there is deconvolution sharpening ..., which works very well on OLPF images.
However, until more extensive comparisons are made with this new model, we won't know for certain. It could be the case, as the pixel count of the Bayer type sensors has increased (and will contunue to increase) and their AA filters have become increasingly weaker, the resolution advantage of that lack of an AA filter in front of the Foveon sensor is accordingly reduced slightly.
Bingo! In addition, most non-Foveon sensor designs have traditionally offered (both physically and in output pixel count) larger sensel arrays than the Foveon.
The only real benefit of a Foveon image is that it responds well to upsampling, where it may hold the apparent resolution a bit better because of the extra Chroma resolution and the lack of an OLPF. In return you get a higher probability of aliasing artifacts, and a much larger Raw file than with an OLPF filtered Bayer CFA Raw of the same output pixel size, and a problematic color accuracy and noise performance.
Cheers,
Bart
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Hi,
Life is not just about pixels. Also, discussing the worth of pixels is not very meaningful. With more pixels you get less interpolation artifacts, like staircase effect on edges. Larger pixels will carry more MTF than smaller pixels, as MTF is higher at lower frequencies. Graeme Netress has made some calculations on this list I think, there is an advantage to the Foveon design, but less than believed.
I got the impression that Michael and Mark (?) has found the Pentax clearly superior and the Leica best of the DSLR bunch, with Sigma being better than the Alpha 900, that being quite a treat from an APS-C camera. The authors judgement is based on large prints.
One thing to point out is that those most knowledgeable about raw-conversion are least optimistic about the Foveon. It has several weak areas. Color sensivity (bad separation of color), low ISO and presumably aliasing effects. Graeme is working with raw-conversion on the RED (high end video cameras). Bart and Bill certainly know what they write about.
Unfortunately, I have seen very few testchart shots with Foevon. Would DP-review test the SD1 we would now more about how it handles aliasing, it is very visible on their test targets, at least with the Sigma DP2.
Best regards
Erik
Michael
I can only try and interpret what you wrote here:
"If we assume (and I did going into this test) that a Foveon sensor actually has comparatively about double its linear resolution (so about 30MP for the SD1) and a Bayer equipped camera such as the 645D has about 1/3rd less effective resolution than its actual pixel count (again about 30MP for the 645D), this could actually be a competitive IQ horse race."
The Sd1 has an actual 15MP sensor, the 645 a 40MP sensor. We know that Foveon and Bayer MP are not worth the same, and to come to an agree equivalence, we can make some assumptions (as you do). We can either:
- assume the Foveon is worth more than is nominal 15MP (say 2x or 30MP)
or
- assume Bayer is worth less than its nominal pixel count (say 2/3 or 30MP)
If we do the first, we are describing 30MP equivalence vs 40MP. If we do the second, we are describing 15MP vs 30MP equivalence.
The two methods don't arrive at 30MP equivalence for both and certainly shouldn't both be employed to come to a figure that suggests that the two cameras are competitive!
What you should do is say that demosacing loses about 30% of resolution and AA filtering (for those who have it) about another 20% so a camera like the A900 is only resolving something equivalent to about a 12mp Foveon. The 645 without an AA filter probably resolves about the same as a 30MP Foveon would. The SD1 with 15MP Foveon pixels has only half the effective pixel count of the 645. Hardly a "competitive IQ horse race"....
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It is difficult to assess the reliability of statements made by a newbie with only 5 previous posts and with no CV (curriculum vitae) listing his qualifications or prior publications. I would suggest that Michael is eminently qualified to make a subjective review of the camera. He is a very experienced photographer and has worked with all types of cameras and has extensive contacts in the photo industry whose advice he can seek. His observations are likely valid, but his technical explanations for what he sees may or may not be accurate. I will leave that to the experts with advanced degrees and experience in digital imaging.
DXO is going to evaluate this camera some time in July and we will have some technical data with which to work and they may add their own comments. For example, their comparison of the Nikon D5000 and the Canon EOS 500D demonstrates how relatively high "color blindness" requiring large matrix coefficients can degrade image quality. Does this apply to the Sigma?
Where did you learn that SD1 is gong to get the DxOMark treatment? I couldn't find such information on their site, but didn't really dig deep ;) If true, it sounds interesting.
Anyhow, when it comes to the "color blindness" you referrerd, the Foveon chip is in totally different world compared to any of it's competition. This is because of the very poor color separation achieved by relying on the probabilistic wavelength dependent penetration depth of photons in silicon, instead of using for purpouse designed organic pigement or dye color filters. In addition, due to the high read noise of the 3T photodiode design (because of no correlated double sampling) and surprisingly low QE especially for the reds due to excess metal in the sensor blocking light (that's 9 transistors per photosite) cripples the colors in low-signal situations (shadows or low light in general) even more. There is an interesting paper on a new Foveon sensor design in the net describing a 4T variant which would be a large improvement (due to CDS) with 4 pixels on the top layer for each pixel on the middle and bottom, but nothing indicates that SD1 has this kind of sensor.
Wikipedia has this image http://upload.wikimedia.org/wikipedia/en/a/ab/Absorption-X3.png (the one on the right was in this article, but the one in the left is actually far more informative) - it's a bit rough, but good enough for the purpouse of realizing that color is an issue with Foveon.
As I don't have a CV as you kindly pointed out, you might want to search DPReview's forums for Joseph Wisniewski's posts on Foveon sensor - he has actually made camera(s) with Foveon sensors and is of known quality (http://www.dpreview.com/members/5851432553).
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Well, at least we have a picture of Aku Ankka here (http://www.valley.fi/Eng/..%5Cimages/pollee_aku.jpg), and he seems rather authoritative to me.
:)
You must be a paparazzi as that's a nice shot of me (or a lookalike).
Actually, Aku and Ankka are very normal names for Finns, just like Kalle and Anka are for Swedes and Paul and Anka are for Entertainers.
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The real aspect not really addressed in the review, and one that is, or at least should be, of great interest to photographers, is dynamic range, and that's an area where the Foveon could have issues. I'd be very keen to see how it performs there.
Michael did a great job discussing the workflow and ergonomic issues, and those are the aspects we can't measure on charts - they need a competent human.
I totally agree that the review (and reviews on this site in general) had a very good workflow-ergonomics etc. part. It's just the technology part that is lacking.
Ayhow, regarding the dynamic range, it is quite modest. The main reason for this is the high noise levels, both read noise and noise from color matrixing. Even if one were to only shoot at the base ISO, the high ISO images tend to tell an interesting story, as if they are noisy relative to the competition, there is no reason for the low ISO images to not be (relative to the competition). High ISO does not increase read noise, instead it may actually lower it compared to the low ISO if the AD converter(s) are noisy (most if not all Canons for example).
The other reason is the tendency of blowing all the channels at once which is due the sensor design. With regular sensors more highlight data can be rescued as the channels tend to blow one at a time.
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I avoided the black hole of dynamic range, simply because without a Stauffer Wedge or similar it's almost impossible to measure, and visual judgement of this parameter is notoriously unreliable.
If you mean measuring DR in general and not just this particular camera, then you are wrong. In general dynamic range is quite easy to measure and calculate. I've done it to my camera, you can do it to yours. Emil Martinec provides moderately straightforward :) instructions on his website http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p2.html (http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p2.html) - you may also be interested in reading http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html (http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html) as well.
I do not know however for a fact, how this particular camera treats it's raw files and/or if it is possible to get data out of the raw-converter without any noise reduction being applied. I do suspect however that it may be impossible to get files out without NR and this would pose a problem.
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I thought it had been fairly well established over the years that each Foveon pixel, consisting of 3 stacked sensels, is approximately equivalent to two Bayer type sensels, or slightly less, in terms of apparent resolved detail and sharpness.
Nope. This is a myth which is advocated by Sigma marketing and Sigma fans (especially in the DPR forum). Actual measurements do not support this claim, nor theory. Bart van der Wolf has an interesting web page (http://bvdwolf.home.xs4all.nl/main/foto/bayer/bayer_cfa.htm)on demosaicing.
Also, as pointed earlier in this thread by someone, the anti-alias filter is the prime culprit for reduced resolution and especially perceived sharpness and is the reason why the images should always be treated with capture sharpening.
Below are three sample images from Pentax K20D, a camera with Bayer CFA and a anti-alias fiter - one is with no sharpening at all, the second is with capture sharpening in Lightroom, and I just threw the third in there as I toyed a bit with deconvolution as it can be used to try to recreate the information smudged by the AA-filter (though for best results a good estimate of the point spread function would be needed).
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Hi,
A Stouffer Wedge is just about 20 box, so it is no exquisite piece of equipment. On the other hand I'd suggest that you can let DxO do their stuff, my understanding is that they are really good at it.
Dynamic range has been somewhat infected, because it seems that different people associate the term with different interpretations. My guess is that DxO figures are absolutely reliable measuring what they do measure.
There is always an issue with measurements, they may give results that contradict other observations.
Example: I tried to match two LCD screens (an Apple iMac and an Eizo Sx). According to my eyes the iMac was much brighter but accoding to my Minolta Spot Meter F they were within 0.1 stop. Than I measured with my old, analogue, Autometer II and got results corresponding to visual impression. The Minolta Spotmeter F is intended for flash and probly measures maximum intensity. The panel probably is puls width modulated, blinks rapidly and intensity is adjusted by varying the length of the blinks. So Spotmeter F picked up peak intensity and Autometer II mean intensity. Lessor learned!
Best regards
Erik
Graeme,
I avoided the black hole of dynamic range, simply because without a Stauffer Wedge or similar it's almost impossible to measure, and visual judgement of this parameter is notoriously unreliable.
Michael
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Hi Erik
I'm not making any conclusions about the technologies here. I'm just pointing out what I interpret as a bit of muddle in the review. It looks to my like Michael has worked out the two alternate ways of identifying rough pixel count equivalence and applied them both (rather than one or the other). This implies that the SD1 resolution might be closer to the 645 than is in fact the case. Obviously, he debunks this later in the review so it doesn't matter than much but I felt it worth pointing out. I've spend much frustrating time over in DPReview engaging in such debates in the past.
By the way I'm a Sd14, SD9, DP1 owner as well a 5D, 450D user, so I've lots of practical experience with comparing relative performance of these cameras!
Hi,
Life is not just about pixels. Also, discussing the worth of pixels is not very meaningful. With more pixels you get less interpolation artifacts, like staircase effect on edges. Larger pixels will carry more MTF than smaller pixels, as MTF is higher at lower frequencies. Graeme Netress has made some calculations on this list I think, there is an advantage to the Foveon design, but less than believed.
I got the impression that Michael and Mark (?) has found the Pentax clearly superior and the Leica best of the DSLR bunch, with Sigma being better than the Alpha 900, that being quite a treat from an APS-C camera. The authors judgement is based on large prints.
One thing to point out is that those most knowledgeable about raw-conversion are least optimistic about the Foveon. It has several weak areas. Color sensivity (bad separation of color), low ISO and presumably aliasing effects. Graeme is working with raw-conversion on the RED (high end video cameras). Bart and Bill certainly know what they write about.
Unfortunately, I have seen very few testchart shots with Foevon. Would DP-review test the SD1 we would now more about how it handles aliasing, it is very visible on their test targets, at least with the Sigma DP2.
Best regards
Erik
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I accidentally shot my SD14 at ISO400 the other day in full sunlight. It was quite noisy even in bright conditions. And the noise was of a different type than you normally see. Instead of the familiar fine grained red and green speckles, there was a kind of filiamentary look at quite a large scale. I would call them blotches rather than speckles but even that isn't quite right. It look a bit like the large scale maps of the universe you see, showing the distribution of matter in the visible universe. Very uneven, with denser areas of noise then voids with no noise. Very different from Bayer noise patterns.
I totally agree that the review (and reviews on this site in general) had a very good workflow-ergonomics etc. part. It's just the technology part that is lacking.
Ayhow, regarding the dynamic range, it is quite modest. The main reason for this is the high noise levels, both read noise and noise from color matrixing. Even if one were to only shoot at the base ISO, the high ISO images tend to tell an interesting story, as if they are noisy relative to the competition, there is no reason for the low ISO images to not be (relative to the competition). High ISO does not increase read noise, instead it may actually lower it compared to the low ISO if the AD converter(s) are noisy (most if not all Canons for example).
The other reason is the tendency of blowing all the channels at once which is due the sensor design. With regular sensors more highlight data can be rescued as the channels tend to blow one at a time.
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So this is actually why I gave up on the forum here. All the undeconvoluted technobabble one cares to read, no matter how scientifically correct, means sweet fuck-all to a photographer. ???
Don't get me wrong, it's ncie to have some bona fide technical experts in the house, especially when they can offer solutions to real-world problems, which they often can, but the only thing that matters is: "what can I get out of this thing?" The camera is only worth what a reasonably skilled and experienced practitioner is able to make it do.
For the easons we both said in the article, the SD1 can produce a fine image. Not quite as good as the Leica (sorry Sean, you have to sharpen images ;)), at demanding applications not all that close to the 645D, and for most everything else just about one par with the A900.
The camera makes nice pictures. They look very sharp. The colours are seriously inaccurate. The camera is of average build and design. There is no magic.
To me, the most telling thing is how little chatter there has been about the reviews of the SD1. The mass of photographer simply don't care. That's very bad news for Sigma, and largely result of the inane pricing.
It could be the case that Sigma are not particularly worried if you don't buy the SD1 because their manufacturing is currently geared for only a small output. Maybe the recent earthquake and tsunami in Japan has affected this pricing decision.
Let's suppose, for example, that Sigma is able to produce only 500 units a month, as a result of disruptions in Japan.
Ask yourselves which is better from Sigma's point of view, to sell 500 units a month at $2,000 each, resulting in a shortage of supply, long back-orders and angry customers, or to sell 300 units a month at $7,000 each, resulting in plenty of stock in all the retail outlets and warehouses, and a gradual accummulation of unsold stock which can be later sold at a substantial discount.
Nope. The economics of sensor wafer fabrication are such that th viable price depends on a good yield, which can really on be achieved after some significant production. Moreover, who is going to tool-up on a specifialized build like this for a few hundred sensors? No one, unless they are charging a fortune for the chip. I am confident that this is not the business model.
Moreover, I had to chuckle a little. While there is, indeed, a customer for everything, I seriously doubt that at this price Sigma will sell more than 300 units worldwide EVER. Not monthly, but throughout history. In 50 years, this will be one hot item at the Westlicht Auctions :-)
- N.
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"means sweet fuck-all to a photographer." - well the meaning of the words might not mean much, but the talk about the visual impact of sensor design decisions directly effects exactly how the photographs you make look.
The layered photosite design of the Foveon, where it uses silicon depth as a colour filter directly impacts the colour accuracy and noise of the image, and it's dynamic range and high ISO performance and imperviousness to chroma moire. It's lack of OLPF directly impacts the perception of fine detail, and luma aliasing performance. I'd say all those parameters mean a lot to the image, and hence to the photographer taking that image. If you don't understand the pros and cons of a camera design, how can you begin to go about getting the best out of the camera for any given situation?
It's just like Michaels discussion of the ergonomics and workflow - they directly impact how the camera is used to take photos, and how the final image is made from what the camera captured. They might not be geeky math issues, but they're technical (rather than artistic) issues that directly impact upon the image.
One of the nicest, to me, things about photography is it is a hobby that combines the technical and the artistic. By understanding the technical you can work around artistic issues, or utilize a camera in such a way as to enable creative possibilities. Similarly, a good creative decision can render certain technical aspects irrelevant to the final image.
So if the geekyness of the why are the colours "seriously inaccurate" that's fine, but the take-away point from the discussion is that it's inherent to the sensor design choices, and not something that's going to get better with a better profile. Again, it's say that's rather important to know.
So indeed, "babble" can mean little to a photograph, but that doesn't mean such a discussion can not be enlightening as to the whys and wherefores of how an image looks the way it does, and what can, and cannot be done to avoid real imaging issues.
Graeme
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To me, the most telling thing is how little chatter there has been about the reviews of the SD1. The mass of photographer simply don't care. That's very bad news for Sigma, and largely result of the inane pricing.
- N.
I think all of us read the review and found it quite informative. Some of us are scientists and are interested in the physics behind the sensor and what is required for the processing pathway in order to get good images. I wouldn't be so harsh on us techno-geeks. I posted early on about the shocking price for this camera, even before the review was posted. Of course the proof is really in the images and whether they are better/worse than competitive products. I've found the tech discussion extremely interesting as I was not familiar with the Foveon sensor before and it has sparked my interest to read a lot more about it. Whether Sigma will continue to work on this sensor or not will largely be a marketplace response. At this pricing point it does not look promising.
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:)
You must be a paparazzi as that's a nice shot of me (or a lookalike).
Actually, Aku and Ankka are very normal names for Finns, just like Kalle and Anka are for Swedes and Paul and Anka are for Entertainers.
I bet you even live in Ankkalinna (Duckburg)...
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So this is actually why I gave up on the forum here. All the undeconvoluted technobabble one cares to read, no matter how scientifically correct, means sweet fuck-all to a photographer. ???
Don't get me wrong, it's ncie to have some bona fide technical experts in the house, especially when they can offer solutions to real-world problems, which they often can, but the only thing that matters is: "what can I get out of this thing?" The camera is only worth what a reasonably skilled and experienced practitioner is able to make it do.
For the easons we both said in the article, the SD1 can produce a fine image. Not quite as good as the Leica (sorry Sean, you have to sharpen images ;)), at demanding applications not all that close to the 645D, and for most everything else just about one par with the A900.
The camera makes nice pictures. They look very sharp. The colours are seriously inaccurate. The camera is of average build and design. There is no magic.
I think all of us read the review and found it quite informative. Some of us are scientists and are interested in the physics behind the sensor and what is required for the processing pathway in order to get good images. I wouldn't be so harsh on us techno-geeks.
One reason there's so much talk of tests and technology is because they're easy to talk about, if you want to take the time to learn the language and the math. Most things are defined. Unfortunately, much of the stuff that Michael talks about in his review *isn't* easy to talk about, because sometimes it seems we don't even have a proper language for it, much less any agreed-upon definitions. Again, unfortunately, that's the stuff that's most important to some of us -- much more important than most of the techno-talk, unless your major interest is in engineering as opposed to image-making (not that there'd be anything wrong with that.)
But the only thing *I'm* personally curious about with the Foveon photos is their peculiar "look." As I've mentioned a couple of times, they look like watercolors to me. Is that because of Michael's post-processing, because of the particular subject matter he's been working with lately (countryside farm shots, a traditional watercolor subject) or is it the native "look" of the sensor? Is this look a result of what ndevlin calls "seriously inaccurate" colors? Are the colors really seriously inaccurate, and how? It seems to me (looking at the photos on my monitor, which may be different than anyone else's monitor) that they are not so much inaccurate, as muted -- to use painters' language, the hue is correct but the chroma is lower than on other cameras. Are the Bayer cameras simply the Velvia of digital photography, while the SD1 is the Provia? That would be different than "inaccurate," in that it would reflect a knowing choice, rather than an error.
