Pages: 1 ... 3 4 [5] 6 7 8   Go Down

Author Topic: What chance has Sigma's SD1?  (Read 50756 times)

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: What chance has Sigma's SD1?
« Reply #80 on: May 25, 2011, 02:07:43 pm »

There are a number of issues with your post, but I'll just address that last. The Foveon gains no advantage as a B/W sensor. Used that way, it's just a medium resolution 15 MP sensor.
Well, it does not have an AA filter like pretty much all Bayer sensors. Most B&W users would consider that an improvement. Further, demosaicing algorithms may sacrifice some luminance acuity in order to reduce chances of color artifacts. Foveon avoids this.

-h
Logged

Christoph C. Feldhaim

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2509
  • There is no rule! No - wait ...
Re: What chance has Sigma's SD1?
« Reply #81 on: May 25, 2011, 02:10:40 pm »

True, but then any raw file format performs lousy compared to in-camera jpeg if image quality per byte is important.

The reason why we use raw is that it gets us a little more quality and flexibility, at a large filesize cost. Since storage and bandwidth is cheap compared to the number of images and frames per second that most of us need, this tradeoff makes sense.

By this logic, a Foveon sensor that actually gave significant improvements in image quality could still be worthwhile even if it resulted in 3x the filesize.

-h

Exactly.
And that is, what I believe is not delivered for standard situations.
If you want maximum quality on a minimum size sensor that might be a different story.
But for normal photographic application I don't believe the three times bigger files are justified for the gain in sharpness, together with the reported color problems.
I'd prefer to have more "untrue" Bayer-pixels, than 3 times less "true" Foveon pixels.
« Last Edit: May 25, 2011, 02:13:32 pm by Christoph C. Feldhaim »
Logged

melgross

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 56
Re: What chance has Sigma's SD1?
« Reply #82 on: May 25, 2011, 04:03:36 pm »

and what are yours ? because so far it is opinions only

Do you want me to list the entire procedure? I will give you a quick idea of how I tested cameras that manufacturers used to give me to check out.

We had a room for the purpose of these tests. In the room was a heavy rolling camera stand on tracks, similar to our 8 x 10 Durst mural printer. This ensured that the camera was always parallel in the horizontal AND the vertical directions. Lighting supplied by four 1200 WS strobes with 36" soft boxes. Various targets were used, depending on the nature of the test. Both color and resolution tests were performed.

As a lot of this is lens dependent, the choice of lenses is important. Aproblem is that not all manufacturers have an exact equivalent of another manufacturer, or, if they do, the quality may not be the same. So that involves testing the lenses as well for sharpness, distortion, color, off centered elements, lack of parallelism to and from the camera body, etc.

We didn't do MTF or other testing of that type, because the photographic quality is more important to me than the numbers themselves.

When printing, a 44" Epson was used for various print sizes. Though we didn't always print a full 44" print. Usually once we went to 20 x 30, we would print out portions of the image at greater magnification. It's rarely needed to print to this size for D-SLR's because of the resolution of those cameras. But for medium format, it's different. I've been beta testing Leaf backs since they first came out, and the latter models surely can print up to that size. I'm astounded as to what a difference 80MP can make in a print, even a smaller one.

That's the essentials. As usual, life is more complex, and so were the tests very often, especially if we found what looked to be an anomaly.

But testing did include taking actual photo's with the cameras, both in our studio, and out in the "real"world".
Logged

deejjjaaaa

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1170
Re: What chance has Sigma's SD1?
« Reply #83 on: May 25, 2011, 04:07:42 pm »

Do you want me to list the entire procedure? I will give you a quick idea of how I tested cameras that manufacturers used to give me to check out.

We had a room for the purpose of these tests. In the room was a heavy rolling camera stand on tracks, similar to our 8 x 10 Durst mural printer. This ensured that the camera was always parallel in the horizontal AND the vertical directions. Lighting supplied by four 1200 WS strobes with 36" soft boxes. Various targets were used, depending on the nature of the test. Both color and resolution tests were performed.

As a lot of this is lens dependent, the choice of lenses is important. Aproblem is that not all manufacturers have an exact equivalent of another manufacturer, or, if they do, the quality may not be the same. So that involves testing the lenses as well for sharpness, distortion, color, off centered elements, lack of parallelism to and from the camera body, etc.

We didn't do MTF or other testing of that type, because the photographic quality is more important to me than the numbers themselves.