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But the only thing *I'm* personally curious about with the Foveon photos is their peculiar "look." As I've mentioned a couple of times, they look like watercolors to me. Is that because of Michael's post-processing, because of the particular subject matter he's been working with lately (countryside farm shots, a traditional watercolor subject) or is it the native "look" of the sensor?
so why don't you just look through photos of people who were using Sigma cameras professionally for years instead of MR who albeit assisted and being a photographer himself still did not use that particular equipment and related postprocessing a lot ?
start w/ such popular destination as
www.x3magazine.com/
http://vstudio-magazine.de
www.rytterfalk.com
http://www.pbase.com/sigmadslr
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I accidentally shot my SD14 at ISO400 the other day in full sunlight. It was quite noisy even in bright conditions. And the noise was of a different type than you normally see. Instead of the familiar fine grained red and green speckles, there was a kind of filiamentary look at quite a large scale. I would call them blotches rather than speckles but even that isn't quite right. It look a bit like the large scale maps of the universe you see, showing the distribution of matter in the visible universe. Very uneven, with denser areas of noise then voids with no noise. Very different from Bayer noise patterns.
Sounds like heavy noise reduction is the culprit. I wonder if you shoot in JPG or RAW? And if in RAW, maybe you should try to do conversion with all NR off (if possible with the conversion program). A trick I sometimes use when I have to use over the top noise reduction is that after the fact I add some noise to the image on purpouse to make it feel more natural.
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To me, the most telling thing is how little chatter there has been about the reviews of the SD1.
why there should be any chatter about SD1 reviews and of all places here ? people who are interested know what Sigma cameras are, what to expect and they can download and try raw files... what in the world MR can tell 'em new about Sigma cameras or SPP raw converter ?
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The inaccuracy of the colour I have seen is in the reds. Beautiful colour, just not what the human eye perceives. Not sure how relevant the cause is. The only question is can it be fixed? Profiles would do it, probably. But SPP doesn't support those yet.
As for why no LR/ACR support.....let's all think whether it's in Adobe's interest to cut-out Sigma. They support every other camera on earth, and go out of their way to get pre-release versions to testers of new cameras, so I would bet considerable sums that they are not the source of the problem.
Lastly, I didn't mean to say that technically-oriented discussions don't have their place. I admire people who have that level of expertise in these complex technical areas. Rather, it's that these conversations seem inordinately dominant on the LL forums lately.
Of course, because no one is actually going to buy the camera, I guess it's not really fair to talk about real world photographic experience with it ;D Too bad. This technology clearly has potential. Not in the order of magnitude its evangelists suggest, but significant nonetheless. I deserves to be more than a footnote and a Harvard Business School How-Not-To case.
- N.
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At the risk of getting technical ;)
The only question is can it be fixed? Profiles would do it, probably.
Profiles would certainly be a step in the right direction, but there is a limit since the unusual spectral response of the SD1 color channels means pretty high metameric failure which profiles can never help.
As for why no LR/ACR support.....let's all think whether it's in Adobe's interest to cut-out Sigma. They support every other camera on earth, and go out of their way to get pre-release versions to testers of new cameras, so I would bet considerable sums that they are not the source of the problem.
I agree. However, the color processing for a Foveon sensor is far more involved than any Bayer sensor. It is very possible that it is not practical for Adobe to support this type of sensor with any color fidelity at all without drastically altering their color processing. It likely wouldn't be worth it for Adobe to do this even if Foveon was cooperative. That, if true, I suppose could be interpreted as being Adobe's "fault". Wild speculation of course. But really, the color processing for this type of sensor is incredibly different from Bayer processing and that may prove to be a significant burden on any RAW processor that considers their product's color performance to be important.
And yeah, like you said, at this price the only discussions worth having are academic ones because it's not like anyone is going to buy the camera...
Ken
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Those are not cameras for a serious professional workflow, not because of the sensor because we end with zillion layers anyway in this industry, but for many other factors that makes those cameras almost unusable in commercial maybe with the exception of weddings etc...
Seems very ill suited to weddings. Too slow an interface means missing shots. Weird color response combined with the weird lighting in so many wedding settings is a recipe for disaster (not to mention no profile support). Churning through a bazillion shots with very low profit margin means a speedy workflow which SPP decidedly is not!
Ken
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Nope. The economics of sensor wafer fabrication are such that th viable price depends on a good yield, which can really on be achieved after some significant production. Moreover, who is going to tool-up on a specifialized build like this for a few hundred sensors? No one, unless they are charging a fortune for the chip. I am confident that this is not the business model.
- N.
If you are confident this is not the business model, then please explain what you think is the business model. One has to credit the business managers of Sigma Corporation having at least a modicum of nous.
I understand that National Semiconductors and Dongbu Electronics are involved in the manufacture of the Foveon sensor.
If it is true these companies have 'tooled-up' to produce large quantities of this Foveon sensor, then it makes no sense whatsoever to charge such a high price for the camera.
The only sensible explanation I can think of is that it is now realised that yields, at least for the forseeable future, for whatever reason, are going to be low.
The reason could be that the manufacture of some essential component of the camera or the sensor has been disrupted by the tsunami in Japan, or that this particular design of Foveon sensor, with it's significantly higher resolution than previous designs, really is very expensive to manufacture.
It could be the case that some time ago there was a board meeting at Sigma Corporation where it was suggested that the project would have to be cancelled or at least delayed for a significant time because of the scarcity of certain essential components which would inevitably result in very small production runs.
Perhaps some bright spark in the boardroom suggested that an alternative to cancelling or delaying the project could be to sell whatever few units that could be assembled, at a sufficiently high price that would ensure demand equalled supply.
Got it? ;)
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Or maybe Sigma wants to raise money by demonstrating they can deliver a premium product?
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One has to credit the business managers of Sigma Corporation having at least a modicum of nous.
Why? What evidence do you have for that? The business world is full of incredibly awful ideas executed horribly by otherwise successful entities. Even from companies that are incredibly successful in other seemingly closely related sectors. Witness every Microsoft attempt at a smart phone.
The only sensible explanation I can think of is that it is now realised that yields, at least for the forseeable future, for whatever reason, are going to be low.
If that is the only "sensible explanation" you can think of you've obviously never worked with a marketing department regarding a consumer product. An equally "sensible explanation" is that someone there thinks they can distinguish themselves in the market by artificially inflating the price. This is in fact a valid and sometimes successful strategy, witness $250 designer T-shirts. It ain't going to work here for reasons a number of analysts have pointed out, but it isn't like we'd be surprised by a stupid marketing idea from Sigma.
Perhaps some bright spark in the boardroom suggested that an alternative to cancelling or delaying the project could be to sell whatever few units that could be assembled, at a sufficiently high price that would ensure demand equalled supply.
Yep, could be. But that is somewhat counter to how most people handle yield issues. From the little that I heard the pricing was a surprise to people involved in the design and manufacture, which seemed to indicate it was a marketing move more than anything else. But we are all on the outside and can only guess. Regardless, it is a dead product at this price.
Ken
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does "stunning" have any numbers or it is another "6 stops of DR" ?
It's a free program, so you can test it out yourself. I use LR3 for everyday stuff, but I export raws to RPP for printing. There is a big difference in detail.
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Why? What evidence do you have for that? Ken
The existence of the company is the evidence. Designer shirts are in a different category. They are products designed for irrational people. They are not bought on the basis of technical reviews of the durability or strength of the fabric, or the utility of the garment for particular purposes.
A large company like Sigma Corporation competing in the market place with complex and highly technical products would soon cease to exist if its marketing department were run by nincompoops. It is reasonable to assume that they know what they are doing, in the absence of evidence to the contrary; that is evidence that makes it clear there is no problem with regard to production costs or availablity of critical parts.
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Or maybe Sigma wants to raise money by demonstrating they can deliver a premium product?
They have got a premium product in at least one sense, which we've discussed before. The SD1 is the highest resolving cropped format sensor currently on the market.
If I were a keen bird and wildlife photographer, I might consider that an SD1 with Sima 800mm F5.6 is a better option than a Canon 7D or 60D with the same lens. Whether or not the extra detail and resolution is worth an additional $5,000 cannot be decided until we see properly controlled comparisons between the 18mp Canon and the 30mp SD1 using the same lens.
I personally would not be happy that the Sigma 800/F5.6 does not have image stabilisation. The new Canon 800/5.6 does. However, that lens is much more expensive than the Sigma. In fact, the combination of a Canon 7D with Canon 800/F5.6 IS lens would be more expensive than the Sigma 800/5.6 with SD1.
As I understand, the Foveon sensors appear to resolve beyond the Nyquist limit on test charts. That might be a good thing when photographing feathered birds. Such feathers might appear sharper as a result of artificial detail. Photography is all about appearance for most people.
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A large company like Sigma Corporation competing in the market place with complex and highly technical products would soon cease to exist if its marketing department were run by nincompoops. It is reasonable to assume that they know what they are doing, in the absence of evidence to the contrary; that is evidence that makes it clear there is no problem with regard to production costs or availablity of critical parts.
But the "evidence to the contrary" IS the SD1 pricing. You're saying that we should look at everything else (which we don't know much about) to determine whether the SD1 pricing is stupid. It's possible that their prices on everything else are brilliantly calculated; nevertheless, the pricing on the SD1 is dumb. It's so strange, in fact, I'll occasionally think I've come up with a justification. Then I think, "No, that can't be it..." I thought perhaps that they put the price so high to attract attention, planning then to lower the price, so everybody would jump on the newly repriced cameras as great bargains. But then...that'd do nothing but piss off all the early buyers, their most loyal customers. So, you know...no. Maybe they'll give the money back? No...
Major companies, as other people have said, screw up all the time. A couple of years ago, Microsoft killed what seemed to be one of the most innovative tablet/pad computers ever thought of...I think it might have been called the Courier, or something like that...because the market just wasn't ready for pads. We know how that worked out...for Apple.
JC
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But the "evidence to the contrary" IS the SD1 pricing. You're saying that we should look at everything else (which we don't know much about) to determine whether the SD1 pricing is stupid. It's possible that their prices on everything else are brilliantly calculated; nevertheless, the pricing on the SD1 is dumb. It's so strange, in fact, I'll occasionally think I've come up with a justification. Then I think, "No, that can't be it..." I thought perhaps that they put the price so high to attract attention, planning then to lower the price, so everybody would jump on the newly repriced cameras as great bargains. But then...that'd do nothing but piss off all the early buyers, their most loyal customers. So, you know...no. Maybe they'll give the money back? No...
Major companies, as other people have said, screw up all the time. A couple of years ago, Microsoft killed what seemed to be one of the most innovative tablet/pad computers ever thought of...I think it might have been called the Courier, or something like that...because the market just wasn't ready for pads. We know how that worked out...for Apple.
JC
I've just given you a perfectly reasonable explanation. The Sigma Corporation has been faced with the choice of cancelling or delaying the release of their product due to unforseen circumstances, such as a shortage of critical components, or unforseen production expenses. Perhaps one supplier of a critical component, that had its factory destroyed in the Japanese tsunami, or simply went bankrupt, had already produced 1,000 units of that critical component.
Sigma is therefore only able to sell 1,000 cameras until such a time as a new supplier of such critical component can be found. They've therefore decided, out of the generosity of their heart, to make those few cameras available at a premium price, to those who are interested and who often spend $250 on a designer shirt without thinking twice. ;D
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Hi,
Ray I'd suggest that this is a good point.
Best regards
Erik
As I understand, the Foveon sensors appear to resolve beyond the Nyquist limit on test charts. That might be a good thing when photographing feathered birds. Such feathers might appear sharper as a result of artificial detail. Photography is all about appearance for most people.
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Why? What evidence do you have for that? The business world is full of incredibly awful ideas executed horribly by otherwise successful entities. Even from companies that are incredibly successful in other seemingly closely related sectors. Witness every Microsoft attempt at a smart phone.
Ken
You are wrong on this one. We were in Europe for two weeks in early June and I got a Verizon loaner since my Droid Incredible only works in the US. They gave me a HTC with the latest MSFT mobile operating system and it worked like a charm. No dropped calls, e-mail, and Internet access; the interface was clean and straightforward. I realize that there are a lot of AAPL-proselytizers on LuLa, but don't go making blanket statements that are untrue.
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I don't understand why people keep inventing reasons why the SD1 is priced the way it is.
In my article, Rationalizing The Irrational (http://www.luminous-landscape.com/essays/rationalizing_the_irrational.shtml) I wrote.. "There can be no doubt that a senior executive within the Sigma organization decided that they had a winner with the SD1's image quality and that it could therefore command a premium price.
It was not chip yield, manufacturing or supply issues, the earthquake, or any other seemingly plausible reason. It was just a misguided decision by one executive that flabbergasted the rest of the company. It was a really bad decision and I predict will one day become something of a business school case study. Call in the King Lear syndrome.
Michael
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You are wrong on this one. We were in Europe for two weeks in early June and I got a Verizon loaner since my Droid Incredible only works in the US. They gave me a HTC with the latest MSFT mobile operating system and it worked like a charm. No dropped calls, e-mail, and Internet access; the interface was clean and straightforward. I realize that there are a lot of AAPL-proselytizers on LuLa, but don't go making blanket statements that are untrue.
I think you misunderstood what I was referring to. Actual phones, not operating systems. The HTC is not a Microsoft phone, it uses a Microsoft OS but is not made by Microsoft. The KIN was a disaster and was an actual MS phone. They also managed to kill the very successful SideKick line after acquiring Danger.
You are emphasizing my point exactly - Microsoft has a functional OS for phones that is competing in the marketplace. Seems like they should be able to make their own phone and market it - and yet the KIN is probably the biggest technology failure in the market place in a long time.
That was what I was referring to, sorry if I wasn't clear enough.
Ken
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If you are confident this is not the business model, then please explain what you think is the business model. One has to credit the business managers of Sigma Corporation having at least a modicum of nous.
In my line of work, the drawing of an inference unsupported any facts is an error of law. You presume there is a rationality at work here beyond someone at Sigma reading their own propaganda about the camera and deciding that, since it was obviously a medium-format quality camera it should be priced as such.
Everything publicly known in this case is consistent only with a catastrophically bad decision made in such a way, or by such individuals, that a reversal is not possible within the confines of Japanese business culture.
I'll be blunt: the SD1 is stillborn. If the price is not lower to +- $2200 within 6 months, it will be a complete business failure, and quite possibly the end of the line for the Foveon project for the foreseeable future.
- N.
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I don't understand why people keep inventing reasons why the SD1 is priced the way it is.
Probably, Michael, because some of us find it difficult to believe that any senior executive in a major organisation, who is responsible for setting the recommended retail price of a complex piece of equipment, would not have a rational reason for any pricing decision made, such as reference to market research suggesting a significant number of potential buyers would be prepared to pay such a price.
Call me naive if you like :) .
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I don't understand why people keep inventing reasons why the SD1 is priced the way it is.
In my article, Rationalizing The Irrational (http://www.luminous-landscape.com/essays/rationalizing_the_irrational.shtml) I wrote.. "There can be no doubt that a senior executive within the Sigma organization decided that they had a winner with the SD1's image quality and that it could therefore command a premium price.
It was not chip yield, manufacturing or supply issues, the earthquake, or any other seemingly plausible reason. It was just a misguided decision by one executive that flabbergasted the rest of the company. It was a really bad decision and I predict will one day become something of a business school case study. Call in the King Lear syndrome.
Michael
Yes, I had the same info. It should have been at the highest level, not just any executive but on the head of the company. Sigma hasn't correct that much the situation neither gave press conference, apologyzed, fired nobody that we know like normaly would happen if "someone" would have done such a mistake. This, smells that the "executive" in question could be nothing less than the maximum responsable, the number 1.
I don't know it for sure and Michael will not talk (although in between lines we read), but it appears to me and others that this mistake takes its source on the very top. It's a "désir de grandeur" whim.
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Probably, Michael, because some of us find it difficult to believe that any senior executive in a major organisation, who is responsible for setting the recommended retail price of a complex piece of equipment, would not have a rational reason for any pricing decision made, such as reference to market research suggesting a significant number of potential buyers would be prepared to pay such a price.
Call me naive if you like :) .
There are plenty of senior executives who make bad decisions for bizarre reasons. It may not necessarily be commonplace but it is definitely not rare. In my previous career in software development of 25 years duration, I saw it several times first hand. I don't know if you're naive but what shade of rose are those glasses you wear? :) :)
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There are plenty of senior executives who make bad decisions for bizarre reasons. It may not necessarily be commonplace but it is definitely not rare. In my previous career in software development of 25 years duration, I saw it several times first hand. I don't know if you're naive but what shade of rose are those glasses you wear? :) :)
I can appreciate there are lots of bad decisions made in hindsight, by senior executives, politicians and each and every one of us. We're a bungling species.
What often happens is that a decision has to be made at a particular time despite the lack of full information. Because we can't always predict the future, it often turns out a particular decision was bad with the benefit of hindsight.
However, if you have examples of senior executives making decisions for bizarre reason, then describe a few. Perhaps such executives were drunk at the time, or in love, appointing their mistresses to senior positions.
A reason for a particular decision may sometimes seem bizarre because we're not in possession of the full circumstances affecting the decision.
For all I know, Sigma executives might have been ready to announce an agreed price of $2,000 (or less) for the SD1, when it was revealed through the grapevine, or company spies, that Canon is soon to unveil a 30mp cropped format camera with improved high ISO performance, improved video and a few other useful features which the SD1 doesn't have.
In other words, the SD1 would soon be dead in the water even at a $2,000 price. Perhaps a $7,000 price tag was designed to minimise the losses.
I'm just speculating of course.
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Ray - I have three words of advice on this topic... Remember Occam's Razor.
Michael
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But it is rumored that Occam occasionally cut himself while shaving.
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Ray - I have three words of advice on this topic... Remember Occam's Razor.
Michael
Yes, I remember it quite well, Michael. I often listen to the weekly Science program on ABC National Radio. (That's the Australian Broadcasting Corporation, not the American Broadcasting Corporation)
But my understanding is, in order to apply Occam's Razor, one has to be aware of the competing theories before one can choose the simplest.
We've ruled out the Japanese tsunami. Perhaps we've ruled out unforseen and 'expensive-to-rectify' problems at the manufacturing stage. Have we ruled out the imminent arrival of a 'killer' camera from Canon?
My imagination is fertile on this topic, but I have no wish to have the topic closed because of libelous scenarios that I might innocently create. :)
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A warm thank you to Michael and Nick for doing a great review and Michaels commentary on the SD1's insane pricing. Spot on IMHO
Sigma must be very serious about this camera if they loaned Lawrence and a selection of their best lenses for the review.
I have been shooting with a SD14 for three years and Nikon D70/90 for six years. I do not make my living with my cameras but derive a lot of joy for family and friend with my results.
The bottom line for me is no matter how refined and competent my Nikon gear is I cannot produce the visually stunning shots I get out of the Sigma. My wife can see the difference, their is something special about the photos I get from the X3 sensor. Their is a realism that we lost with film becoming unpractical for regular folks today many call it Sigmachrome. If it were not for those redeeming qualities my SD14 would have been at the bottom of the Columbia River or sold for pennies on the dollar because as a piece of equipment to shoot with it is a bag of hurt.
Many say the SD15 is much improved functionally, what the SD14 should have been in the first place. But call me spoiled, I am too used to getting more when I upgrade my gadgets, like 2x the computing power.
I would be figuring out the SD1 today if it were not for the D3x size price, I have to work for my money and raise 3 kids.
Sigma's camera's are not at the point where they can be the be all for every body, when shooting sports, theatre, or general junk the Nikon gets the nod, something special like landscape, portraits, trains(I am a railfan) the Sigma gets the nod.
BTW I don't know where folks get the lack of color sensitivity or lack of DR I find that to be the opposite. Shooting on a cloudy day with the SD14 is truly a joy in its own right.
Paul M. Petersen
my gallery
www.peterzpicts.smugmug.com
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If you are confident this is not the business model, then please explain what you think is the business model. One has to credit the business managers of Sigma Corporation having at least a modicum of nous.I understand that National Semiconductors and Dongbu Electronics are involved in the manufacture of the Foveon sensor.
If it is true these companies have 'tooled-up' to produce large quantities of this Foveon sensor, then it makes no sense whatsoever to charge such a high price for the camera.
The only sensible explanation I can think of is that it is now realised that yields, at least for the forseeable future, for whatever reason, are going to be low.
The reason could be that the manufacture of some essential component of the camera or the sensor has been disrupted by the tsunami in Japan, or that this particular design of Foveon sensor, with it's significantly higher resolution than previous designs, really is very expensive to manufacture.
It could be the case that some time ago there was a board meeting at Sigma Corporation where it was suggested that the project would have to be cancelled or at least delayed for a significant time because of the scarcity of certain essential components which would inevitably result in very small production runs.
Perhaps some bright spark in the boardroom suggested that an alternative to cancelling or delaying the project could be to sell whatever few units that could be assembled, at a sufficiently high price that would ensure demand equalled supply.
Got it? ;)
Edsel, anyone?
Rob C
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A warm thank you to Michael and Nick for doing a great review and Michaels commentary on the SD1's insane pricing. Spot on IMHO
Sigma must be very serious about this camera if they loaned Lawrence and a selection of their best lenses for the review.
I have been shooting with a SD14 for three years and Nikon D70/90 for six years. I do not make my living with my cameras but derive a lot of joy for family and friend with my results.
The bottom line for me is no matter how refined and competent my Nikon gear is I cannot produce the visually stunning shots I get out of the Sigma. My wife can see the difference, their is something special about the photos I get from the X3 sensor. Their is a realism that we lost with film becoming unpractical for regular folks today many call it Sigmachrome. If it were not for those redeeming qualities my SD14 would have been at the bottom of the Columbia River or sold for pennies on the dollar because as a piece of equipment to shoot with it is a bag of hurt.
Many say the SD15 is much improved functionally, what the SD14 should have been in the first place. But call me spoiled, I am too used to getting more when I upgrade my gadgets, like 2x the computing power.
I would be figuring out the SD1 today if it were not for the D3x size price, I have to work for my money and raise 3 kids.
Sigma's camera's are not at the point where they can be the be all for every body, when shooting sports, theatre, or general junk the Nikon gets the nod, something special like landscape, portraits, trains(I am a railfan) the Sigma gets the nod.
BTW I don't know where folks get the lack of color sensitivity or lack of DR I find that to be the opposite. Shooting on a cloudy day with the SD14 is truly a joy in its own right.
Paul M. Petersen
my gallery
www.peterzpicts.smugmug.com
Well I think you hit the point Paul,
your post actually shows that you owned a Foveon and been working with it, and print, for years, wich again is very different than the tech analysis based on theory and not real practise.
Yes, I also found a better DR when I had the SD14 (and people jumped on me here claiming the DoX graphs etc...) but this notion of DR is a vast field of muddy waters and a land of endless speculations from people who actually never worked with the cameras they discuss but just reading curves on some websites.
Lots of people take a gear measurement and say this or that has X points of DR. That is completly useless. It's exactly like saying that the average year temperature in Madrid capital is 20 grades.
That does not give you any indication is winters are cold and summer very hot, or if it's 20 the all year etc...
DR is linked to Isos. So yes the Foveon at base isos has a great amount of DR, but it falls apart very fast when you increment the isos. It is a weired behaviour but that's what the eyes and the prints are saying and not a general number taken isolated from the context. The numbers can talk all they want to, the ultimate truth is what our eyes are seeing and the prints are saying and I agree with all your lines.
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My SD14 produces dreadful results in LR by default - as horrible green cast over everything. Looking around at other SD14 users, it appears all the cameras have this cast in variable amounts. Rumour has it that Sigma profiled each Sd14 in the factory and burned a correction into firmware. SPP can read the correction information, LR can't. Certainly, SPP was much better than LR at producing acceptable default colour.
A couple of months ago I got a colour checker passport and made my own custom DNG profiles. The colour is transformed, the cast is gone. I tried the same trick with my SD9 which has a tendency to yellowness I don't like -with much less success. I think Foveon have gradually improved colour with each iteration of the sensor. The rest is software. The SD1 is a new chip design so we may have rebooted to the beginning of the cycle again as they learn how to control the colour. Or it might simply be software that was rushed to market and there is much more neutral colour potential in the camera.
At the risk of getting technical ;)
Profiles would certainly be a step in the right direction, but there is a limit since the unusual spectral response of the SD1 color channels means pretty high metameric failure which profiles can never help.
I agree. However, the color processing for a Foveon sensor is far more involved than any Bayer sensor. It is very possible that it is not practical for Adobe to support this type of sensor with any color fidelity at all without drastically altering their color processing. It likely wouldn't be worth it for Adobe to do this even if Foveon was cooperative. That, if true, I suppose could be interpreted as being Adobe's "fault". Wild speculation of course. But really, the color processing for this type of sensor is incredibly different from Bayer processing and that may prove to be a significant burden on any RAW processor that considers their product's color performance to be important.
And yeah, like you said, at this price the only discussions worth having are academic ones because it's not like anyone is going to buy the camera...
Ken
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According to DPReview's tests, the Foveon sensor has better highlight range but worse shadow detail/noise than is typical. So I guess with bright skies and the like it might look like DR is better because it preserves highlight detail. Until you examine the shadows...
Well I think you hit the point Paul,
your post actually shows that you owned a Foveon and been working with it, and print, for years, wich again is very different than the tech analysis based on theory and not real practise.
Yes, I also found a better DR when I had the SD14 (and people jumped on me here claiming the DoX graphs etc...) but this notion of DR is a vast field of muddy waters and a land of endless speculations from people who actually never worked with the cameras they discuss but just reading curves on some websites.
Lots of people take a gear measurement and say this or that has X points of DR. That is completly useless. It's exactly like saying that the average year temperature in Madrid capital is 20 grades.
That does not give you any indication is winters are cold and summer very hot, or if it's 20 the all year etc...
DR is linked to Isos. So yes the Foveon at base isos has a great amount of DR, but it falls apart very fast when you increment the isos. It is a weired behaviour but that's what the eyes and the prints are saying and not a general number taken isolated from the context. The numbers can talk all they want to, the ultimate truth is what our eyes are seeing and the prints are saying and I agree with all your lines.
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According to DPReview's tests, the Foveon sensor has better highlight range but worse shadow detail/noise than is typical. So I guess with bright skies and the like it might look like DR is better because it preserves highlight detail. Until you examine the shadows...
Yes, the "gain" is indeed in the highlights. At based isos I could not see the degradation in the shadows but yes, when increment the isos, the reduction of DR in the shadows was more pronounced than with the Bayer and fall apart very fast.
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Some great observations above. Laughed till I cried about the SD14 being a "a bag of hurt" as a camera.
And that really captures it. A camera might be somewhat better in some respect, but the quality at all levels is now so damn close that the real question is not is it better, but is it better enough to bother?
There's a reason serious pros generally use Nikon and Canon. It's just easier to shoot with, and whatever tiny percentage of 'improved' IQ one might get from a Sigma, or a Leica or an MF camera is vastly outweighed by the imperative of getting the shot. A focused, publishable image with ideal composition is far more valuable than a less well-composed image taken a split second after the decisive moment, possessing 30% more resolution or a hint more DR.
Integrating oneself with one's tools is the most important step in mastery of the art-form. Not the tools themselves. That's why the user-experience is SO important on cameras, compared even to IQ, which is now a game of inches.
On this front, Sigma has far to go. I wish them well on the journey, but they are not currently doing anything to help themselves.
- N.
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DR is linked to Isos. So yes the Foveon at base isos has a great amount of DR, but it falls apart very fast when you increment the isos.
The DR can only drop by maximum of one stop per each doubling of the ISO. If shooting at a higher ISO for some reason were to drop the DR more, one should never shoot in that ISO, but just push in post processing - doing pushing is post causes one stop loss for each ISO stop pushed.
(Surprisingly losing a stop per level of ISO is actually better than it dropping less as that would indicate problems in ADC or elsewhere late in the imaging pipeline.)
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BTW I don't know where folks get the lack of color sensitivity or lack of DR I find that to be the opposite. Shooting on a cloudy day with the SD14 is truly a joy in its own right.
Well, the folks get it from science - observations and measurements. Using silicon's wavelength dependent photon absorption will lead to very weak color separation. This is one of the reasons why Foveon images are noisy without plenty of noise reduction. The dynamic range is very limited because of noise - the 3T photodiode used by Foveon sensor is noisy as there is no way for it to eliminate reset noise (through correlated double sampling). No other manufacturer used 3T, but typically some 4T variant. To add to the insult of 3T high noise, all the three layers require their own 3T set.
I am happy you like your SD14 and if you feel it has good colors and high DR for your purpouses, great, but compared to other cameras it is lacking lots on both.
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According to DPReview's tests, the Foveon sensor has better highlight range but worse shadow detail/noise than is typical. So I guess with bright skies and the like it might look like DR is better because it preserves highlight detail. Until you examine the shadows...
DPR doesn't measure dynamic range in any sensible way. They use some arbitary tone curves with arbitary mid grey point (or set by camera), and they eyeball the results they get.
Anyhow, what happens if we expose a camera stop less and then use a different tone curve? We get a stop more headroom, do we not? At DPR they don't realize that their measurements are rather silly when they separate head- and footroom. Dynamic range is the whole range, not one part here and other part there. How much of this dynamic range is used for headroom and footroom is depends totally on the photographer, it is not fixed in some way as DPR presents it.
AFAIK, the Sigma cameras have a tendency of exposing somewhat less than the competition if one applies no exposure compensation. This leads to different headrooom/footroom ratio than what the competition will achieve if one lets the camera to decide the exposure. But I must emphasize that this has nothing to do about the magnitude of the dynamic range itself.
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Lots of people take a gear measurement and say this or that has X points of DR. That is completly useless. It's exactly like saying that the average year temperature in Madrid capital is 20 grades.
That does not give you any indication is winters are cold and summer very hot, or if it's 20 the all year etc...
DR is linked to Isos. So yes the Foveon at base isos has a great amount of DR, but it falls apart very fast when you increment the isos. It is a weired behaviour but that's what the eyes and the prints are saying and not a general number taken isolated from the context. The numbers can talk all they want to, the ultimate truth is what our eyes are seeing and the prints are saying and I agree with all your lines.
please do not mix "average" w/ "maximum"... for 4.6 x 3 mp Foveon sensor the company itself published DR numbers and that will be a little over 10stops, not even 10.5
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My SD14 produces dreadful results in LR by default
you may be noticed that Adobe does not include their DNG profiles for Sigma cameras at all (no .dcp files - everything is hardcoded and probably was not changed or verified for ages).
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DPR doesn't measure dynamic range in any sensible way. They use some arbitary tone curves with arbitary mid grey point (or set by camera), and they eyeball the results they get.
Anyhow, what happens if we expose a camera stop less and then use a different tone curve? We get a stop more headroom, do we not? At DPR they don't realize that their measurements are rather silly when they separate head- and footroom. Dynamic range is the whole range, not one part here and other part there. How much of this dynamic range is used for headroom and footroom is depends totally on the photographer, it is not fixed in some way as DPR presents it.
AFAIK, the Sigma cameras have a tendency of exposing somewhat less than the competition if one applies no exposure compensation. This leads to different headrooom/footroom ratio than what the competition will achieve if one lets the camera to decide the exposure. But I must emphasize that this has nothing to do about the magnitude of the dynamic range itself.
Agreed. Whether more range is in the highlights or shadows is just up to how the camera meter is calibrated and how the shooter uses it.
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Hi,
Well, my view is that the ETTR (Expose To The Right) maximises utilisation of DR. ETTR essentially mean that exposure is maximized still avoiding clipping.
Best regards
Erik
Agreed. Whether more range is in the highlights or shadows is just up to how the camera meter is calibrated and how the shooter uses it.
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The default profile for the SD14 is described as "Embedded". I believe the earlier versions of LR must not have supported DNG for Foveon (I read a support forum post to this effect from Thomas Knoll) but if definitely does now. I have four different profiles for my SD14 and they all produce different renderings. Thankfully because I couldn't put up with SPP. It's not a terrible program like Michael suggests and would be perfectly fine if Sigma were your only camera and you were happy to use a basic raw converter then finish up in Photoshop. But not if you want to preserve a single all raw workflow.
you may be noticed that Adobe does not include their DNG profiles for Sigma cameras at all (no .dcp files - everything is hardcoded and probably was not changed or verified for ages).
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I can say from my experience with the SD14 Sigma is well aware of the need to expose to the right, so much so I feel the meter is too easily spooked by shadows and will blow the highlights under certain situations and ruining shots.....grrr.
As far as shooting, Dynamic range means to me having details in the highlights and the shadows. Playing with the x3 fill light I am able to stretch shots a lot further without having them look silly than I can with my D90 files a camera well regarded for its DR in the segment.
As far as work flow, I found getting good color out of SPP very hard prior to version 4. Back then I used LR and ACR and was able to correct colors easier than chasing my tail coming out of SPP.
Since SPP4 I do all my conversion their and buff and polish in Photoshop Elements, I have found the easiest tool to kill the dreaded green cast is to play with the mid tones in the green level channel, .95 usually does the trick for my camera. After that its just a matter of RGB level adjustment and final dose of mild USM.
Happy Snappin,
Pete
www.peterzpicts.smugmug.com
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Paul,
That SD14 is one bag of hurt! I've shot with Sigma's dSLRs beginning with the SD10, and in many ways the SD14 was a step backwards. The SD15 is the 'good twin' to the SD14: much better color, great battery life, better ergonomics, and overall a much easier camera to shoot with than it's evil twin. My experience mirrors yours with Nikon and Canon's---the images from my SD15 (and previous versions) are just more satisfying to work with. For me, I'm able to get to a finished print much faster. And like you, I was expecting the SD1 to be a worthy (and flawed) upgrade for my SD14, for a reasonable ($2K) price. Oh well, they missed the mark on that
I find Sigma Photo Pro to be an interesting software package. The Fill Light (a single slider for tone mapping) is brilliant. Most of the controls are reasonable, and I don't miss a lot of other functionality (I take my photos to finish in Lightzone or PS). But in working with SPP5 and SD1 files? Ugh. They've got a bit more coding to do to make it bearable.
Making individual images can be a real delight with the SD15. But if I had to do event work on a deadline with a serious workflow---I wouldn't ever consider the camera (or an SD1 at this point).
Jim
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As many of you know, I've been quite voluble in expressing skepticism about the 'qualitative' advantages of MFDB as regards its 3-dimensionality and extra crispness due to the lack of an AA filter.
Such qualities are clearly discernible, and I wouldn't deny they exist. But the price premium one has to pay for an MFDB system is a bit offputting, to put it mildly, not to mention the disadvantages of additional weight and general cumbersomeness of the system.
In a sense, it is therefore surprising that those who are already 'sold' on the 3-dimensionality of the MFDB and the additional 'crispness' of the images, should criticise the pricing of the SD1.
I get the impression, but correct me if I'm wrong, that the Foven design not only has the benefit of no AA filter, but the benefit of 'no need' to interpolate (or invent) image information because of the unequal balance between the number of red, green and blue diodes that the Bayer system has to contend with.
The 'qualitative' benefits of the Foveon system in this respect, disregarding pixel count, should exceed the qualitative benefits of MFDB.
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As many of you know, I've been quite voluble in expressing skepticism about the 'qualitative' advantages of MFDB as regards its 3-dimensionality and extra crispness due to the lack of an AA filter.
Such qualities are clearly discernible, and I wouldn't deny they exist. But the price premium one has to pay for an MFDB system is a bit offputting, to put it mildly, not to mention the disadvantages of additional weight and general cumbersomeness of the system.
In a sense, it is therefore surprising that those who are already 'sold' on the 3-dimensionality of the MFDB and the additional 'crispness' of the images, should criticise the pricing of the SD1.
I get the impression, but correct me if I'm wrong, that the Foven design not only has the benefit of no AA filter, but the benefit of 'no need' to interpolate (or invent) image information because of the unequal balance between the number of red, green and blue diodes that the Bayer system has to contend with.
The 'qualitative' benefits of the Foveon system in this respect, disregarding pixel count, should exceed the qualitative benefits of MFDB.
Ray,
I don't understand, and it's not aimed to you, why people are seeing the grail to interpolate. They want reso on the cheap. It doesn't work like that. The SD1 is a stunning 15MP camera, and a good 20 ish MP interpolated. If you really want to take all the benefits of the Foveon you need to use the camera at its based resolution.
The moment you interpolate you loose quality, even if in the case of the Foveon you loose less in interpolation, you loose anyway.
You can say that after all it is a good performance that a 15MP camera would deliver a similar output of a 20ish MP bayer, yes, but where is the Foveon advantage then?
Well, the real advantage of the Foveon is that if you take 2 15MP cameras, the Sigma will be truly outstanding, but if you interpolate you'll end in a similar result of the Bayer. If you want to see the "miracle" Sigma is claiming, you need to keep the camera in its resolution wich is 15MP and compared it to other similar cameras on the market: the K5, the 7D etc...
15 packed in a small surface area is not the P65, not even a 20MP digital back. I think it's time to stop dreaming even if it's nice, even if it has 3 layers.
People want to see a sort of MF packed in a dslr... no, the Sigma is NOT the Leica S. It is very far, light years away in all aspects (sensor, built quality, features, image quality, value, image, pro service, lenses).
It's even far away from the Sony body wich is a truth pro body or the Leica M where you can mount on it the best glasses produced on earth.
So, if the Sigma had a large format sensor, it would probably smoke MF gear, but the fact is that it has not.
Also, the price, at that price or you have a brand that smells luxury and quality, or you get pro features. The SD1 does not have any of those.