When printing, a 44" Epson was used for various print sizes. Though we didn't always print a full 44" print. Usually once we went to 20 x 30, we would print out portions of the image at greater magnification. It's rarely needed to print to this size for D-SLR's because of the resolution of those cameras. But for medium format, it's different. I've been beta testing Leaf backs since they first came out, and the latter models surely can print up to that size. I'm astounded as to what a difference 80MP can make in a print, even a smaller one.

That's the essentials. As usual, life is more complex, and so were the tests very often, especially if we found what looked to be an anomaly.

But testing did include taking actual photo's with the cameras, both in our studio, and out in the "real"world".

I see... "We didn't do MTF or other testing of that type"... so that is just your visual impressions... somebody here was able to see the infamous "6 stops" more DR... did you see it too ?
Logged

melgross

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 56
Re: What chance has Sigma's SD1?
« Reply #84 on: May 25, 2011, 04:19:39 pm »

Well, it does not have an AA filter like pretty much all Bayer sensors. Most B&W users would consider that an improvement. Further, demosaicing algorithms may sacrifice some luminance acuity in order to reduce chances of color artifacts. Foveon avoids this.

-h
It has to be remembered that 15MP is the province of under $1,000 cameras today, and that cameras costing just a fraction of this one are already at 24MP, and will likely go higher late this year, or early next. The antialising filters used are getting weaker with every model of higher resolution camera that comes out. The $10,000 Pentax 40MP model doesn't use one, and neither does the 18MP Leica.

The truth is that Foveon camera have moire as well. They don't have the easy to get rid of color moire, but they are subject to luminance moire, as every other digital camera is. The higher the resolution the camera, the less the moire problem is. I found it to be almost impossible to get a moire, even with a bridal gown and veil, usually a major cause, along with men's suites and jackets, with the new Leaf 80MP back.

I've a feeling that as D-SLR resolution goes higher, we will see even weaker filters, and eventually, none.
Logged

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: What chance has Sigma's SD1?
« Reply #85 on: May 25, 2011, 04:24:22 pm »

Exactly.
And that is, what I believe is not delivered for standard situations.
If you want maximum quality on a minimum size sensor that might be a different story.
But for normal photographic application I don't believe the three times bigger files are justified for the gain in sharpness, together with the reported color problems.
I'd prefer to have more "untrue" Bayer-pixels, than 3 times less "true" Foveon pixels.
Yes, I am sceptical about the quality.

If one wants the best possible quality for a given sensor size (for cost, size, weight, compability reasons), then perhaps Foveon or something Foveon-like will be the answer sometime in the future, as all photons can in principle be counted (unlike Bayer that must discard 1/2 or 2/3 or something)

For most of us it is more about the best quality per dollar, or the best quality within a system that we are already heavily invested in, or a trade-off between IQ, ergonomy, features, etc.

-h
Logged

melgross

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 56
Re: What chance has Sigma's SD1?
« Reply #86 on: May 25, 2011, 04:29:06 pm »

I see... "We didn't do MTF or other testing of that type"... so that is just your visual impressions... somebody here was able to see the infamous "6 stops" more DR... did you see it too ?

MTF tests are much more used for the testing of lenses, not camera bodies. One of the biggest problems in testing bodies are the faults of the lenses themselves. But when testing bodies, I didn't see a purpose in testing for lens defects. Michael and a number of other professionals who have sites such as this one are not enamored of doing technical tests such as MTF tests. They would rather take the camera and use it. I agree to a great extent. There's nothing like taking actual pictures.

You can demean the idea of looking at pictures, and so demean everything Micheal does here when he evaluates cameras and lenses. That's not helpful. Nor is it meaningful.  We shot tests in our lab that were repeatable, and would tell us all we needed to know about the items under test. This was carefully done, and repeatable, and used targets that were built up for that purpose.

And exactly what did you do?
Logged

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: What chance has Sigma's SD1?
« Reply #87 on: May 25, 2011, 04:32:34 pm »

It has to be remembered that 15MP is the province of under $1,000 cameras today, and that cameras costing just a fraction of this one are already at 24MP, and will likely go higher late this year, or early next. The antialising filters used are getting weaker with every model of higher resolution camera that comes out. The $10,000 Pentax 40MP model doesn't use one, and neither does the 18MP Leica.
I might have misinterpreted you, but your post gave me the impression that you thought that a 15 megapixel Foveon sensor would perform like a 15 megapixel Bayer camera when shooting b&w. I believe that an AA-filter less 15 mp Foveon performs like an a*15 mp sensor Bayer when shooting B&W. "a" is some manufacturer/model-dependent scaling factor >1.