People would like to feel that they finaly have MF quality for less than 8000euros and that the Robin Wood of the saga is Sigma. They might have a really big disapointment if they beleive so and sign the check.
It's like this sign I saw one day when walking on the beaches district in Toronto: swim at your own risk
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"I get the impression, but correct me if I'm wrong, that the Foveon design not only has the benefit of no AA filter, but the benefit of 'no need' to interpolate (or invent) image information because of the unequal balance between the number of red, green and blue diodes that the Bayer system has to contend with."
Benefit or curse though? Depends what you're shooting and your personal aesthetic preference or not for aliasing. The lack of OLPF is not a Foveon thing per se, as Michael had the good sense to round up some OLPF-less Bayer CFA cameras for comparison. If you want no OLPF, but a compact non-MF form factor there are choices to be had.
As for the lack of interpolation - there is no lack of interpolation. The chroma all has heavy NR applied which is absolutely inventing new (less noisy) image data. Indeed, the image processing necessary to turn a raw Foveon image to a nice RGB image is more complex and more intensive than is used to turn a Bayer mosaic image to RGB. I'd contend there's more interpolation going on for Foveon images than for Bayer. The argument that in Foveon there's no interpolation is false.
Graeme
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I get the impression, but correct me if I'm wrong, that the Foven design not only has the benefit of no AA filter, but the benefit of 'no need' to interpolate (or invent) image information because of the unequal balance between the number of red, green and blue diodes that the Bayer system has to contend with.
The 'qualitative' benefits of the Foveon system in this respect, disregarding pixel count, should exceed the qualitative benefits of MFDB.
People talking about the need to "invent" or "interpolate" color information in Bayer sensors vs the "true" pixels in Foveon sensors tend to rely on home-grown (or PR-driven?) theories that tend to be less relevant and obscure the understanding rather than enlighten. Not saying that you are, just explaining why "interpolated Bayer pixels" tends to set off my mental warning lamps. Even though I use theories every day, I really think that the IQ of image sensors should be finally judged by a sound collection of representative side-by-side test images judged by our eyes.
The AA-filter used in cameras and CD-recorders is a cost-adding component that is added for a reason. Canon and Sony does not add to their costs unless they think that it will increase sales. Some might disagree and prefer the unfiltered sampling, but that is a subjective thing. The basic theory behind was well understood when I was in University some years ago.
-h
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Where did you learn that SD1 is gong to get the DxOMark treatment? I couldn't find such information on their site, but didn't really dig deep ;) If true, it sounds interesting.
Look here (http://media.dxomark.com/index.php/Cameras/Camera-Sensor-Database/Sigma/SD1).
Of course, DXO does not test resolution so we will have to look elsewhere for those results.
Regards,
Bill
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Benefit or curse though? Depends what you're shooting and your personal aesthetic preference or not for aliasing.
Exactly! However, what some people may recognise as aliasing, or false detail, other less expert viewers may find pleasing, even startling in its crispness.
As for the lack of interpolation - there is no lack of interpolation.
There is a lack of interpolation in the sense that there are real values of red, blue and green for each pixel as opposed to two values of green for each pair of red and blue in the Bayer array, and the description of any one of those values as a whole pixel.
To put it another way, a 15mp Bayer array sensor gathers 15 million separate values of red green and blue. A 15mp Foveon sensor gathers 45 million separate values of red, green and blue. That's not an insignificant difference.
Of course I understand there are some diadvantages related to the absorption characteristics of the silicon. It's not an ideal color filter, and high ISO is rather noisy in the Foveon sensor compared with the best Bayer array sensors, but MFDB is also notorious for poor performance at high ISO. That doesn't stop MFDB owners from drooling over the extra crispness and intangible 3-dimensionality of their images.
I'll always remember my amazement when I first learned, in the days when I was still shooting film, that a 3mp digital camera has only 3 million separate color values, even though the image file ends up being 9MB. That's a hell of a lot of interpolation, I thought. In fact, as I recall, impressions of cheating and dishonesty passed through my mind. I remember being disappointed.
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The default profile for the SD14 is described as "Embedded".
exactly - it is hardcoded in the code
I believe the earlier versions of LR must not have supported DNG for Foveon (I read a support forum post to this effect from Thomas Knoll) but if definitely does now.
yes, only since ACR 6.3 RC :)
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Ray, what does it matter if you start off with a unique value for each of RGB at a single location if you then don't pass those unique values through to the final image because they're too noisy to use as-is? Noise Reduction is an interpolation process where we try to figure out what the under-lying noise free signal is from (spatially) multiple noisy samples. Figuring out a new value from a spatially diverse set of samples is exactly what you do in a demosaic process too. Both are interpolation, and "interpolation" is not a bad word in my book, although it is often used pejoratively. Almost everything we do in image processing to generate a pleasing image from raw data is some form of interpolation. In many demosaic algorithms the existing samples are passed though as is, meaning 1/3 of the final RGB values have not been interpolated. In the Foveon raw process, (if we assume for the moment, giving them the benefit of the doubt) the chroma pixels are all noise reduced and hence are not the originally captured values, so 2/3s of the final RGB are interpolated - leaving 1/3 that have not been.
The process of turning a Foveon raw into an image is at least as "inventive" as what goes on in a Bayer demosaicing process - you're just trading more precise, but lower spatial chroma data for higher amount of lower precision chroma data.
I must admit though, I find the "Foveon" name funny, because the fovea of the eye uses a spatial array for the LMS cones more like a Bayer pattern than a layered film-like approach.
Graeme
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A combination of the Foveon technology in a Bayer pattern matrix will be a phenomenal beast, wouldn't it? Now why didn't Sigma think of that?
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Ray, what does it matter if you start off with a unique value for each of RGB at a single location if you then don't pass those unique values through to the final image because they're too noisy to use as-is?
Graeme
Graeme,
The results indicate it matters a lot. A 15mp Foveon sensor provides more detail, or at least an impression of more detail and better micro-contrast, than any existing cropped-format DSLR on the market. According to Michael's article, the SD1 provides marginally more detail than the 24mp Sony A900.
Some of the images from an SD1 owner at Dpreview look stunningly sharp to me. I'm reminded of certain comparisons between MFDB and 35mm DSLRs that used to be the source of endless debate on this forum, except the differences from the SD1 seem to be greater in terms of micro-contrast.
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Ray, so it sounds like you like the look of no OLPF. If colour accuracy is not an issue for you, and you generally shoot at low ISO where noise is less of an issue, then great. Other thing you can do is shoot with a higher resolution Bayer CFA camera and downsample it - that can induce the same kind of lack-of-OLPF look you like (depending on choice of downsampling filter), could also lead to still lower noise.
Sudhakaran, the problem with Foveon is is not that it samples RGB at the same spatial point, but that to enable it's sampling of RGB at the same point it uses silicon thickness as a colour filter and that leads to poor and noisy colour. With a Bayer CFA you get good colorimetry and lower noise, but you sacrifice the layered arrangement. With Bayer CFA you can always produce a sharper image and the appearance of spatially co-located colour through downsampling. With Foveon there's very little that can be done about the colour.
Graeme
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Supposing - just supposing - that you didn't actually want colour at all, but black and white.
Which sensor type would give you the best starting point for B/W conversion - Beyer, or Foveon?
John
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John, I don't think there's a simple answer there. I'd always said we should have answered the eternal question: "What's black and white and red all over?" with a RED camera without the colour filters on the sensor. Then you'd use colour filters just as you'd shoot with black and white film. That would be the lowest noise solution.
With a Bayer CFA, you can post-choose your colour filter from careful blending of the RGB channels. This makes for good results and Bayer CFA cameras tend to have better noise and ISO performance - better dynamic range.
With a Foveon by shooting for black and white, you throw away it's one advantage, it's co-sited colour, but you get it's noise and ISO performance disadvantages.
Graeme
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Regarding what Graeme has been saying already, noise filtering and interpolation are actually identical processes. Both involve spatial filtering. This often isn't obvious to the casual reader, but the reality is the signal processing is equivalent. Ray appears to be conflating "interpolation" with "unsharp" and there really isn't justification for that. Yes, the Foveon imager produces very high resolution for its pixel density but that isn't necessarily because of "interpolation". Both Bayer and Foveon images have spatial filtering applied. As has been stated already, an advantage of the Foveon in regards to spatial luminance resolution is the lack of an OLPF.
As far as B&W goes I've wondered the same. I was anxious to try that out with an SD1, but since it looks like no one is actually going to own one I guess I won't. Interesting to note you can get a few Canon models modified to remove the CFA and OLPF for what should be extra sharp B&W images. I've asked more than one place about results with these cameras but have never found someone actually using one!
Final note on the SD1, I was given to understand this imager does in fact do CDS using a different pixel cell than the SD15. Probably the reason for the improved ISO performance.
Ken
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Fred, I'm not sure if Robin Wood was intended, or lost in translation or a typo. But whatever, it's a great line made all the better!
That's my boy Fred! Once you've tasted Jurançon you have that 'otherness' the rest can only envy.
;-)
Rob C
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Look here (http://media.dxomark.com/index.php/Cameras/Camera-Sensor-Database/Sigma/SD1).
Of course, DXO does not test resolution so we will have to look elsewhere for those results.
Regards,
Bill
Hi Bill,
DxO also has similar place holders for three other Sigma cameras, yet no reviews, nor did I find anything on the link you provided mentioning of a future review.
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I used Robin Wood as an image, sort of saying "the one who saves the poors".
I was in Nothingham in my youth, there is really the famous tree. Don't know if it's fake or Robin Wood actually used it or if all that is a legend like the scotish lake's monster (ups...I should not say that, there are scotish photographers around here ;) ). Really loved Nothingham city, very elegant.
Cheers.
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Hi Bill,
DxO also has similar place holders for three other Sigma cameras, yet no reviews, nor did I find anything on the link you provided mentioning of a future review.
Look at the top just above specifications where it says: "This product will be tested and reviewed on July on dxomark.com. Stay tuned by subscribing to our newsletter. " July is almost over, so they might be a bit behind.
Bill
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Fred
Robin Wood sounds so much more poetic than Robin Hood, but either way, that's still one of the best lines I've read ;-)
;D oh dear...I did not see my mistake! Do you know why? it's because in french Robin Hood is Robin des bois , and bois means wood.
Ok, if more poetic I stay with Robin Wood then.
Cheers.
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;D oh dear...I did not see my mistake! Do you know why? it's because in french Robin Hood is Robin des bois , and bois means wood.
Ok, if more poetic I stay with Robin Wood then.Cheers.
Please do; it's far more cool!
I also believe that I have some secret mojo working for me when I speak Spanish here; I can always find what I want if it costs money but it gets strangely difficult when it should be for free. Hmmm....... must be Scottish charm working backwards - a time-zone slip or something similar.
Rob C
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With a Foveon by shooting for black and white, you throw away it's one advantage, it's co-sited colour, but you get it's noise and ISO performance disadvantages.
Spatially, a Foveon used for B&W images (summed color channels) is equivalent to a true monochrome sensor.
Co-sited subpixels (Foveon) means that the need for OLPF is reduced (Sigma leaves it out altogether). This means that an APS-C sensor featuring 15 unique mega sensel locations chould provide high-acutance "B&W" images (somewhat aliased).
A Bayer APS-C sensor with no OLPF of 15 unique mega sensel locations might provide similar acutance for B&W (and better noise/ISO characteristics, lower price etc) but should have more pronounced problems with aliasing (even when used for B&W), and I am unaware of any such sensors available in off-the-shelf cameras.
I think that the situation is complicated by the fact that accurate capture of color is good even for B&W photographers, as it is used for post-processing simulation of color filters for creative effects.
-h
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The need for OLPF is only reduced with respect to to chroma moire, not aliasing in general to which it is as prone as any sampled system. I'd be keen to see how the Foveon performs as a black and white sensor because if you're not decoding colour from it, you're not getting into issues of matrix induced noise. It could work well, unless the extra circuitry in there to get the colour is detrimental to dynamic range.
Given the availability of Bayer CFA sensors with low noise and higher measured resolutions (with lower aliasing) than 15mp, I'd probably go that route myself, use post processing to generate the BW from colour and if I wanted that crunchy aliased look just use a crap downsample filter. I'm sure I'd save myself money that way so I could spend on more good glass.
Graeme
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With a Foveon by shooting for black and white, you throw away it's one advantage, it's co-sited colour, but you get it's noise and ISO performance disadvantages.
Bayer filter CFA could loose upto perhaps 2/3 of light compared to a monochrome sensor. I would assume that Foveon treated as monochrome would also have this light gathering advantage, which should also help with noise in certain situations.
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Well, we know chroma noise is an issue - but if you just look at luma noise (the Foveon papers read of treating their "green" as luma) do you see an advantage over a Bayer CFA?
Graeme
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I'm not worried so much about shot noise as read noise.
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Sorry, i accidently deleted my message to which you replied. I am copying it here again:
Well, we know chroma noise is an issue - but if you just look at luma noise (the Foveon papers read of treating their "green" as luma) do you see an advantage over a Bayer CFA?
Graeme
I think I can see less light collection in green pixels on Bayer CFA treated as luminence vs. monochrome sensor as shown in the image below taken with two exact same sensors except one being Bayer and other mono.
(http://djjoofa.com/data/images/bw_col_both.jpg)
Since the green pixels on Bayer are darker compared to mono pixels the shot noise component should be more in Bayer. If Foveon pixels can be treated as mono pixels in the same way, I would think they should have similarly better shot noise component.
Joofa
I'm not worried so much about shot noise as read noise.
Depends upon the situation. Can't be summarily dismissed, IMHO. Furthermore, if Bayer really looses upto 2/3 of light compared to mono, and we can assume Foveon may be operated as mono easily, then under some low light situations the better light gathering of mono should help in reducing the perceptibilty of read noise.
In addition, a Foveon treated as mono might require less lighting to get equivalent brightness as the above image shows. Again lighting situation or budget can't be summarily dismissed, IMO.
Joofa
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Ray, so it sounds like you like the look of no OLPF. If colour accuracy is not an issue for you, and you generally shoot at low ISO where noise is less of an issue, then great. Other thing you can do is shoot with a higher resolution Bayer CFA camera and downsample it - that can induce the same kind of lack-of-OLPF look you like (depending on choice of downsampling filter), could also lead to still lower noise.
Graeme
Graeme,
I certainly do like the look of any crisp and detailed image with lots of micro-contrast, provided color redition is also pleasing. Don't we all?
I'm very much of the persuasion that a camera is a tool for a specific purpose. I prefer to use a cropped-format DSLR when I want the longest reach with my longest telephoto lens, which is the Canon 100-400/5.6 IS zoom, but I also prefer full-frame when I want the widest FoV.
Sometimes I will choose a camera, such as the Nikon D7000, because of its low noise, low weight, high DR, and HD video capability.
If I already owned a Sigma 800/5.6 lens with Sigma mount, I might be excited at the prospect of fitting to it an 'effective' 30mp cropped format body.
However, I don't own such a lens and don't intend buying one, partly because it doesn't have IS. I wouldn't consider buying the Canon 800/4.5 either, because it's not only heavy but also very expensive; more expensive than the Sigma. In fact, the Sigma 800 with SD1 should be less expensive than the Canon 800/5.6 IS with 7D.
I have no problem if you want to describe noise reduction as a type of interpolation. I was speaking from the layperson's understanding of interpolation as the creation of entirely new values (as opposed to adjusted values), as in upsampling an image which results in the creation of totally new pixels which didn't exist before the upsampling.
In concept, I see a difference between the creation of completely new values for the missing two primaries in the Bayer Array, estimated from the values of surrounding pixels, and the noise reduction applied to existing values of all 3 primaries in the Foveon pixel.
But let's not get hung up on verbal definitions. If the two processes come under the same technical umbrella of interpolation, then so be it.
What intersts me more are the advantages of the SD1 as a tool which may be able to produce results, in certain circumstances, that no other camera can.
What do you predict the comparison would be if I were to remove the AA filter from my 15mp Canon 50D and, using the equivalent quality and FL of lens, compare it with the SD1 at base ISO, ensuring equal FoVs of course?
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Sudhakaran, the problem with Foveon is is not that it samples RGB at the same spatial point, but that to enable it's sampling of RGB at the same point it uses silicon thickness as a colour filter and that leads to poor and noisy colour. With a Bayer CFA you get good colorimetry and lower noise, but you sacrifice the layered arrangement. With Bayer CFA you can always produce a sharper image and the appearance of spatially co-located colour through downsampling. With Foveon there's very little that can be done about the colour.
Graeme
Just curious, but is it possible for a separate circuit be built to read the array like it was a Bayer array and then use that mathematics to further process the RAW signal (or even add to it for more latitude in post processing) from the Foveon photosites?
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Sareesh, once you've read the RAW you can interpret it how you want. That won't help as it's how the Foveon does colour filtering that is the issue with it.
Ray, "I certainly do like the look of any crisp and detailed image with lots of micro-contrast, provided color redition is also pleasing. Don't we all?" - not, we don't all! Crisp and detailed - yes, but not so crisp or so detailed that sharp edges look jaggedy or fine detail descends to noise. I like a very naturalistic image - one that is how I see the world where you're not aware you're viewing pixels. With Foveon images I'm always keenly aware that the image is made up of pixels. I'd take soft (yes, soft, not out of focus, but soft) smooth and creamy over edgy any day.
Yup - same umbrella. The problem here is not you or what you think of as interpretation or not, but the Foveon mantra that is often promulgated by it's proponents that "we don't interpolate". Similarly they'll show the depth diagram of the pixel with bright red, green and blue layers, whereas in the case of a Bayer CFA the dye filters really are bright red, green and blue, but in the Foveon the equivalent colours of the "colour filter" are muddy and muted.
Ray - it's a 5 micron pixel, right? So a 3.9 micron pixel on a Bayer CFA would give the same telephoto reach measured luma resolution? Canon 600D is getting closer at 4.3 micron. DSLRs don't usually drop much below 5 micron for image quality (noise) reasons. Sounds like you'd have to do experiments with how sharp your glass is too, and how steady the camera and subject are as at that distance any movement will eat any rez advantage very quickly.
BTW, I think the "effective 30mp" is a rather exaggerated number. I think Foveon sans-OLPF to a Bayer-CFA with OLPF is about 24mp, but lower luma aliasing on the Bayer due to it using an OLPF. Remove OLPF from both and you'll get equivalent measured resolution around 20mp (harder to guess, especially as I like OLPFs and think they're necessary, not optional) on the Bayer to the 15 on the Foveon. The OLPF takes most of the resolution hit, not the mosaic.
Graeme
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Ray - it's a 5 micron pixel, right? So a 3.9 micron pixel on a Bayer CFA would give the same telephoto reach measured luma resolution? Canon 600D is getting closer at 4.3 micron. DSLRs don't usually drop much below 5 micron for image quality (noise) reasons. Sounds like you'd have to do experiments with how sharp your glass is too, and how steady the camera and subject are as at that distance any movement will eat any rez advantage very quickly.
BTW, I think the "effective 30mp" is a rather exaggerated number. I think Foveon sans-OLPF to a Bayer-CFA with OLPF is about 24mp, but lower luma aliasing on the Bayer due to it using an OLPF. Remove OLPF from both and you'll get equivalent measured resolution around 20mp (harder to guess, especially as I like OLPFs and think they're necessary, not optional) on the Bayer to the 15 on the Foveon. The OLPF takes most of the resolution hit, not the mosaic.
Graeme
Graeme,
I'm well aware of the benefits of good glass and a steady camera. The Foveon sensor has been around for a long time and a number of comparisons have appeared on the internet which suggest the resolution and detail is close to that from Bayer sensor of double the pixel count, perhaps slightly less.
I've frequently seen comparisons betwee MFDBs and DSLRs of similar pixel count. The MFDB has a slight edge, but nothing as great as double the pixel count.
I've also seen comparisons on MaxMax of 5D images before and after the AA filter has been removed. Again, the differences are subtle, and certainly not equivalent to a camera with double the pixel count, with AA filter.
Please explain.
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"number of comparisons have appeared on the internet which suggest the resolution and detail is close to that from Bayer sensor of double the pixel count, perhaps slightly less" - the ones I've seen compare a Foveon based camera to a Bayer CFA with OLPF. They're also comparing aliases from the Foveon as if they were real detail which they're not. Unless you use a proper test chart that shows up aliasing, you're not getting a reasonable answer here.
With MF you're changing a whole bunch of variables - you're using a different lens and sensor size which makes things tricky.
On the 5D don't they just remove half the OLPF - the other half being stuck to the sensor, or is that a different camera I'm thinking of?
I find that with my Bayer CFA (+OLPF) camera systems I can measure limiting resolution of about 78% of the horizontal pixel count. That's like saying you get 60% of the MP count as real measured resolution with low aliasing too. If we assume that half of that loss from 100% is OLPF and half the mosaic pattern (not an unreasonable assumption) that gives a just under 80% of the MP count as real measured resolution figure. Or in other words, to get a measured 15mp resolution that would imply needing to start with 19mp.
The problem is when you eyeball this stuff rather than measure it, you (especially looking at a scene rather than a chart) will see aliasing as real resolution. So when you compare a camera with low aliasing with one with high aliasing, you really do need to measure rather than look. Of course, if you like the look of the aliasing then eyeball away as measurements mean little in that case, but personally, I prefer high measured resolution without excessive aliasing rather than potentially higher resolution that is corrupted by aliases.
As I'd mentioned earlier, photography is a wonderful pursuit as it combines the technical and the creative. In this case, measuring resolution and aliasing will tell you what's going on and will inform you of why you're perceiving the image as it is, but it doesn't dictate your personal imaging aesthetic that obviously differs from mine with regards to aliasing.
Graeme
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The problem is when you eyeball this stuff rather than measure it, you (especially looking at a scene rather than a chart) will see aliasing as real resolution. So when you compare a camera with low aliasing with one with high aliasing, you really do need to measure rather than look. Of course, if you like the look of the aliasing then eyeball away as measurements mean little in that case, but personally, I prefer high measured resolution without excessive aliasing rather than potentially higher resolution that is corrupted by aliases.
As I'd mentioned earlier, photography is a wonderful pursuit as it combines the technical and the creative. In this case, measuring resolution and aliasing will tell you what's going on and will inform you of why you're perceiving the image as it is, but it doesn't dictate your personal imaging aesthetic that obviously differs from mine with regards to aliasing.
Graeme
Graeme,
It sounds to me as though you are ultra-critically tuned to any hint of aliasing when you view an image.
Do you see any aliasing in the image at Dpreview of the old guy snoozing, posted by cinefeel, linked below?
http://forums.dpreview.com/forums/readflat.asp?forum=1027&thread=38932863
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Sure, the hair and eyebrows look a bit "crunchy" - but that shot is not anywhere near as bad as some Sigma images. I find if I add a minute blur to that shot, I find it looks more "natural" and less plasticky to me. I really don't like what the camera does with fields of grasses in landscape shots where instead of naturally blurring out into the distance, you get a descent into noise.
But now we're getting into the aesthetics of imaging. My tech talk here is not about what we like and don't like, but why the image looks the way it does - which is predominantly the lack of optical low-pass filtering. Where it would be interesting to go from here is to add an OLPF to the Sigma and compare with / without, and also to deconvolve the OLPF and compare that to without. Then you'd get a much better idea of exactly what it is you're seeing.
Graeme
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Hi Graeme
I certainly appreciate your explanations and your insights and I also do not buy into some of the rather extreme claims for the Foveon approach. But I also believe that images are best judged by your eyes, not theory when considering aesthetic matters (engineering issues are of course best dealt with more formally).
As far as the resolution claims for Foveon are concerned, you may be technically correct but I can't help feel that your own preferences tend to lead you to over-emphasise the negative aspects of Foveon. I use a SD9, DP1 and SD14, not as my main cameras, but mainly for experimentation with alternative processes. And in my opinion, (even ignoring the hype), the images look pretty good, especially in good light. The colour is attractive and can be made acceptably natural and realistic with DNG profiles. The resolution in prints of the 4.6MP sensor seems to me to be the equal of 12MP class Bayer cams (I have a 5D Mk1, 450D for comparison). As you say, without some form of bandwidth limitation, aliasing must be present, but mostly it doesn't seem to be visible. You see it most often in architectural type subjects and sometimes in grass stems for example that are orientated on a diagonal but Photozoom upsampling methods usually elliminate it.
One of the frustrating things that surrounds the Foveon debate is for people to tend to take a position for or against the tech (Sigma hype partly to blame). I wish people would be more neutral and try to accept that there is something about Foveon images that is attractive and whilst it might never be mainstream, it is a valuable alternative and concentrate on getting the best out of it rather than simply dismissing it (or hyping it)...
Sareesh, once you've read the RAW you can interpret it how you want. That won't help as it's how the Foveon does colour filtering that is the issue with it.
Ray, "I certainly do like the look of any crisp and detailed image with lots of micro-contrast, provided color redition is also pleasing. Don't we all?" - not, we don't all! Crisp and detailed - yes, but not so crisp or so detailed that sharp edges look jaggedy or fine detail descends to noise. I like a very naturalistic image - one that is how I see the world where you're not aware you're viewing pixels. With Foveon images I'm always keenly aware that the image is made up of pixels. I'd take soft (yes, soft, not out of focus, but soft) smooth and creamy over edgy any day.
Yup - same umbrella. The problem here is not you or what you think of as interpretation or not, but the Foveon mantra that is often promulgated by it's proponents that "we don't interpolate". Similarly they'll show the depth diagram of the pixel with bright red, green and blue layers, whereas in the case of a Bayer CFA the dye filters really are bright red, green and blue, but in the Foveon the equivalent colours of the "colour filter" are muddy and muted.
Ray - it's a 5 micron pixel, right? So a 3.9 micron pixel on a Bayer CFA would give the same telephoto reach measured luma resolution? Canon 600D is getting closer at 4.3 micron. DSLRs don't usually drop much below 5 micron for image quality (noise) reasons. Sounds like you'd have to do experiments with how sharp your glass is too, and how steady the camera and subject are as at that distance any movement will eat any rez advantage very quickly.
BTW, I think the "effective 30mp" is a rather exaggerated number. I think Foveon sans-OLPF to a Bayer-CFA with OLPF is about 24mp, but lower luma aliasing on the Bayer due to it using an OLPF. Remove OLPF from both and you'll get equivalent measured resolution around 20mp (harder to guess, especially as I like OLPFs and think they're necessary, not optional) on the Bayer to the 15 on the Foveon. The OLPF takes most of the resolution hit, not the mosaic.
Graeme
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Dave, hard to be neutral when it comes to aesthetics! On the numbers side, I'm trying my best to give the numbers that I've measured and they're repeatable and consistent with other measurements of similar cameras. I wish people would shoot better charts on the Foveon and then I'd have better numbers to go on there - so instead I just give it a 100% luma resolution factor (usually reckon Bayer CFA with OLPF around 78%).
The "for or against" is indeed a polarized reaction, and unfortunate. Without it we'd be able to have much more interesting discussions on the colorimetry and resolution and dynamic range aspects.
Aliasing is most easily visible when you get moire - then it stands out like a sore thumb. When it's present in an image that doesn't have a repetitive line structure it manifests in more subtle forms - crunchy edges, stair-step edges, diminishing detail descending into noise etc., but these are harder effects to observe and are most easily confused with real resolution. I'm sensitive to such effects, and doubly so because I deal with motion imagery where the temporal aspect can make aliasing appear more obvious.
As you mention, stair-stepping can be dealt with by up-samplers that work on an edge-adaptive basis, but similarly the per-pixel softness of a OLPF using camera can be dealt with by de-convolution or downsampling.
What I'm keen for photographers to understand is what measurable aspects of photography correlate with what they see visually. I think that's useful and powerful for them to know so that they can understand why they like what they like and how they can use that to their visual advantage.
Graeme
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Graeme,
I certainly do like the look of any crisp and detailed image with lots of micro-contrast, provided color redition is also pleasing. Don't we all?
...
I dont know what micro-contrast means.
I like crisp images with _real_ detail.
For many organic non-man-made objects, I can live with lots of aliasing, and it can add to the perceived crispness.
For many man-made (or highly structured natural objects), aliasing looks really bad to me, and I know of no bullet-proof limited effort post-processing procedure to fix it.
-h
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I dont know what micro-contrast means.
Have you tried searching the internet for a definition and explanation. ;D
Following is a good explanation relating to the concept of lens contrast, from a tutorial on this site at:
http://www.luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml
When we talk about lens contrast, we're not talking about that quality. What we're talking about is the ability of the lens to differentiate between smaller and smaller details of more and more nearly similar tonal value. This is also referred to as "microcontrast." The better contrast a lens has (and this has nothing to do with the lightdark range or distribution of tones in the final print or slide) means its ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other.
The article also explains how subtle differences in color in adjacent pixels can add or create microcontrast, which may not be apparent if the image were B&W.
Now, I don't pretend to be as technically savvy as many others who contribute to this site, and what I'm about to write may simply be incorrect, or a load of bunkum.
However, when I see an image of a Bayer Array pattern where every pixel is a particular intensity of either red, or blue or green, and it is explained that the demosaicing algorithm has to totally reconstruct two additional values for every single pixel in the RAW image, ie, create completely new values of red and blue for every green pixel, and completely new values of green and red for every blue pixel, and completely new values of green and blue for every red pixel, I'm quite amazed that the final result appears as good as it does, because two thirds of all values comprising the image are total inventions.
Of course, it's understood that such invented, new values are based upon the values of surrounding and adjacent pixels. They are not plucked out of thin air, I know. ;D
I can't help wondering what would happen if one were to photograph a test chart containing just a Bayer Array, ie. millions of red, green and blue squares, setting up the camera so that every red, green and blue square on the test chart were aligned with every red, green and blue pixel on the camera's sensor.
Whether one is 'for' or 'against' the Foveon concept, it seems clear to me there are two major factors contributing to the enhanced effect of detail (or crispness, or crunchiness, however you want to put it).
One factor is its lack of an OLPF, a charcteristic which the SD1 shares with most MFDB backs and a charcteristic which I imagine 'effectively' enhances the 'microcontrast' properties of whatever lens is attached to the camera.
The other factor is the difference in color interpolation methods. In the case of the Foveon, we are at least starting from real values which are spatially accurate even if some intensity is lost or degraded by the absorption qualities of the silicon.
I would guess, (and again I admit I'm not technically knowledeable on the processes), that here we have another source of enhanced microcontrast.
Adding these two factors, or sources of enhanced microcontrast, we get an effect which is significantly greater than we would expect from the omission of just the OLPF.
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However, when I see an image of a Bayer Array pattern ... I'm quite amazed that the final result appears as good as it does, because two thirds of all values comprising the image are total inventions.
The image signal is changing slowly compared to the RGB grid in Bayer CFA; so a lot of it is not invention as the missing values of a certain color are either (more or less) the same as the next pixel of the same color or "shared" by pixels of other colors that are closer. When this condition does not hold as the signal changes more rapidly aliasing happens.
I can't help wondering what would happen if one were to photograph a test chart containing just a Bayer Array, ie. millions of red, green and blue squares, setting up the camera so that every red, green and blue square on the test chart were aligned with every red, green and blue pixel on the camera's sensor.
As noted above Bayer CFA are not designed for this situation as this is not a real world scene. A real world scene has some redundancy (equivalently stated above as varying slowly compared to the RGB grid in Bayer CFA) so that the Bayer scheme suffices.
In the case of the Foveon, we are at least starting from real values which are spatially accurate even if some intensity is lost or degraded by the absorption qualities of the silicon.
In theory Foveon color can be made pretty accurate with the use of certain specialized filtering techniques. If Sigma colors are not accurate enough, then, may be they are not using such techniques, but I'm intrigued and interested in knowing why is that. May be there is a reason of practical implementation versus a theoretical approach.
Joofa
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The image signal is changing slowly compared to the RGB grid in Bayer CFA; so a lot of it is not invention as the missing values of a certain color are either (more or less) the same as the next pixel of the same color or "shared" by pixels of other colors that are closer. When this condition does not hold as the signal changes more rapidly aliasing happens.
This statement is not at all clear to me. Do you mean the camera is moving?
If the camera is moving during the exposure, then I understand the values of red, green and blue as recorded will be different, compared to a perfectly stationary camera, but that doesn't change the situation with regard to the fact that 2/3rd of the total number of values comprising the image have to be invented.
I understand, or at least I'm receptive to the idea, that there are degrees of mathematical probability involved in the demosaicing process.
For example, it may be calculated by the demosaicing algorithm used, that there's a 65% probability that a particular value of blue, in relation to a particular green pixel, is accurate, as calculated from surrounding pixels.
My point would be, in defense of the Foveon process, that there's a 98% chance that the blue pixel is accurate, in the same circumstances, because the blue wavelength is received at the top of the sensel, and maybe an 80% chance, or 70% chance that the red pixel is accurate after appropriate interpolation is made (if that's the right word) after taking silicon absorption charcateristics into consideration.
In theory Foveon color can be made pretty accurate with the use of certain specialized filtering techniques. If Sigma colors are not accurate enough, then, may be they are not using such techniques, but I'm intrigued and interested in knowing why is that. May be there is a reason of practical implementation versus a theoretical approach.
Agreed! Except, of course, it needs to be stated that the Foveon colors are 100% accurate spatially, if not in intensity. (But I sometimes wonder if I'm speaking gobblegook ;D ).
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This statement is not at all clear to me. Do you mean the camera is moving?
I guess he is saying that the light falling onto two neighbor sensels tends to be "similar", just like the weather today tends to be similar to the weather yesterday. How often do you photograph "bayer-like patterns of abrupt on-off transitions perfectly aligned to the pixel grid"?
There are many reasons why they could be similar: camera movement, scene movement, intrinsic properties of light-reflecting objects, diffraction, lense-flaws, etc. The point is that the Bayer sensor seems to still be a good compromise between the virtues that we humans can sense, the way in which light tends to hit a sensor in typical applications, and the process-technology that has been viable to use for the last decades.
-h
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Have you tried searching the internet for a definition and explanation. ;D
Yes, but it seems to be a constructed word with no technical or practical use. Your link made no more sense than other sources I have seen. We might as well succumb to senseless audiophile b.s. like "ethearility", "3-dimensionality", "space", etc. Mumbo-jumbo words invented due to a lack of understanding of how technical aspects affect the subjective impact (which is difficult).
I much prefer writers admiting that they have no idea _why_ a given lense/camera helps them make appealing images, but that it does.
-h
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Agreed.
For many years the concept of resolution seems to have been accepted (the ability to separate two closely spaced points) and so has acutance (the rapidity of the transition between two adjacent tones). Together these terms seem sufficient to describe the subjective impression of detail.
What exactly micro-contrast could mean, I have no real idea. To me it sounds like a synomyn for "fine detail" or "high resolution" or perhaps "acutance". In Foveon land they have also invented the term "fast edge roll-off" also unexplained but sounding remarkably like acutance.
As you note the hifi mags polluted the audio community with a bunch terms that meant nothing but which through continuous repetition became familiar and sounded as though it was conveying something. I have no way of telling whether my subjective impression of "silky highs" and "taut bass" and "air" corresponds with anyone else's (including the author's) but we can sure convince ourselves we are talking about the same thing. Even though my sensitivity to the silkiness of the highs seems to be inordinately influenced by what I ate for lunch. Micro contrast, 3D, verisimiltude seem to be doing a similar job. They tell us nothing meaningful but the allow people with similar brand loyalties to forge a connection that seems emotionally meaningful. It's particularly helpful at seeing off outsiders because if they don't understand the terms it just proves they lack the particular sensitivity that is required to join the elite club...
Yes, but it seems to be a constructed word with no technical or practical use. Your link made no more sense than other sources I have seen. We might as well succumb to senseless audiophile b.s. like "ethearility", "3-dimensionality", "space", etc. Mumbo-jumbo words invented due to a lack of understanding of how technical aspects affect the subjective impact (which is difficult).
I much prefer writers admiting that they have no idea _why_ a given lense/camera helps them make appealing images, but that it does.
-h
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What exactly micro-contrast could mean, I have no real idea.
Really! Well you've certainly come to the right website to be informed, haven't you! ;D
I'll repeat from Michael's definition of microcontrast:
the ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other
Seems quite clear to me. What's the problem? Another way of describing this is to use the word 'sharpness'. There are various ways of increasing the sharpness of an image and different terms to describe such increases in sharpness. Increases in sharpness at the pixel level, with a pixel radius in Photoshop of 1 or 2 or 3 pixels or so, could reasonably be described as an increase in microcontrast.
Increases in sharpness using a pixel radius setting of 20-50 pixels, in Photoshop, could be described as an increase in local contrast.
Increases in sharpness using pixels of significantly greater radius than 50 are usually referred to as increases in global contrast, and are perhaps better done with the brightnesst/contrast control.
What's the problem? Images produced from sensors without an OLPF generally need less sharpening because they have greater microcontrast to begin with.
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Sounds no different from detail to me. What is detail/resolution if not the ability to distinguish one spot of an image from another. No detail = homegenous tone, detail=distinguishable tones. Fine detail=ability to distinguish ever small bits of tone.
Why invent a new term?
Really! Well you've certainly come to the right website to be informed, haven't you! ;D
I'll repeat from Michael's definition of microcontrast:
Seems quite clear to me. What's the problem? Another way of describing this is to use the word 'sharpness'. There are various ways of increasing the sharpness of an image and different terms to describe such increases in sharpness. Increases in sharpness at the pixel level, with a pixel radius in Photoshop of 1 or 2 or 3 pixels or so, could reasonably be described as an increase in microcontrast.