Quote
The truth is that Foveon camera have moire as well.
Of course. Nyquist tells us that all digital cameras will need AA-filters that are shaped like sin(x)/x of infinite extent to remove all aliasing in the general case while having maximal passbandwidth.

Luckily we can usually settle for "looks good to me".

-h
Logged

Dave Millier

  • Full Member
  • ***
  • Offline Offline
  • Posts: 146
    • Whispering Cat Photography
Re: What chance has Sigma's SD1?
« Reply #88 on: May 25, 2011, 04:39:27 pm »

Interesting way you have of inverting the colour resolution issue  :)  Foveon sensors have stable resolution across all colours, Bayer CFA sensors have variable resolution across colours. You can see this quite clearly in Mike Chaney's (ddiSoft, makers of Qimage) comparison with his 5D using colour resolution charts. It is the 5D that struggles to match the SD14 resolution. Admittedly this is a worse case, using the kind of highly saturated near primary colours of the flowers he uses but it makes the point, even if it is rare to hit that exact situation.

Personally, I wouldn't go down the route of criticising the Foveon colour resolution, I'd focus more on its tendency to show yellow/green casts that are awkward to dial out, occasional problems with bright reds and some units seem to suffer "Italian flag" green edges.


I've had a fair amount of experience with Foveon sensor cameras. The first thing I can say is that sharpness is not equal to double a Bayer sensor camera. That is, unlike what Michael expects, this camera will not have the equivalent of 30 MP. It will be closer to 24 MP. Now, that's pretty good. But Sony and Nikon already have cameras out with that resolution. Later this year, Canon will up that, and it's possible that Sony and Nikon will as well.

But I've found a big problem with Foveon sensors. That is, they have poor color purity. Unlike Beyer sensors that rely on filters, the Foveon relies on the selective absorbson of light that silicon exhibits as the light passes through the chip. That is, as the light passes further through, different colors are absorbed, allowing each color sensor to reside behind the one in front. This is what makes the Foveon possible. But, that absorbson isn't perfect, hence, colors poison the other layer sensors, resulting in color mixing that simply can't be fixed.

In addition, the sharpness is higher in some colors, but lower in others, when comparing to Bayer sensors. While Foveon sensors have a higher resolution in the red and blue, it's actually lower in the green, again, when compared to Bayer sensors. That's entirely because Bayer sensors have two green sensing sites to one of each red and green, while Foveon sensors have equal sites for all colors. We are most sensitive to green, specifically a green-yellow. So, in practice, the sharpness advantage of Foveon sensors is highly dependent on the subject matter. Sometimes it appears a lot sharper, and sometimes less so.

When I first read about this camera, I thought that Sigma was making a pro model, in the way we think of pro models, and so even though the price was crazily high, I though it MIGHT be worth it for some. But upon finding that it's just a mid range advanced amateur body, I'm rather shocked. While their high end lenses are good, the rest are just what they seem to be. Unless they up their QC by a good bit, this entire senario is doomed, even if they lower the price.
Logged
My website and photo galleries: http://w

Dave Millier

  • Full Member
  • ***
  • Offline Offline
  • Posts: 146
    • Whispering Cat Photography
Re: What chance has Sigma's SD1?
« Reply #89 on: May 25, 2011, 04:54:27 pm »

"Well-known" is a relative term in this case. What I mean is "well-known" amongst people interested in reading and writing about Foveon technology in the sense that it gets referenced/quoted quite often in such discussions.  Here's a link:  http://www.whisperingcat.co.uk/scans/sd14vs14nx.htm

If you have the energy to read it, you'll notice that it is a little different than a lot of reviews/comparisons because it was done using actual prints rather than pixel peeping onscreen. No test methodology is perfect, especially a field test like this one but we did our best to make it meaningful by verifying with our own eyes what the scans show. And I stick by our conclusions even today:  in the context of prints up to 24 x 16 inches, there is no practical resolution difference between the Sd14 and the Kodak 14nx.  Dpreviews tests of the DP series compacts that use the same sensor also agree that there is no detail advantage to 12MP Bayers over the 4.6MP Foveon.  So, I'm happy with the rough rule of thumb that Foveon resolves approximately the same as a Bayer sensor of twice the pixel count.