Increases in sharpness using a pixel radius setting of 20-50 pixels, in Photoshop, could be described as an increase in local contrast.
Increases in sharpness using pixels of significantly greater radius than 50 are usually referred to as increases in global contrast, and are perhaps better done with the brightnesst/contrast control.
What's the problem? Images produced from sensors without an OLPF generally need less sharpening because they have greater microcontrast to begin with.
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Sounds no different from detail to me. What is detail/resolution if not the ability to distinguish one spot of an image from another. No detail = homegenous tone, detail=distinguishable tones. Fine detail=ability to distinguish ever small bits of tone.
Why invent a new term?
It's not exactly new. It's been around for a long time. It sort of explains what the sharpening process is trying to achieve.
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A couple of comments.
Resolution and sharpness aren't the same thing. I thought that this was pretty well understood.
When talking about digital sharpness we are in fact discussing edge boundaries... the transitions between tonalities. That's what digital sharpening does – it modifies these boundaries.
One can have a high resolution image that needs sharpening and a low resolution image that doesn't. The factors that affect this are a lens' resolving power, its contrast (MTF) the scene's unique characteristics, the presence or absence of an AA filter, and so forth.
I don't know why anyone had difficulty finding a definition. A Google search turns up an article on this site (http://www.luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml) by Mike Johnston from some years ago as the top hit. It reads in part...
What we're talking about is the ability of the lens to differentiate between smaller and smaller details of more and more nearly similar tonal value. This is also referred to as "microcontrast." The better contrast a lens has (and this has nothing to do with the lightdark range or distribution of tones in the final print or slide) means its ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other
If you've ever used the "Clarity" slider in Lightroom or Camera Raw you are trying to enhance micro-contrast. This is also known as "local contrast enhancement". You can look that up as well.
Finally, as one of the characters in Alice in Wonderland said – "words mean what we want them to mean". The English language has some 1 million words, and is growing by many thousands a year. The reason it's growing is become we need to invent new words to describe things that either didn't esists or didn't need describing before. Now they do.
On a personal note, I think I was the first person to coin the phrase "pixel peeping" some years ago. It doesn't really matter whether I did or not. But the point is that one doesn't need an ISO definition to be created for this to have become an important, even necessary phrase in the digital photography milieu. Everyone now knows what it means. Just as many know what micro-contrast means.
Michael
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Micro-contrast as well as why "resolution" is a poor metric for a lens is covered by Zeiss in this document:
http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_30_MTF_en/$File/CLN_MTF_Kurven_EN.pdf
The basic idea is that micro contrast is related to the steepness of the MTF curve as it approaches the resolution limit. Resolution and micro-contrast are loosely correlated, but not directly correlated. Hence the additional term. As a weak analogy it is sort of like the difference between the MTF50 and MTF10 points.
Like most terms it is overused and misused extensively. Michael has the basics of it right in his his MTF article. Read the Zeiss article linked for a bit more technical description.
Can a camera affect micro-contrast? Yes, most definitely, as the OLPF is not a sharp roll off filter it also attenuates the spatial frequencies associated with micro-contrast. Take the OLPF out and you'll see not just increased resolution (and false resolution corrupted by aliasing) but also increased micro contrast (less susceptible to aliasing as these lower spatial frequencies are further from the Nyquist folding frequency). Some more about how the camera is involved is covered in this second Zeiss article:
http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/$File/CLN_MTF_Kurven_2_en.pdf
NOTE: Appears links don't parse correctly, you'll have to cut and paste
Ken
P.S. Cross posted with Michael, I agree again with what he says for the less technically inclined.
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Sounds no different from detail to me. What is detail/resolution if not the ability to distinguish one spot of an image from another. No detail = homegenous tone, detail=distinguishable tones. Fine detail=ability to distinguish ever small bits of tone.
May I take a guess? Contrast can be determined by an automated process with reference to the information already provided within the pixels, and nothing else. But to determine detail requires a further reference to a standard of what it (human or algorithm) wants to judge (or match) as detail.
In a photograph of a red rose, the algorithm for contrast will perform its task by analyzing the pixels within the file and comparing it to one standard. Even if we shoot a blue shark, it will do the same, referencing the same standard. To put it technically: Contrast detection is a limited system that does not require a feedback loop.
However, the details inherent in the (rose) photograph can only be ascertained (and judged, or matched) by knowing what a rose is, and what it looks like. If we zoom into the rose using an electron microscope, then we will find more detail. Yet this detail has nothing to do with the contrast analysis that has been assigned to the contrast detection algorithm. If we zoom out with a telescope, the details of the rose will be lost due to the limited resolving power of the sensor, yet the contrast algorithm will happily chug along, not knowing what the heck it is comparing. But it does its job well, and leaves the job of finding detail (and selecting the right tools for the job) to the eye of the beholder. Without this great subjective eye, there is no such thing as detail. Sometimes the same eye is content to find details in cells within the rose, or is content with the detail present in just a silhouette of the rose against the sky. This system requires a feedback loop - and the feedback mechanism can only be generated via an ever changing (and sometimes conflicting) library of past experience - both subjective and objective.
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To my mind, "Clarity" or other such sliders enhances large area contrast - it does nothing for small scale contrast. If you look at what the effect is - unsharp mask with a very very large radius and low amount, you can see it's a large area effect. It's enhancing the low frequency MTF, not the highest frequency MTF which traditional use of unsharp mask alters.
What it comes down to is we need an MTF plot rather than talking a single number for resolution. We need to be able to see how much contrast we get for all frequencies represented in the image and also to be able to see how much aliasing occurs and how much that is contributing to the MTF.
http://reduser.net/forum/showthread.php?58227-Leica-Lens-Resolution-test...&p=759177&viewfull=1#post759177 are not exactly MTF plots, but they're related and show pretty clearly what's going on.
Graeme
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What it comes down to is we need an MTF plot rather than talking a single number for resolution. We need to be able to see how much contrast we get for all frequencies represented in the image and also to be able to see how much aliasing occurs and how much that is contributing to the MTF.
Exactly what I am thinking. We seem to be inventing all kinds of indirect, flawed descriptions of the real MTF, some subjective and and some measured ones. Are there any relevant (for this context) moments that are not contained within the MTF?
Reminds me of how to describe a lowpass filter. Do you say "-3dB@10kHz", "12dB/octave Butterworth, fc=100Hz", "a really fat, booming sound", or a detailed sufficient description to capture its behaviour (pole-zero representation, or similar)?
-h
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Not all photographers have the technical background to understand MTF. That's why alternative descriptors are necessary.
I don't care what the PH of a wine is, how much tanin it contains in PPM, or the spectral frequency of its colour under a standard light source. I just want to know how it tastes!! And failing the ability to actually taste it myself, if someone describes it as "ruby coloured, with a rich nose and and a strong finish" I have garnered some information which a chemical assay wouldn't provide.
Michael
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Michael, that's a good argument to provide for a well written description and visuals that elucidate points about images (as you do), but it's not an argument to avoid showing MTF plots. With whisky tasting, flavour graphs are often provided to help explain the taste profile visually, just as an MTF plot shows the contrast profile over frequency visually.
Graeme
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Maybe it depends on which part of the world you were brought up in, which terms are used?
When I learned photography formally, we used a well known starter text by Michael Langford called "Basic Photography". Langford described "sharpness" as the subjective experience of two factors: resolution and acutance. Acutance sounds like what you call micro-contrast; it's edge contrast, the rate of roll off between tones. Our vision responds much more to acutance than resolution, such that a high acutance shot of relatively modest resolution looks subjectively sharper than a high resolution, lower acutance shot - even though the high res shot has more real detail. This property was exploited by film developers like Rodinal which enhanced edge sharpness.
I have no problem with the concept of acutance, my objection is to inventing new terms for old ones or inventing new terms to describe something that doesn't exist. When a new term is coined, it isn't always obvious whether it is a synonym or BS.... ;-)
A couple of comments.
Resolution and sharpness aren't the same thing. I thought that this was pretty well understood.
When talking about digital sharpness we are in fact discussing edge boundaries... the transitions between tonalities. That's what digital sharpening does – it modifies these boundaries.
One can have a high resolution image that needs sharpening and a low resolution image that doesn't. The factors that affect this are a lens' resolving power, its contrast (MTF) the scene's unique characteristics, the presence or absence of an AA filter, and so forth.
I don't know why anyone had difficulty finding a definition. A Google search turns up an article on this site (http://www.luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml) by Mike Johnston from some years ago as the top hit. It reads in part...
What we're talking about is the ability of the lens to differentiate between smaller and smaller details of more and more nearly similar tonal value. This is also referred to as "microcontrast." The better contrast a lens has (and this has nothing to do with the lightdark range or distribution of tones in the final print or slide) means its ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other
If you've ever used the "Clarity" slider in Lightroom or Camera Raw you are trying to enhance micro-contrast. This is also known as "local contrast enhancement". You can look that up as well.
Finally, as one of the characters in Alice in Wonderland said – "words mean what we want them to mean". The English language has some 1 million words, and is growing by many thousands a year. The reason it's growing is become we need to invent new words to describe things that either didn't esists or didn't need describing before. Now they do.
On a personal note, I think I was the first person to coin the phrase "pixel peeping" some years ago. It doesn't really matter whether I did or not. But the point is that one doesn't need an ISO definition to be created for this to have become an important, even necessary phrase in the digital photography milieu. Everyone now knows what it means. Just as many know what micro-contrast means.
Michael
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Isn't this kind of commentary exactly the problem that hifi reviewers invented?
It's all very well to say "Speaker A's high frequencies are more open an airy than Speaker B's" but what does it mean? How can any reader know for sure that their interpretation of what it might mean is what the author intended or what another reader would think? You can't really as there is no common reference point.
What happens is everyone develops their own ideas of what the phrase means, can talk to other people using the same phrase and even appear to have a common language and agree on things - whilst having no idea whether they are talking about the same thing. Intrinsically this kind of undefined casual speech seems to protect itself from scrutiny by being inately vague enough to sound plausible to everyone whilst meaning nothing.
It's interesting to hear people say that micro-contrast as a term has a long heritage. That was unknown to me. Perhaps the term I have always believed to be a common technical term (actutance) isn't? Or perhaps it is in UK only? Geoffrey Crawley the late reviewer and inventor of Paterson developers like Actutol certainly used it in his writings....
Not all photographers have the technical background to understand MTF. That's why alternative descriptors are necessary.
I don't care what the PH of a wine is, how much tanin it contains in PPM, or the spectral frequency of its colour under a standard light source. I just want to know how it tastes!! And failing the ability to actually taste it myself, if someone describes it as "ruby coloured, with a rich nose and and a strong finish" I have garnered some information which a chemical assay wouldn't provide.
Michael
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Accutance is a very good word, and one that photographers in the darkroom days were well familiar with.
But in the digital era it seems to have passed out of favour. Not sure why. Edge contrast, micro contrast, edge sharpening, all are in vogue now and have slightly different meanings. I almost never hear the word accutance anymore except in chemical darkroom discussions.
Tri-X in Rodinal 30:1. Now that had high accutance.
Michael
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Not all photographers have the technical background to understand MTF. That's why alternative descriptors are necessary.
I do respect the difficulties of conveying a complex subjective matter that is so intermingled with technical stuff (incidentally, most of my professional and hobby interests tends to include both domains).
My point is that such alternative descriptors cause more confusion than enlightenment. For the less technically inclined, stating that "this lense enable me to make images that look really good to me, here, have a sample" is (to me) much better than claiming that "this lense have a magical oompti-doomph, and its spaciousness is only rivalled by its 3-dimensionality that really makes your images clarify their statement".
As my example earlier showed, the area of high fidelity has been so infiltrated by meaningless, pretentious words that I cannot have a meaningful discussion with most hifi salespersons or enthusiasts. They reject science, curiousness and humility and have created a quasi-religion. This makes me sad, as I am equally interested in music, music capture and music playback as I am in images.
I don't care what the PH of a wine is, how much tanin it contains in PPM, or the spectral frequency of its colour under a standard light source. I just want to know how it tastes!! And failing the ability to actually taste it myself, if someone describes it as "ruby coloured, with a rich nose and and a strong finish" I have garnered some information which a chemical assay wouldn't provide.
Even though I generally like wine analogies, I am not sure that it is relevant here. MTF can be measured with finite time and resources, and can be understood by finite time and resources. We are talking about simlified measures that contain no information beyond MTF.
Your wine examples, on the other hand, seems to show examples of what is difficult to measure/interpret. Much like "what is a good composition".
-h
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My point is that such alternative descriptors cause more confusion than enlightenment. For the less technically inclined, stating that "this lense enable me to make images that look really good to me, here, have a sample" is (to me) much better than claiming that "this lense have a magical oompti-doomph, and its spaciousness is only rivalled by its 3-dimensionality that really makes your images clarify their statement".
I can't believe you are serious here. You seem to be feigning confusion on the issue.
Surely everyone who knows just a little about photography knows what contrast means. And even the least technical amongst us surely knows that micro means small, or very small.
The meaning of microcontrast should therefore be intuitive. It's also a term that seems particularly appropriate for the digital era. The term acutance implies a sharp edge. It's difficult to imagine how a pixel could have a sharp edge. The smallest degree of detail in a digital image is defined as the pixel. You can't have a representation of detail in a digital image which is smaller than a pixel, and therefore you can't have a pixel with a sharp edge.
But you can have a small cluster of pixels in one image, each differing in RGB values to a greater extent than the pixels of the same size of cluster, representing the same detail, in another image. In this context, it seems appropriate to describe such differences between the two images as differences in microcontrast rather than acutance.
Applying such concepts to the Foveon versus Bayer Array situation, taking as an example a cluster of 4 adjacent pixels, the cluster of 4 in the BayerArray will consist of two green, one red and one blue pixel, ie, a total of just 4 separate values, the other values being interpolated during the demosaicing process.
However, the cluster of 4 pixels on the Foveon sensor, representing the same image detail, will consist of 12 separate values of red, green and blue, each of which has been recorded in reality, at the time the shutter was open.
It would be interesting to compare an image from the Canon 50D after its AA filter had been removed, with the same scene shot with the SD1. Both cameras are 15mp and have a similar size sensor, although the SD1's sensor is very slightly larger I believe.
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I can't believe you are serious here. You seem to be feigning confusion on the issue.
Surely everyone who knows just a little about photography knows what contrast means. And even the least technical amongst us surely knows that micro means small, or very small.
I am not trying to be difficult, but I think that you guys are inventing a vague pseudo-term for something that allready has a better name. How do you measure micro-contrast? What scale differentiates it from global contrast, regional contrast, acutance, sharpness, MTF50? (measured in micrometers or relative to sensor size?). If it cannot be measured, what agreement exists on which images has lots of it, and which have little? Where on the MTF-curve do you see the micro-contrast?
The term acutance implies a sharp edge. It's difficult to imagine how a pixel could have a sharp edge.
The entire system would allow sharp edges to be recorded with some precision in placement and intensity differential. A perfect discrete (sampled) system would only be able to pass frequencies up to (excluding) one half the sampling frequency without aliasing.
Neither a digital camera nor a film camera would record edges with infinite acutance. In my world, that is the system response to a step-function. Or we can measure the system response to an impulse, a frequency sweep or whatever stimuli makes sense.
-h
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I am not trying to be difficult, but I think that you guys are inventing a vague pseudo-term for something that allready has a better name. How do you measure micro-contrast?
With absolutely precise accuracy. One pixel has a value of R=120, G=180, B=240, and the adjacent pixel also has a value of R=120, G=180, B=240. Result? Microcontrast zero between these two pixels.
However, if the adjacent pixel has a value of R=320, G=140, B=89, then we have a specific and clearly defined degree of microcontrast betwee the two pixels. What's your probledm? ;D
I should mention of course, as an afterthought, that the visual perception of such differences in microconstrast, may not correlate with the RGB readings for all individuals. We all have an individulaistic interpretations of color. Some of us are officially color blind, or can't distinguish between reds and greens. Some of us are so mildly color blind that we haven't recognised the problem, or don't see it as a problem.
There many degrees of color blindness in between, for which there is no name.
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There many degrees of color blindness in between, for which there is no name.
I suppose a degree at one end might be called "micro-colorblind?"
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I suppose a degree at one end might be called "micro-colorblind?"
Don't be silly, Eric. ;D
One great advantage of the computer age for the photographer is that one can enlarge any small detail in an image to whatever size one wants.
Here's a random crop of 4 pixels from one of my images. It's been significantly enlarged in Photoshop using nearest neighbour interpolation. It's come up quite well; worthy of any Foveon sensor.
Following is a crop of the same four pixels, but interpolated using bicubic smoother. Oops! No amount of sharpening could fix that.
Now I'm tempted to suggest that the differences between these two versions is conceptually similar to the differences between the Bayer array and the Foveon sensor, but I stress the word conceptually, and I admit I might be drawing a long bow. ;D
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Hi,
To my understanding "the funnel" represents MTF and MTF is shrinking with distance due to target having higher and higher frequency.
The RED goes much further to the right than the Alexa, is this due to higher sensor resolution, different OLP filtering or both? What would the plot look like without OLP?
Best regards
Erik
To my mind, "Clarity" or other such sliders enhances large area contrast - it does nothing for small scale contrast. If you look at what the effect is - unsharp mask with a very very large radius and low amount, you can see it's a large area effect. It's enhancing the low frequency MTF, not the highest frequency MTF which traditional use of unsharp mask alters.
What it comes down to is we need an MTF plot rather than talking a single number for resolution. We need to be able to see how much contrast we get for all frequencies represented in the image and also to be able to see how much aliasing occurs and how much that is contributing to the MTF.
http://reduser.net/forum/showthread.php?58227-Leica-Lens-Resolution-test...&p=759177&viewfull=1#post759177 are not exactly MTF plots, but they're related and show pretty clearly what's going on.
Graeme
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With absolutely precise accuracy. One pixel has a value of R=120, G=180, B=240, and the adjacent pixel also has a value of R=120, G=180, B=240. Result? Microcontrast zero between these two pixels.
However, if the adjacent pixel has a value of R=320, G=140, B=89, then we have a specific and clearly defined degree of microcontrast betwee the two pixels. What's your probledm? ;D
*According to your definition, sensor noise improves micro contrast?
*Many (most?) scenes does not naturally contain infinite contrast transitions. What scenes do you suggest using to estimate the camera "micro contrast" capability?
*Most cameras would (according to your definition) contain millions of micro contrast readings for a single image. How do you propose to manage that data set?
*Are these sRGB pixels? Camera raw pixels?
*Does my former 8megapixel 350D have more microcontrast than my 18 megapixel 7D since it commonly have larger pixel-to-pixel differences?
*It seems to me that your definition of micro-contrast is the same as a discrete 1st-order gradient?
*It seems to me that your definition of micro-contrast is the same as the MTF at the nyquist frequency?
*If you move your camera 1/2 pixel, many cameras will get different micro-contrast using your measure (due to aliasing), especially olpf-less cameras like the Sigmas. Which reading should be chosen?
-h
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Ouch!
It seems that Ray's argument is of the type characterised by Richard Dawkins as "argument from personal incredulity"...
*According to your definition, sensor noise improves micro contrast?
*Many (most?) scenes does not naturally contain infinite contrast transitions. What scenes do you suggest using to estimate the camera "micro contrast" capability?
*Most cameras would (according to your definition) contain millions of micro contrast readings for a single image. How do you propose to manage that data set?
*Are these sRGB pixels? Camera raw pixels?
*Does my former 8megapixel 350D have more microcontrast than my 18 megapixel 7D since it commonly have larger pixel-to-pixel differences?
*It seems to me that your definition of micro-contrast is the same as a discrete 1st-order gradient?
*It seems to me that your definition of micro-contrast is the same as the MTF at the nyquist frequency?
*If you move your camera 1/2 pixel, many cameras will get different micro-contrast using your measure (due to aliasing), especially olpf-less cameras like the Sigmas. Which reading should be chosen?
-h
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Ray, the problem with your model is that you're ignoring noise. Noise will either manifest as thus - fake "micro-contrast" on flat regions that don't have any, or when necessarily noise reduced you'll loose any differentiation in the chroma.
If MTF at sampling limits is micro-contrast then almost by definition it's another description of aliasing.
Erik, plots are on a linear sine zone plate. It's not due to lens - same lens on both and same aperture / focus. It's three things - sensor resolution (5120 across v 2880 across recorded area), OLPF and image processing (demosaic). It's not just that RED goes further to the right, it's the area that is proportional to perceived sharpness, and how the MTF stays higher even at the lower frequencies - ie the MTF50 figure is better both absolute and in proportion to limiting resolution. Without OLPF both resolution and aliasing increase. This is not wise on a motion camera and already we see too much aliasing on the Arri so weakening or removing the OLPF there would be very unwise.
Graeme
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Hi,
I presume that the ultimate solution to achieving maximum resolution with excellent micro contrast is to reduce pixel size to perhaps 3 microns so lens aberrations, diffraction light diffusion in silicon and defocusing will limit MTF to reasonable values at Nyquist?
That would of course reduce DR significantly, about one stop if the image is downsampled to 6 micron pixels?
Best regards
Erik
Ray, the problem with your model is that you're ignoring noise. Noise will either manifest as thus - fake "micro-contrast" on flat regions that don't have any, or when necessarily noise reduced you'll loose any differentiation in the chroma.
If MTF at sampling limits is micro-contrast then almost by definition it's another description of aliasing.
Graeme
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Smaller pixels will get better as the technology improves. The other thing is larger sensors with the same size pixel, and that leads to it's own issues. There's no easy answer other than to keep moving forwards as best as we can!
Graeme
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Ray, the problem with your model is that you're ignoring noise. Noise will either manifest as thus - fake "micro-contrast" on flat regions that don't have any, or when necessarily noise reduced you'll loose any differentiation in the chroma.
Graeme
I never ignore noise Graeme. I'm very sensitive to it. I recall when using my first DSLR, the Canon D60, I was reluctant to use even ISO 400 because noise became clearly apparent. ISO 800 was pretty awful. Even with my latest camera, the Nikon D7000, noise is still apparent at ISO 800, but a vast improvement on the D60 of course.
The reason I might appear to be ignoring the noise characteristics of the SD1 is I simply don't have any reliable information on the subject. DXO Mark have not published their tests yet.
But you are quite right, if noise proves to be an issue at reasonably low ISOs, compared with the latest Bayer type sensors, then that would be another reason not to buy into the system. There has to be a compelling reason for me to buy new equipment. So far, I can think of only one compelling reason why I would even consider getting the SD1, and that is its higher 'effective' resolution compared with existing cropped-format DSLRs.
However, that factor by itself would not necessarily be sufficient reason for me if there are other negative factors such as more noticeable noise at ISO 800 and 1600, compared with Nikon and Canon, and the lack of image stabilisation in certain Sigma lenses, particularly the 800/F5.6.
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Yes Ray, there's an awful lot of factors to take into account! That's what makes this all interesting, and doubly so when Sigma try an alternative path - there are tradeoffs and we've got to know where they are to make a good reasoned decision.
Graeme
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*According to your definition, sensor noise improves micro contrast?
*Many (most?) scenes does not naturally contain infinite contrast transitions. What scenes do you suggest using to estimate the camera "micro contrast" capability?
*Most cameras would (according to your definition) contain millions of micro contrast readings for a single image. How do you propose to manage that data set?
*Are these sRGB pixels? Camera raw pixels?
*Does my former 8megapixel 350D have more microcontrast than my 18 megapixel 7D since it commonly have larger pixel-to-pixel differences?
*It seems to me that your definition of micro-contrast is the same as a discrete 1st-order gradient?
*It seems to me that your definition of micro-contrast is the same as the MTF at the nyquist frequency?
*If you move your camera 1/2 pixel, many cameras will get different micro-contrast using your measure (due to aliasing), especially olpf-less cameras like the Sigmas. Which reading should be chosen?
-h
h,
There are only two instruments I use to test image qualities and charcteristics; my two eyes.
That said, I find it useful to have a set of technical descriptions which tend to closely match, or are consistent with, the impressions I get using my own eyes. It's why I'm impressed with the test results from DXO Mark. They seem consistent with what I see, and I have taken the trouble to make comparative tests of my own cameras to see how they compare with the comparative results at DXO Mark.
To put it another way, if I compare images from two cameras, of the same scene, and the images from one of the cameras look more detailed than the images from the other camera, yet don't appear to have more noise, it may be of only academic interest to be informed that the more detailed images actually do have more noise.
In other words, if the noise is so well disguised that it's not apparent or visible through those two instruments, my eyes, and if the images still appear to be more detailed despite supposedly containing more noise, then I'see no reason to be unduly worried or concerned about the issue.
However, if I were using the camera as a scientific instrument to gather precise data for some research purposes, I would likely be very concerned about the issue of aliasing and the possibility of receiving false data or incorrect data which has resulted from noise or attempts to remove it.
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I feel like we are argueing in a loop here.
h,
There are only two instruments I use to test image qualities and charcteristics; my two eyes.
Does this mean that your eyes return discrete values for r,g and b? Seems to me that two posts ago you suggested a method that was not based on using your eyes at all:
With absolutely precise accuracy. One pixel has a value of R=120, G=180, B=240, and the adjacent pixel also has a value of R=120, G=180, B=240. Result? Microcontrast zero between these two pixels.
However, if the adjacent pixel has a value of R=320, G=140, B=89, then we have a specific and clearly defined degree of microcontrast betwee the two pixels
That said, I find it useful to have a set of technical descriptions which tend to closely match, or are consistent with, the impressions I get using my own eyes. It's why I'm impressed with the test results from DXO Mark. They seem consistent with what I see, and I have taken the trouble to make comparative tests of my own cameras to see how they compare with the comparative results at DXO Mark.
To put it another way, if I compare images from two cameras, of the same scene, and the images from one of the cameras look more detailed than the images from the other camera, yet don't appear to have more noise, it may be of only academic interest to be informed that the more detailed images actually do have more noise.
In other words, if the noise is so well disguised that it's not apparent or visible through those two instruments, my eyes, and if the images still appear to be more detailed despite supposedly containing more noise, then I'see no reason to be unduly worried or concerned about the issue.
However, if I were using the camera as a scientific instrument to gather precise data for some research purposes, I would likely be very concerned about the issue of aliasing and the possibility of receiving false data or incorrect data which has resulted from noise or attempts to remove it.
Using practical, hands-on subjective impressions is all fine and good. After all, that is what guide me and you through 99% of the choices that we face in our everyday life. I am sceptical about coining the term "micro contrast" based only on subjective impressions because you and Michael may not agree what it is, and a 3rd person might have another feeling about what it is. Using the word "contrast" seems to suggest that it has a physical meaning - bound to cause confusion.
If you really only care about subjective impressions, then technical and quasi-technical stuff should be irrelevant to you. So why care about micro-contrast or MTF50 at all? If you, like me, think that great art can be the result of subjective _and_ objective components, then we are back to the original discussion?
-h
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I wish people would shoot better charts on the Foveon and then I'd have better numbers to go on there - so instead I just give it a 100% luma resolution factor (usually reckon Bayer CFA with OLPF around 78%).
I've made available a target for download and print for the seriously interested amongst us at:
http://www.openphotographyforums.com/forums/showthread.php?t=13217 (http://www.openphotographyforums.com/forums/showthread.php?t=13217)
I always hesitate to divert people to other websites (it's not nice to our host), but in this case I wanted to avoid posting the whole story again (hope Michael forgives me). Discussions about those targets, and the results people get, can take place here (again sorry Michael ;) ).
What I'm keen for photographers to understand is what measurable aspects of photography correlate with what they see visually. I think that's useful and powerful for them to know so that they can understand why they like what they like and how they can use that to their visual advantage.
Same with me. There is a difference between looking at the aliasing patterns of almost parallel (hyperbolic) resolution test patterns such as those on DPreview, and targets that test resolution/aliasing at many angles. My target comes closer to looking at a brick wall or road at an angle, and that won't result in an aliasing pattern that mimics the original pattern ...
Cheers,
Bart
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I am not trying to be difficult, but I think that you guys are inventing a vague pseudo-term for something that allready has a better name. How do you measure micro-contrast?
We might take a look at how the ISO resolution determination specifies "limiting resolution". It's the point on the MTF curve where 10% response remains. Apparently that corresponds to human visual resolution limits as well. The only difficulty is that many lens/sensor combinations, even those with OLPFs, have no difficulty in reaching the Nyquist limit with still 10-20% response. Therefore the ISO suggests 10% MTF response or the Nyquist frequency, whichever is reached first, as the limiting resolution.
At those micro detail levels, the contrast reproduction of our capture system is suffering considerable loss, which makes the term Micro-contrast a very apt description of the MTF curve of the capture system falling to a level where human vision also has its limit in resolving capabilities.
Cheers,
Bart
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I'm made available a target for download and print for the seriously interested amongst us at:
http://www.openphotographyforums.com/forums/showthread.php?t=13217 (http://www.openphotographyforums.com/forums/showthread.php?t=13217)
Hi Bart,
Are you familiar with the method of Lionel Baker, called OPW or Optimum Print Width (http://spie.org/documents/Newsroom/Imported/oemMay04/testtalk.pdf), (another description here (http://spie.org/x33663.xml))? He uses a 36 segment "sector star" instead of the sine star. He determines the Optimum Print Width from the blur-circle size, Optimum Print Width being the largest image that can be printed with full detail visible to the eye at arms length. It's a neat way to compare cameras because it avoids the need to up-sample or down-sample to a common print size.
I made a 36 sector sine star (available here (https://sites.google.com/site/cliffpicsmisc/home/o/sinestar36.jpg?attredirects=0), large version here (https://sites.google.com/site/cliffpicsmisc/_/rsrc/1312070203438/home/o/sinestar36_big.jpg)), which can be turned into the "sector star" with Photoshop's Threshhold tool, but I don't think there is much difference in the results between the sine and the sector versions.
Regards,
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Hi Bart,
Are you familiar with the method of Lionel Baker, called OPW or Optimum Print Width (http://spie.org/documents/Newsroom/Imported/oemMay04/testtalk.pdf), (another description here (http://spie.org/x33663.xml))? He uses a 36 segment "sector star" instead of the sine star. He determines the Optimum Print Width from the blur-circle size, Optimum Print Width being the largest image that can be printed with full detail visible to the eye at arms length. It's a neat way to compare cameras because it avoids the need to up-sample or down-sample to a common print size.
Hi Cliff,
Thanks for that link. I wasn't aware of that document, which uses a similar technique. The drawback of a 36 segment star is that it requires a large shooting distance to produce some unresolved detail at a diameter that's large/accurate enough for numerical evaluation. But for visual use, even when it involves a computer display, it could be adequate.
I made a 36 sector sine star (available here (https://sites.google.com/site/cliffpicsmisc/home/o/sinestar36.jpg?attredirects=0), large version here (https://sites.google.com/site/cliffpicsmisc/_/rsrc/1312070203438/home/o/sinestar36_big.jpg)), which can be turned into the "sector star" with Photoshop's Threshhold tool, but I don't think there is much difference in the results between the sine and the sector versions.
It won't make much difference with a dithered print method or when used visually. However, when shooting it with a discrete sampling device, a sine target of sorts is always preferrable to bi-tonal versions. One wants to avoid the presence of higher spatial frequencies (sharp edges) interfering with the spatial frequencies under investigation. That's why I already introduced a 60 cycle sinusoidal version of a Siemens star on Usenet back in 2003, when printers were not as good yet as they are today.
Cheers,
Bart
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I feel like we are argueing in a loop here.Does this mean that your eyes return discrete values for r,g and b? Seems to me that two posts ago you suggested a method that was not based on using your eyes at all:Using practical, hands-on subjective impressions is all fine and good. After all, that is what guide me and you through 99% of the choices that we face in our everyday life. I am sceptical about coining the term "micro contrast" based only on subjective impressions because you and Michael may not agree what it is, and a 3rd person might have another feeling about what it is. Using the word "contrast" seems to suggest that it has a physical meaning - bound to cause confusion.
-h
h,
I think Graeme expressed it very well a few posts ago, as follows:
What I'm keen for photographers to understand is what measurable aspects of photography correlate with what they see visually. I think that's useful and powerful for them to know so that they can understand why they like what they like and how they can use that to their visual advantage.
Now we both know that our eyes alone cannot determine precise values of RGB in a shade without the aid of another tool such as Photoshop.
What's important visually is the detection of differences between shades, and that also applies to many other technical parameters of image characteristics, such as the MTF response of a lens.
If the difference is not great enough for it to be visually significant, then perhaps it doesn't matter from the perspective of the person producing an image.
For example, I might decide to buy a particular lens because it is claimed to have a higher MTF response than another lens at a particular fequency. It is the degree of difference, visually apparent in an image, resulting from the differences in MTF response of different models of lenses, also influenced by other considerations such as price, that helps me make a decision. If the degree of difference is so small visually, whether in absolute terms or because such differences are obscured by other factors, then I hope I would have the sense not to be influenced by such a difference.
If you really only care about subjective impressions, then technical and quasi-technical stuff should be irrelevant to you. So why care about micro-contrast or MTF50 at all? If you, like me, think that great art can be the result of subjective _and_ objective components, then we are back to the original discussion?
I've never written that I only care about subjective impressions. I don't know how you could have drawn that conclusion. I like the term mocrocontrast because it is so apt, so intuitive to understand and so fundamental to the modern digital process of image making. The word contrast is fundamental to all image making, whether photography or painting. No contrast, no picture. A contrastless picture cannot exist. It's an oxymoron, unless you consider a totally uniform area of plain shade, devoid of any detail, a modern work of art perhaps. ;D
When addressing matters of contrast in digital images at the pixel level, or at the level of small groups of pixels, the term micro seems very appropriate to me, and meaningful. The term microcontrast is as precise as it needs to be in communicating a visual effect.
However, we should also be aware that there are certain more global visual phenomena that seem to defy the technical descriptions at the micro level.
I'm no expert in this field, but the following image illustrates very well how the context surrounding an area with a specific and precisely defined RGB value, can create the impression, visually, that the RGB value of another area in a different context has a different RGB value, when in fact it is the same.
It's clear to me that one of those orange circles is a different shade to the other. It's more brown than orange. Not only that; the grey square that contains the brown circle is very noticeably darker than the grey square that contains the paler orange circle.
Now I can't help wondering if there are any viewers who see both orange circles as being the same shade, and see the grey squares that contain each of them as being the same shade, because they actually are the same shade technically.
Both orange circles have the same RGB value, and both squares also have the same RGB values. But please, no need to rush off to see a psychiatrist. ;D
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I think Ray has made it clear that micro-contrast means a variation in the local neighborhood of a pixel. And, that is a valid notion to consider, IMHO. Such analyses are common in signal processing, and I think one can live with the fact that others can have a different name for the same/similar phenomenon that one may have learnt in their domain under a different name or context. The way I see it is that it is important to understand what underlying phenomenon a term such as micro-contrast entails than arguing on name of the phenomenon itself.
Joofa
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Now I know why real photographers have their hair set on fire by some of the nauseating technical discussions that a thread can evolve into. I am a nerd at heart but sometimes its best to get out of the technical arena and let the eyeballs make the call.
Lets just call this "why I continue to inflict the pain using of Sigma cameras"
These were taken during a portrait sitting shared from Smugmug resized to X3 by smuggie to make things "fair". I am sure their are a ton of technical flaws with this demonstration, I am a hobbiest not a camera reviewer.
Exhibit 1
Portrait taken with SD14 and 18-200DCOS lens. Processed with SPP 5 corrected in iPhoto and bumped "definition" whatever that means but I like it.
(http://peterzpicts.smugmug.com/Family/Langdon-2011/i-Mdt2mLR/0/X3/SDIM6456-X3.jpg)
Exhibit 2 Same sitting taken with Nikon D90 and Nikkor 35DX 1.8 Incamera Jpeg, I find it hard to beat Nikon's incamera processing for shots like this.
(http://peterzpicts.smugmug.com/Family/Langdon-2011/i-WWrSrsg/0/X3/DSC4679-X3.jpg)
The bottom line for me I like what I see from Sigma better, and why many others continue to bother with their under engineered equipment.
Paul
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Regarding Paul's examples, my impressions are that the Sigma image is warmer and I think it give the subject more pop, which is more pleasing than the Nikon image. However, I think it would be pretty straightforward to process the Nikon image to match the warmth in the Sigma image.
I really don't see any appreciable difference in detail or sharpness. The eyes are quite sharp and hair strands are nicely defined in both photos.
Subjectively, I don't like the welcome sign in the upper left corner of the Sigma image (can be easily removed w/content aware fill), and I like the smile in the Nikon image much better (maybe she's happier and more relaxed when she saw you using the Nikon ;D).
Both are nice portraits, but I prefer the Nikon for non-technical reasons (good smile). I have trouble seeing any technical advantages that can't be negated with processing.
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The Nikon image simply has a different white balance and brightness. It would take 10 seconds to make it match the Sigma frame if that's what one wanted.
Michael
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I agree with Michael here. There are two broad processes; capturing the image, and processing the image.
Sometimes people find that a particular type of processing using a particular RAW converter produces a more pleasing result, then attribute such pleasing results to the characteristics of the camera.
The other issue, of course, is the necessity of comparing identical scenes using 'effectively' identical camera settings and 'effectively' equal lens quality when trying to examine subtle differences between cameras, if one wishes to be truly objective.
The above comparison images are too small to allow resolution comparisons, but it should also be borne in mind that the SD14 is only 4.6mp (spatially) whereas as the D90 is 12.3mp.
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Resolution will be pretty similar, that particular chip is a pretty good match for most Bayer chips of 10-12MP.