Despite the above comments, I'm still unconvinced of the merits of the Sigma cameras. They seem to be still too prototype-y for my taste. I had hope that the Sd1 might be the breakthrough product that would take Foveon mainstream but alas it is not to be so. Maybe next time.


While I haven't read your "well known" article (or for that matter, heard it it), my experience is that it never exhibits twice the resolution of a bayer sensor. I don't know your testing methods, but I ran a fair sized commercial photo lab for a long time, and with my equipment, I ran more than a few tests, and prints. My evaluation of Foveon sensor cameras was "meh!".

I'd like this one to be much better, even though the price is a joke.
Logged
My website and photo galleries: http://w

LKaven

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1060
Re: What chance has Sigma's SD1?
« Reply #90 on: May 25, 2011, 08:03:18 pm »

Hmm.  In the study you linked to, the Kodak 14nx looks much better to me.  It doesn't seem that close.

Dave Millier

  • Full Member
  • ***
  • Offline Offline
  • Posts: 146
    • Whispering Cat Photography
Re: What chance has Sigma's SD1?
« Reply #91 on: May 26, 2011, 07:02:14 am »

Interesting. When I lay the 24 inch prints out on the floor, I have no idea which is which. They look absolutely identical to me and as they were supplied unmarked I don't know which is which.

In all the time that article has been up, I have invited people to identify the unmarked samples - to date no one has done it.
Logged
My website and photo galleries: http://w

Bart_van_der_Wolf

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 8893
Re: What chance has Sigma's SD1?
« Reply #92 on: May 26, 2011, 08:54:47 am »

Interesting. When I lay the 24 inch prints out on the floor, I have no idea which is which. They look absolutely identical to me and as they were supplied unmarked I don't know which is which.

In all the time that article has been up, I have invited people to identify the unmarked samples - to date no one has done it.

Hi Dave,

A quick glance suggests an inverted order compared to the smaller prints, unless each pair is in different orders, I'd then have to look at each pair individually and score them per pair. The difference is not huge though. I also see the differences in the smaller prints.

Cheers,
Bart
Logged
== If you do what you did, you'll get what you got. ==

Plekto

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 551
Re: What chance has Sigma's SD1?
« Reply #93 on: May 26, 2011, 12:07:02 pm »

Interesting way you have of inverting the colour resolution issue  Smiley  Foveon sensors have stable resolution across all colours, Bayer CFA sensors have variable resolution across colours. You can see this quite clearly in Mike Chaney's (ddiSoft, makers of Qimage) comparison with his 5D using colour resolution charts. It is the 5D that struggles to match the SD14 resolution. Admittedly this is a worse case, using the kind of highly saturated near primary colours of the flowers he uses but it makes the point, even if it is rare to hit that exact situation.

Ah.  You beat me to it. :)

Sigma's marketing idiocy aside, the sensor has a true 14 million pixels.   This is like on your monitor - a pixel is a full-color range location.  Same as film if you are scanning it.   The problem is compounded by the fact that Bayer pattern sensors, which are sub-pixels are being marketed as the real thing.  So we end up with marketing claims that are as clear as mud for the most part.

The only real advantage of the Sigma is that the color channels have identical resolution.  This produces very good and realistic colors and a very film-like shoulder as well. There also are no real issues with moire from the color, since there is no real "pattern" for the camera or software to interpolate.  So it takes very very good scenery shots.

But it has a fatal flaw in it, like film, because it works like film does.  It shoots at one ISO only.  Anything other than the base ISO is a bunch of computer trickery.  So it is pathetic if you push it more than a stop or two, just like film.   Given that the "base" ISO seems to be about 50-100 on it, it's exactly like throwing some Velvia in your camera and trying to use it for absolutely everything.  Slow shots will look stunning.  Action and low light... yeah... not going to happen.

So it's really the world's best scenery DSLR camera.  And for that, if it were priced at a reasonable $2000 or so, it would be a tremendous tool for people who do that sort of thing.  (such as myself) But at that price?  Not going to touch it.