I agree that the differences here are primarily processing. But even if you equalise this, there will be Foveon fans who will claim the Sigma image still looks to have better colour, is more "natural" and "3D". I'm open minded about this, but personally I haven't seen these properties in my own Sigma images yet.
One thing that isn't talked about that much is that Foveon chip has one unique property- it has equal resolution in all colours, while Bayer resolution varies all over the place in different parts of the subject, especially in regions of saturated colour. Mike Chaney (ddisoft) noted this some years ago. It may not happen often but with some subjects (super saturated florals for example), Bayer sensor cameras varying resolution across different areas of subject can create a kind of "out of focus in patches" effect.
I agree with Michael here. There are two broad processes; capturing the image, and processing the image.
Sometimes people find that a particular type of processing using a particular RAW converter produces a more pleasing result, then attribute such pleasing results to the characteristics of the camera.
The other issue, of course, is the necessity of comparing identical scenes using 'effectively' identical camera settings and 'effectively' equal lens quality when trying to examine subtle differences between cameras, if one wishes to be truly objective.
The above comparison images are too small to allow resolution comparisons, but it should also be borne in mind that the SD14 is only 4.6mp (spatially) whereas as the D90 is 12.3mp.
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Resolution will be pretty similar, that particular chip is a pretty good match for most Bayer chips of 10-12MP.
I agree that the differences here are primarily processing. But even if you equalise this, there will be Foveon fans who will claim the Sigma image still looks to have better colour, is more "natural" and "3D". I'm open minded about this, but personally I haven't seen these properties in my own Sigma images yet.
One thing that isn't talked about that much is that Foveon chip has one unique property- it has equal resolution in all colours, while Bayer resolution varies all over the place in different parts of the subject, especially in regions of saturated colour. Mike Chaney (ddisoft) noted this some years ago. It may not happen often but with some subjects (super saturated florals for example), Bayer sensor cameras varying resolution across different areas of subject can create a kind of "out of focus in patches" effect.
I find it strange that there are so few detailed comparisons of such issues on the internet and so few detailed reviews in general of the Sigma Foveon cameras. I recall my impression of the dpreview comparisons of the early Foveon sensors, years ago, which indicated the Foveon sensor was approximately equivalent to a Bayer Array of double the spatial pixel count, but I'm surprised that Dpreview and Imaging Resource haven't even reviewed the SD14, whilst a newer model in the meantime is now available with over 3x the pixel count, which seems to be an unprecedented leap in pixel count for any manufacturer.
Canon progresses more regularly in small increments, from 6mp to 8mp to 10mp to 12mp to 15mp to 18mp. Sigma progresses from 4.6mp to 15mp in one leap, with a price leap to match.
Where are the comparisons with the closest size of camera format and closest effective pixel count, such as the Canon 7D, using really long telephoto lenses of comparable quality?
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Ray,
What DPReview tests is probably related to sales statistics. I have considerable interest in test chart images taken with the Foveon as much data can be measured in those charts. Unfortunately, the sites using good test charts normally test those cameras that sell, and those seem to be OLP-filtered Bayer designs.
Imaging Review tested the Pentax 645D, and that camera was really impressive.
It is quite obvious that Sony will come with two 24 MP APS-C cameras end of August and Nikon is rumored to present new cameras, too. Those cameras will also feature weaker OLP-filters. So the potential advantage of Foevon will be reduced, within a few months. Canon will follow suite for sure.
Sigma makes some impressive lenses like the 500/4.5, 300-800 and 800/5.6. So a Sigma SD1 may be interesting for the long lens shooter, but the same lenses are available on Nikon and Canon, and those systems have more options. You can buy any of those lenses + a D7000 for the price of the Sigma SD1 with money to spare for the D8000 (?).
One additional point is that much of the sharpness advantage of the SD1 is coming from the lack of the OLP filter, much suggesting that the same sharpness can be achieved using better sharpening on the OLP filtered image.
Explanation of the last statement: The Foveon design has a small resolution advantage over the Bayer pattern, perhaps 7% (?). To that comes an OLP-filter needed to avoid aliasing. The Foveon doesn't have OLP filter, which essentiall means that it is aliasing thereby probably producing fake "microcontrast".
The OLP filter does not really reduce resolution but decreases "microcontrast". We can regain much of what has been lost in the OLP filter by sharpening with high amount and low radius and/or using deconvolution methods.
Best regards
Erik
I find it strange that there are so few detailed comparisons of such issues on the internet and so few detailed reviews in general of the Sigma Foveon cameras. I recall my impression of the dpreview comparisons of the early Foveon sensors, years ago, which indicated the Foveon sensor was approximately equivalent to a Bayer Array of double the spatial pixel count, but I'm surprised that Dpreview and Imaging Resource haven't even reviewed the SD14, whilst a newer model in the meantime is now available with over 3x the pixel count, which seems to be an unprecedented leap in pixel count for any manufacturer.
Canon progresses more regularly in small increments, from 6mp to 8mp to 10mp to 12mp to 15mp to 18mp. Sigma progresses from 4.6mp to 15mp in one leap, with a price leap to match.
Where are the comparisons with the closest size of camera format and closest effective pixel count, such as the Canon 7D, using really long telephoto lenses of comparable quality?
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I'm made available a target for download and print for the seriously interested amongst us at:
http://www.openphotographyforums.com/forums/showthread.php?t=13217 (http://www.openphotographyforums.com/forums/showthread.php?t=13217)
I always hesitate to divert people to other websites (it's not nice to our host), but in this case I wanted to avoid posting the whole story again (hope Michael forgives me). Discussions about those targets, and the results people get, can take place here (again sorry Michael ;) ).
Thank you Bart for this wonderful chart.
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Resolution will be pretty similar, that particular chip is a pretty good match for most Bayer chips of 10-12MP.
This of course is only your subjective guesstimate.
I used BartvanderWolf's excellent test chart (link earlier in this thread) to get (very) preliminary results for my Pentax K20D. This is, as said, preliminary, as I could not use a print, so I had to use computer screen instead (from far enough away with wide enough lens). The result was about 0,406 cycles per pixel. Nyquist is of course 0.5, so if we assume that Foveon does it to Nyquist, then Foveon would do 23% better resolution than K20D (per pixel) with Bayer and anti-alias filter, thus a 4.7Mp Foveon sensor would be worth 7.1 Mp K20D sensor pixels (4.7*1.23^2).
(I must admit, that the Foveon AA-less "beyond Nyquist" false detail may also (or may not) look pretty.)
I also did a test with the color chart, and the results unsurprisingly were very similar to above, only very slightly worse. However, the computer screen isn't exactly the best choice for this test, so I'll have to redo it as well, once I get some prints (which won't be soon though, as I don't have an inkjet).
One thing that isn't talked about that much is that Foveon chip has one unique property- it has equal resolution in all colours, while Bayer resolution varies all over the place in different parts of the subject, especially in regions of saturated colour. Mike Chaney (ddisoft) noted this some years ago. It may not happen often but with some subjects (super saturated florals for example), Bayer sensor cameras varying resolution across different areas of subject can create a kind of "out of focus in patches" effect.
Unfortunately it actually does not have equal resolution for all the colors. The top layer provides the most exact positional data, while the bottom one the least. The difference grows with large apertures and near the edges of the sensor and ought to manifest itself the most under low SNR conditions.
In addition this is not overly relevant, as in order for there to be significant resolution loss for Bayer for different colored subjects, the color spectrum would have to be of very narrow band. If one simply looks at the raw data, one'll notice that this is almost never the case, but insted most of the time there is quite a bit of data on all the channels which allows for quite nice demosaicing.
Observations from some years ago should be taken with even larger grain of salt than usually, as the demosaicing algorithms improve constantly. Anyhow, I can imagine that the "oof patch" effect is instead the result of pixel peeping area with detail that is too fine to be resolved and is instead blurred by the AA-filter.
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Thank you Bart for this wonderful chart.
You're welcome. Glad you also like it. It's easy to use and the results are revealing. Try defocusing a tiny bit, and see what happens to resolution. That will reveal how critical accurate focus is for achieving maximum resolution, and how thin the DOF actually is.
Cheers,
Bart
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OK, test charts will provide the exact numbers and therefore the ultimate limits. However, it's my experience that tests often imply bigger differences than you see in practice. For example in DPReview comparisons you often see noticeable differences between cameras in reviews that in practice would not be discernible in prints less than 5 miles wide. Review sites needs to keep providing the impression that camera X is a lot better than camera Y I guess, whilst the reality is the improvement is merely a tiny incremental change.
My practical experience of using the DP1 and SD14 alongside my 450D and 5D is that if there is any practical resolution difference, it doesn't show up in prints made at the maximum size of my R2400 printer. Similarly, the results of the comparison between the SD14 and the Kodak 14nx I published on my website (http://www.whisperingcat.co.uk/scans/sd14vs14nx.htm) showed no discernible difference in 24 x 16 inch prints when eyeballing the prints. Now I admit these field tests are not the same thing as a lab test, but I believe they are a reasonable reflection of what you get in real world photography - which surely is what matters, no?
For what it's worth, DPReview seem to agree with me as they found no extra detail from 12MP m4/3 cameras compared to the DP series Sigmas ( http://www.dpreview.com/reviews/sigmadp2/page17.asp)
ps
Mike Chaney made use of colour test charts in his SD14 vs 5D comparison and demonstrated quite clearly that Foveon resolution is constant for all colours (scoring a constant 1700), whilst the 5D was all over the place (varing between 1630 and 2000) - essentially a variable resolution camera by colour (http://www.ddisoftware.com/sd14-5d/ ). DPreview have some colour chart tests here as well http://www.dpreview.com/reviews/sigmadp1/page20.asp
Whether this translates to field conditions, I don't know.
This of course is only your subjective guesstimate.
I used BartvanderWolf's excellent test chart (link earlier in this thread) to get (very) preliminary results for my Pentax K20D. This is, as said, preliminary, as I could not use a print, so I had to use computer screen instead (from far enough away with wide enough lens). The result was about 0,406 cycles per pixel. Nyquist is of course 0.5, so if we assume that Foveon does it to Nyquist, then Foveon would do 23% better resolution than K20D (per pixel) with Bayer and anti-alias filter, thus a 4.7Mp Foveon sensor would be worth 7.1 Mp K20D sensor pixels (4.7*1.23^2).
(I must admit, that the Foveon AA-less "beyond Nyquist" false detail may also (or may not) look pretty.)
I also did a test with the color chart, and the results unsurprisingly were very similar to above, only very slightly worse. However, the computer screen isn't exactly the best choice for this test, so I'll have to redo it as well, once I get some prints (which won't be soon though, as I don't have an inkjet).
Unfortunately it actually does not have equal resolution for all the colors. The top layer provides the most exact positional data, while the bottom one the least. The difference grows with large apertures and near the edges of the sensor and ought to manifest itself the most under low SNR conditions.
In addition this is not overly relevant, as in order for there to be significant resolution loss for Bayer for different colored subjects, the color spectrum would have to be of very narrow band. If one simply looks at the raw data, one'll notice that this is almost never the case, but insted most of the time there is quite a bit of data on all the channels which allows for quite nice demosaicing.
Observations from some years ago should be taken with even larger grain of salt than usually, as the demosaicing algorithms improve constantly. Anyhow, I can imagine that the "oof patch" effect is instead the result of pixel peeping area with detail that is too fine to be resolved and is instead blurred by the AA-filter.
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I also did a test with the color chart, and the results unsurprisingly were very similar to above, only very slightly worse. However, the computer screen isn't exactly the best choice for this test, so I'll have to redo it as well, once I get some prints (which won't be soon though, as I don't have an inkjet).
It is possible to print it on different printers as well, as long as the PPI is matched to the specific output device. On a Fuji Frontier (300 PPI version) it will just produce a larger target (e.g. the Canon version of the target is 600 PPI, so a print at 300 PPI would result in a 260mm target, and would need to be shot from twice the recommended distance to compensate for the lower resolution).
It's harder than people think to make a Bayer CFA demosaicing fail. It requires a matched Red/Blue color with virtually no difference in luminosity to make it look its worst. Most demosaicing algorithms favor luminance resolution (like human vision), so with even modest response there, it can still do a pretty amazing job.
Cheers,
Bart
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Observations from some years ago should be taken with even larger grain of salt than usually, as the demosaicing algorithms improve constantly. Anyhow, I can imagine that the "oof patch" effect is instead the result of pixel peeping area with detail that is too fine to be resolved and is instead blurred by the AA-filter.
Sorry to bump an old thread. Bayer is indeed well suited for natural image aquisition, and one has to use quite specialized test-patterns to find scenes where full spatial color sampling (e.g. Foveon) really makes a difference.
I think that the (reduced) need for AA-filtering may be the biggest advantage of the Foveon chip.
-h
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Foveon does not reduce the need for an AA filter, it eliminates it. The worst thing you can run up against with the Foveon is stair stepping on sharp lines but this usually gets mushed out when printing or scaling. Although in the case of the SD1 it grinds things up into such smaller pieces than early Foveon sensors so most of the time its being limited by the resolving power of lenses put in front of it.
Only measurebaiters and pixel peepers worry about such minutia, photographers just stand back and watch folks gawk at their work on the wall.
On a related note Sigma has updated their SPP5.0 software to address the color issues. Also the SD1 has a firmware upgrade that corrects several issues with IQ and improves 800+ ISO noise issues. Perhaps Sigma will loan an updated SD1 to Mike and Co. again to judge the progress.
Pete
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Foveon does not reduce the need for an AA filter, it eliminates it.
Not according to Nyquist. According to your taste and practical limitations in the equipment that you have tested, it may have eliminated it.
-h
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And not according to Foveon themselves if you read their own papers on the subject.
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Foveon does not reduce the need for an AA filter, it eliminates it. The worst thing you can run up against with the Foveon is stair stepping on sharp lines but this usually gets mushed out when printing or scaling. Although in the case of the SD1 it grinds things up into such smaller pieces than early Foveon sensors so most of the time its being limited by the resolving power of lenses put in front of it.
Only measurebaiters and pixel peepers worry about such minutia, photographers just stand back and watch folks gawk at their work on the wall.
On a related note Sigma has updated their SPP5.0 software to address the color issues. Also the SD1 has a firmware upgrade that corrects several issues with IQ and improves 800+ ISO noise issues. Perhaps Sigma will loan an updated SD1 to Mike and Co. again to judge the progress.
Pete
I disagree. The jaggies I see in wires and similar stuff in large prints will not just be "mushed out" in photos from the new SD1. It does not even have twice the horizontal resolution of the previous cameras! Yes, it is much higher resolution, but if you previously were not completely happy with 20x30 prints from your SD14 or SD15, you will probably not be completely happy with 40x60 prints from the SD1. Jaggies WILL be visible, and people inspecting the print will realize you either printed the image from a low resolution digital file, scanned it at low resolution, or shot it with a digital camera. "Jaggies" do not show up in scans from a 4x5 camera, if the scan is done right. Lens resolution limits do not show up in the form of "jaggies" - unlike the resolution limits of Foveon sensor cameras. I've heard that files from the Canon EOS 5 D Mk II resize better than those from Sigma cameras. I would like to see an analysis of that. I have also read about landscape photographers who use 39 megapixel (and higher resolution) medium format digital cameras, because they want the best image quality they can get for their huge prints. I frankly do not have the budget to buy one, and I want the versatility of a lens system like Nikon, Canon, Sony, and Sigma provide. I plan to get a Sigma SD1, because it is KING now. While I save up my money, Canon may announce a replacement for the 5 D Mk II. If it is 32 or 36 megapixels, it will be a very hard choice to make, because there will still be advantages to the Sigma with its APS-C size sensor. Shots of birds made at 300mm will give me more detail and maybe not have to be cropped. The weight and cost of high quality, shorter focal length lenses is an advantage (more carryable and cheaper). Of course, the Canon will have live view and video capabilities (no doubt), and that is of interest to me, so there is an advantage of the Canon, as is the expected price. Still, it is image quality that will be making me buy a new camera, not video capabilities.
As for the person who wrote, "I still don't see the reason for all the excitement about Foveon, or even why people see so much "potential" in it. What, exactly, would it do better that what we have? What *could* it do better?" - I bought a Sigma SD14 to "test" the Foveon sensor. I am convinced that it shoots better quality images than any APS-C camera of its era. Today I have a Canon T1i, and while the T1i does best the SD14, it only barely wins, and that makes me think the 14 megapixel claim is close to reality (especially when shooting red objects). BTW, there are a number of 16 megapixel APS-C sensor cameras on the market today. Compare closely, and you will see that image quality varies widely. Some are better at resolving red than others. I believe the Sigma SD1 blows them all away, and it seems to easily best every other "standard" style (non-medium format) DSLR on the market. It is my opinion, based on what I've seen in my SD14 images, that the SD1 will not be bested until we see cameras that are much higher resolution than 30 megapixels. If the Canon 5 D Mk II replacement is 36 megapixels I will likely buy that camera instead, but probably not if it is only 32 megapixels . . . but I will have to see what sort of noise it produces at ISO 100, because one of the main advantages of the Foveon sensor is its very low ISO 100 noise levels. The photos look SO milky smooth, while capturing incredible detail. I LOVE that about the Foveon sensor cameras.
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Honestly I would prefer to not have the AA filter ever, it destroys pixel level sharpness. As far as cleaning up pixelation for super big prints, I would rather fix that in post than try to bring back sharpness, it is easier to destroy than recreate unless you are God.
I also own a D90 and it is nice but I just can't recreate the "presence" of the 4.7MP Foveon shots. Casual observers can see it but cannot quantify why it looks better to them.
Resolution wise the SD1 is a step too far for most purposes and creates a lot of overhead with huge file sizes and exposing every flaw in the lenses put in front of it.
Personally I would like to see a APS version with 2x 1080P horizontal resolution. This would weigh in at 9.7MP. This would open up the option of 2x2 pixel binning feature to produce some really sharp DSLR video. Plus this could allow better filling of diodes with light to improve high ISO operations.
Pete
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Honestly I would prefer to not have the AA filter ever, it destroys pixel level sharpness. As far as cleaning up pixelation for super big prints, I would rather fix that in post than try to bring back sharpness, it is easier to destroy than recreate unless you are God.
Actually, some sharpness can be brought back relatively easily if you have a noise-free image in the first place, and you know (or are able to guesstimate) the blurring function. Blurring is a global function that merely reduce the level of the desired signal.
Moire/Aliasing artifacts can be really hard or impossible to fix. For stair-stepped edges you might be able to do something manually at pixel level, but if you are snapping people in a wedding with pin-stripe suits, or fabrics for a catalog, the task quickly gets very hard and/or time-consuming. Aliasing means that frequencies are falsely recorded, and you/some algorithm would have to _guess_ if it is false or real to remove it.
As sensor density increases, per-pixel blurring will move further and further into spatial frequencies where it cannot be seen unless the image is printed really large and the viewer is standing really close, or cropped really hard. Aliasing/moire, on the other hand, can negatively affect lower frequencies no matter if the camera system is capable of 100MP or 1000MP.
-h