Me?  I'm a bigger fan lately of the Fuji sensors.  They are inexpensive and their pixel binning and diagonal pattern combined with their HDR mode that brackets and blends inside the camera essentially gives you the cost advantages of a cheap Bayer sensor but pretty much none of the problems. (especially of note is the way it doesn't completely wash out over-exposed areas) The pictures it takes are *this* close to the Sigma.  But the price, well, Fuji's putting that top-end EXR sensor in under $500 cameras.  

Given Sigma's so-so glass, the sad thing is that the Fuji HS20EXR has a similar cropped sensor but a very nice lens - and will probably work 80-90% as well as the Sigma SD1 in terms of output and 200% better in terms of action and low light shots.  Even without interchangeable lenses.  For $500.

Verdict: Love the Sigma.  Will buy the Fuji instead.  Doubly so if Fuji ever releases a DSLR version of that thing.

EDIT - before everybody jumps all over me, let's do a little "napkin" math:
- The Sigma sensor is being calculated to come in at about 30MP equivalent.   Or about 25% better than a 24MP DSLR.  

- If you calculate out the geometry and interpolation losses in a Bayer sensor, and then factor in the AA filter, you end up with roughly a 0.65-0.7x multiplier for most DSLRs in each dimension.   This gives you a rough idea of how many actual full-color locations you can expect.  This allows for easier comparison between technology types.

- The Sony 24MP DSLR comes in at about 11 million actual pixels.  The Sigma has 14 million.  Or about the same 25% difference.
- The Fuji at 16MP has a closer to 0.8X multiplier (give or take) and comes in at about 11MP as well.  (scanned 35mm film is closer to 3-4MP, btw)
- The Sigma has a bit over 14MP and a 1.0x multiplier. 

What this means is that the cameras are all about the same other than that 25% bigger picture/resolution for the Sigma.  But I think Sigma's glass is 25% *worse* than the competition, making it a wash versus the three technologies. Ouch. (actually the math hurts Sigma more, as worse glass has a myriad of other issues with it in terms of image quality aside from absolute resolution)

$500 bridge camera does almost exactly as well as Sigma's new toy.  Man, that's got to hurt...   ;D
« Last Edit: May 26, 2011, 12:50:06 pm by Plekto »
Logged

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: What chance has Sigma's SD1?
« Reply #94 on: May 26, 2011, 01:45:14 pm »

The only real advantage of the Sigma is that the color channels have identical resolution.  This produces very good and realistic colors ...
If by good and realistic colors you mean that the technology is well suited to recreate perceptually the color "as seen", then I think that you are very wrong. I have seen suggested that the reason why earlier Sigma cameras did not have in-camera JPEG was because the lousy color properties of the Foveon sensor meant that they could not do the heavy processing inside a camera with limited processing capabilities.
http://forums.dpreview.com/forums/read.asp?forum=1000&message=38502539&q=fossum&qf=m
Quote from: Eric Fossum
The Foveon sensor, contrary to kool-aid purveyors, does not measure RGB information. It measures the photons absorbed in three different layers of silicon. Only in cartoon-land do the three layers correspond to R,G and B. In fact, R, G and B is invented MORE for a Foveon sensor than R,G, B interpolation for a Bayer sensor, at least in my book. Besides the immense amount of processing required to generate a semblance of R,G and B for the Foveon pixel, the noise floor on the pixel is quite high due to not being able to do correlated double sampling with complete charge transfer. Not as important under bright light conditions, but ugly under low light.
http://forums.dpreview.com/forums/readflat.asp?forum=1027&message=36397198&changemode=1
Quote from: Joseph S Wisniewski
This paper from Richard Lyon at Foveon explains some of that.
http://www.foveon.com/files/CIC10_Lyon_Hubel_FINAL.pdf
...
But the big problem with that chart is that it's plotted all pretty in red, green, and blue, and the Foveon outputs aren't really red, green, and blue. Look at the spectral sensitivity curves, figure 7. There's actually wavelengths where a photon can show up equally in the top, middle, or bottom layers of the sensor. So. light of that wavelenght isn't interpreted as a color, it's interpreted as "white". One stimulus that can produce outputs in all the channels is "bad" from a signal processing standpoint. That's called "mutual information", and you have to uncouple the mutual parts and extract the "separable" information before anything makes sense.
 
If you actually look at the outputs of a Foveon sensor, the three outputs are more like white, yellow, and red. The top layer is all mutual information, you have to make the green and red that "contaminate" it go away before you can see the green.
 ...

I you mean that the color of processed earlier Sigma/Foveon sensors appealed to you, just like the colors of certain film manufacturers appeals to many, then that is a subjective opinion that one cannot argue.
EDIT - before everybody jumps all over me, let's do a little "napkin" math:
- The Sigma sensor is being calculated to come in at about 30MP equivalent.   Or about 25% better than a 24MP DSLR.  

- If you calculate out the geometry and interpolation losses in a Bayer sensor, and then factor in the AA filter, you end up with roughly a 0.65-0.7x multiplier for most DSLRs in each dimension.   This gives you a rough idea of how many actual full-color locations you can expect.  This allows for easier comparison between technology types.

- The Sony 24MP DSLR comes in at about 11 million actual pixels.  The Sigma has 14 million.  Or about the same 25% difference.
- The Fuji at 16MP has a closer to 0.8X multiplier (give or take) and comes in at about 11MP as well.  (scanned 35mm film is closer to 3-4MP, btw)
- The Sigma has a bit over 14MP and a 1.0x multiplier.  
Then you are ignoring the physics of how natural scenes tend to reflect light, and the way the human visual system works. If you can ignore those two factors, what is the application for a camera for you? Some industrial assembly-line quality control system?

-h
« Last Edit: May 26, 2011, 01:59:44 pm by hjulenissen »
Logged

Plekto

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 551
Re: What chance has Sigma's SD1?
« Reply #95 on: May 27, 2011, 02:50:25 am »

The interpolation losses for each type of sensor are something that you can't overcome, though.  Bayer "pixels" are really not full-color locations comparable, to say, pixels on a monitor, printer, or a scanner. So there are some unavoidable losses, which means that 24MP Bayer equals about 16MP Fuji.   The sigma is roughly equal to 30MP Bayer.

We're talking about minor differences between the two other than lens quality and features(which the DSLRs do win vs Fuji, no question about), but a ~12% in each dimension difference between the first two and the Sigma.  Like comparing 1440*960 to 1680*1050 on your monitor.  A slight difference, really.    What it comes down to is the optics, and to be honest, I think that the Fuji lens is not any worse than the stuff Sigma puts out.   

80%+ the quality of the Sigma for under $500.  Usability isn't a factor as the Sigma is *not* a pro camera in features and ease of use.  Well, the past models weren't.  Maybe this one will be different... *laugh*    (wow the past software was horrendous to use...)

It really is becoming who has the better assembly line at this point.  The Sony is a tremendous bargain at just under $2000 and with its better lenses will easily equal or beat the Sigma.   Sigma needed to price it at no more than 50% more than the Sony to stand a chance. 

In any case, arguing aside, the thing is dead in the water.  Maybe the talk of Sony coming out with their own take on the technology will pan out.  At least they will do a good job of it.
Logged

EsbenHR

  • Newbie
  • *
  • Offline Offline
  • Posts: 41
Re: What chance has Sigma's SD1?
« Reply #96 on: May 27, 2011, 05:28:00 am »

There are a number of issues with your post, but I'll just address that last.
Oh please do address the others.

The Foveon gains no advantage as a B/W sensor. Used that way, it's just a medium resolution 15 MP sensor.
I mean, it has the potential to be awesome 15MP B/W camera. Or you could say, an awesome APS B/W camera.
This obviously changes if you compared it to a modern pro-grade full-frame 35mm DSLR.

However, having played with a Phase Achromatic back, I can definitely say that a B/W camera where each pixel records a B/W value is great to work with.

I also stand by my comment that correcting a lens for chromatic aberration should be a lot easier with a Foveon than with a Bayer sensor. This will, eventually, be a limiting factor for the competition regardless of pixel size.
Logged

24x36

  • Newbie
  • *
  • Offline Offline
  • Posts: 21
Re: What chance has Sigma's SD1?
« Reply #97 on: May 27, 2011, 05:34:36 pm »

 :o

Sigma won't sell many of these at the ridiculous MSRP (or for that matter the still-astronomical "street" price related thereto).

The Foveon sensor tech has always been interesting to me, but they still haven't got it to a big enough format (i.e., 24x36 mm) to interest me. It's a joke that they think a less-than-half-frame format camera is going to compete with digital medium format. Sensor tech does not circumvent the laws of physics, after all, and there's no way that an APS-C format camera will be able to resolve 46MP or 30MP of detail, because the limits imposed by diffraction and practical lens resolution will cap it at something more like its actual photosite count (or less) in most cases.

How many (more like how few) photographers will tolerate a mid-range quality body with a relatively modest frame rate and buffer and a crappy interface (read: an APS_C viewfinder, and a less-than-100% one at that, without even the consolation prize of "Live View") at medium format/professional full frame format prices?! I suspect not many.

Another Achilles Heel is the proprietary Sigma lens mount. If the thing has ANY chance of selling in meaningful numbers, they should make one in each of Nikon and Canon mounts and ditch the proprietary Sigma mount, or make all three ONLY if they sell enough Sigma-mount cameras and lenses to justify it. Nobody with meaningful investments in Nikon or Canon gear (and the kind of money to afford cameras in this price range) is going to switch brands for a mid-range APS-C body camera with supposedly better than par image quality (the jury's still out on that, but we'll see) in what will probably be a more limited range of ISO values, given the Foveon track record.
Logged

DeanChriss

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 592
    • http://www.dmcphoto.com
Re: What chance has Sigma's SD1?
« Reply #98 on: May 28, 2011, 10:31:28 pm »

Theoretically, Foveon sensors have the potential for 3 times the resolution of a Bayer pattern sensor when both sensors are of equal size. Of course that's theory and you can never actually get to 3X. But 2X is very believable. I think these sensors have fantastic potential, but frankly I was unhappy when Sigma bought the intellectual property rights to this technology. In the hands of Nikon or Canon I think we'd now have much better cameras than we have now. But I don't trust Sigma quality based on reports I've read, and I've got a ton of money invested in non-Sigma lenses that I'm not willing to give up. Even putting all that aside, I'd never pay what they're asking for these cameras. In all, their pricing and proprietary lens mount make it a no-go.
Logged
- Dean

24x36

  • Newbie
  • *
  • Offline Offline
  • Posts: 21
Re: What chance has Sigma's SD1?
« Reply #99 on: May 28, 2011, 11:35:51 pm »

Theoretically, Foveon sensors have the potential for 3 times the resolution of a Bayer pattern sensor when both sensors are of equal size. Of course that's theory and you can never actually get to 3X. But 2X is very believable. I think these sensors have fantastic potential, but frankly I was unhappy when Sigma bought the intellectual property rights to this technology. In the hands of Nikon or Canon I think we'd now have much better cameras than we have now. But I don't trust Sigma quality based on reports I've read, and I've got a ton of money invested in non-Sigma lenses that I'm not willing to give up. Even putting all that aside, I'd never pay what they're asking for these cameras. In all, their pricing and proprietary lens mount make it a no-go.

http://www.luminous-landscape.com/tutorials/resolution.shtml

The resolution limit for APS-C sensors (as respects middle spectrum color) for diffraction-limited lenses at f8-f11 (the range that is a reasonable expectation for mass-produced lenses) is thirteen megapixels for f8, and seven megapixels for f11, based on physics. These limits won't be exceeded due to sensor technology, and irrespective of Foveon vs. Bayer "relativity," those maximum resolution limits are here to stay. When Foveon sensors were sporting less than 5 megapixels (of three layer pixels), the headroom, if you will, existed for the effective difference in resolving power to be seen (in terms of Foveon resolving like a higher megapixel count Bayer sensor). When you increase the megapixel count of the Foveon sensor to a point where you already are constrained (in terms of maximum potential resolution) by diffraction limits, you simply won't be getting more "resolution" based on Foveon vs. Bayer technology. We're already at the overkill level for megapixel count on APS-C sensors (at the 16MP level) with Bayer sensors. The real potential of Foveon will not be seen without a bump in sensor size (a 35mm Full Frame Foveon would have resolution limits of 29 megapixels for lenses "diffraction limited" at f8, and 16 megapixels for lenses "diffraction limited" at f11, which would allow more room for additional real-world resolution gains).

I was actually also kind of bummed when Sigma bought the Foveon technology, since it locks up the product in a minority lens mount from a small-time manufacturer that simply isn't going to make the best use of it. I agree that we would probably see much more enticing offerings with this sensor technology (and that some of the issues with it would have a much better chance of being resolved - pardon the pun) in the hands of the "Big Two." Sigma's price selection for this camera has turned the whole thing into something of a freak show, and their reasoning for the justification of the price is a joke.
Logged
Pages: 1 ... 3 4 [5] 6 7 8   Go Up