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Author Topic: What chance has Sigma's SD1?  (Read 48983 times)

nightfire

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Re: What chance has Sigma's SD1?
« Reply #40 on: May 23, 2011, 03:23:59 pm »

Looking at how the Fuji X100 sold at a premium in relation to its specs, maybe some Sigma execs indeed believed they could pull this off too.
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Bart_van_der_Wolf

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Re: What chance has Sigma's SD1?
« Reply #41 on: May 23, 2011, 03:32:44 pm »

Excellent explanation, thanks.

Eduardo,

Unless you are being cynical, you were misinformed.  There is almost nothing in those statements that's correct (as to why, see my earier response), which is indeed an accomplishment.

Cheers,
Bart
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hjulenissen

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Re: What chance has Sigma's SD1?
« Reply #42 on: May 23, 2011, 04:22:38 pm »

Irrelevant, because a Bayer CFA sensor captures Luminance at each sensel position (the spectral bands that are filtered out are calculated and added back in at demosaicing time), only attenuated by the peak transmission of the filter. The Foveon sensor also only uses 1/3rd of the spectrum per color, although it only loses light to the increased amounts of circuitry that produces a smaller fill factor, and the other unutilized photon energy.

Cheers,
Bart
Not following you here.

A theoretic, ideal Bayer sensor must still "throw away" a fraction of the light hitting the sensor area. In practice it will be affected by the selectivity of the color filters, but let us say that 2/3 is thrown away for simplicity.

A theoretic, ideal Foveon sensor need not "throw away" any light, since all light hitting a sensor area could be counted and classified as either red, green or blue.

As a camera is basically a photon-counter (counting where the photons hit, and approximate wavelength), counting all photons seen for a given lense sounds better than not counting them all.

We could compare the two sensors using identical sample grids, and conclude that the idealized Foveon sensor could do more spatial lowpass filtering to effectively remove noise while still having the spatial detail of the Bayer sensor + AA-filter. For simlicity we could assume a 2x2 pixel rectangular filter in the red and green channels, and a effective sqrt(2)xsqrt(2) pixel filter in the green channel.

In practice, limitations of current Foveon technology seems to make this theoretical exercise irrelevant. The problem is not the theoretical gains of having cosited subpixels, but making those subpixels small enough and still of sufficient quality and low enough price...
« Last Edit: May 23, 2011, 04:26:25 pm by hjulenissen »
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Rhossydd

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Re: What chance has Sigma's SD1?
« Reply #43 on: May 23, 2011, 05:19:43 pm »

Looking at how the Fuji X100 sold at a premium in relation to its specs, maybe some Sigma execs indeed believed they could pull this off too.
I'm sure Fuji would claim the X100 hasn't a 'premium' price, but it's cost can be justified by it's unique spec and niche market.
For me it was too much and at least 300 in excess of what I'd consider a reasonable price. But if I'd really liked the feel and spec of it*, 300 would have been an affordable premium to pay for it. Michael's assessment of the SD1 being at least $8k too much seems about right and is simply an outrageous and unaffordable premium to pay for the camera.
Maybe Bernard's insight into the specialised nature of the market in Japan might be correct and Sigma's pricing strategy is squarely aimed for the yen paying gullible.



*If they'd got the size right I'd have been in the queue to buy one at an even higher price. I still want a digital version of a truly compact 35mm camera like the Fuji super DL mini/Minox 35/Rollei 35, but it still seems no nearer than it did five years ago :-(
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Bart_van_der_Wolf

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Re: What chance has Sigma's SD1?
« Reply #44 on: May 23, 2011, 05:23:00 pm »

Not following you here.

A theoretic, ideal Bayer sensor must still "throw away" a fraction of the light hitting the sensor area. In practice it will be affected by the selectivity of the color filters, but let us say that 2/3 is thrown away for simplicity.

A theoretic, ideal Foveon sensor need not "throw away" any light, since all light hitting a sensor area could be counted and classified as either red, green or blue.

It's simple, really.

Both a Bayer Color Filter Array (CFA) sensor and a Foveon sensor utilize 1/3rd of the spectrum (broadly speaking) for 1/3rd of the RGB output pixel data. Per output pixel,the CFA supplements the 2/3rd of the filtered spectrum by demosaicing, the Foveon has an actual recording of the Luminance in that 2/3rd of the spectrum.

So, e.g. a Green filtered CFA sensel conceptually receives the same amount of the spectrum (= Luminance) as the Green filtered Foveon layer. The only effective difference is in the transmission of the respective CFA filter in the spectal band versus the reduced Fill-factor of the corresponding spectrally sensitive Foveon layer, IOW the quantum efficiency. There is no 3:1 difference in sensitivity due to the technology itself.

Cheers,
Bart
« Last Edit: May 23, 2011, 05:25:03 pm by BartvanderWolf »
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uaiomex

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Re: What chance has Sigma's SD1?
« Reply #45 on: May 23, 2011, 06:57:49 pm »

Unfortunately I wasn't. I may be misinformed. Actually, I thought his info was accurate and that the form he wrote it "explained" it, and that's what I meant.  My response was mainly to question him about his statement saying that the aps-c sensor in the SD1 is some sort of de-facto medium format. It is very possible that the tech data is more that I can understand, but for sure I know apples from oranges.  :D
Eduardo


Eduardo,

Unless you are being cynical, you were misinformed.  There is almost nothing in those statements that's correct (as to why, see my earier response), which is indeed an accomplishment.

Cheers,
Bart
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Bart_van_der_Wolf

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Re: What chance has Sigma's SD1?
« Reply #46 on: May 23, 2011, 07:15:42 pm »

Unfortunately I wasn't. I may be misinformed. Actually, I thought his info was accurate and that the form he wrote it "explained" it, and that's what I meant.  My response was mainly to question him about his statement saying that the aps-c sensor in the SD1 is some sort of de-facto medium format. It is very possible that the tech data is more that I can understand, but for sure I know apples from oranges.  :D/

Hi Eduardo,

No problem. The benefit of a forum like this is that opinions can/will be challenged, and it will benefit all.
There is a significant amount of disinformation about the Foveon sensor going around, I just try to demystify it with arguments and proof.

Cheers,
Bart
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John Camp

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Re: What chance has Sigma's SD1?
« Reply #47 on: May 23, 2011, 07:39:12 pm »

After reading Michael's analysis of the SD1 pricing blunder, I find little reason to disagree with him. However, I think the SD1 would have failed anyway -- it's simply too little, too late, even at $2,000. Sigma keeps trying to suggest that it's producing a pro-level camera with revolutionary technology, and reviewers keep saying, "No, you're not." The lenses aren't as good, the system isn't as complete, the software isn't anything special, in comparison to other pro-level competitors, or even the better prosumer cameras like Pentax. Although some are enamored with the sensor tech, it's more the *idea* of the thing, rather than actual performance, that seems to interest people. In terms of performance, Foveons never really kept up with more conventional sensors...not that that perhaps they couldn't have, it's just that in Sigma's hands, they haven't.

It made me wonder if some discouraged Sigma exec didn't do an analysis of the completed camera, and concluded, "You know what? We have just labored mightily and produced a POS, and everybody is going to know it, and it's gonna die an ugly death. Is there anything we can do to attract attention to this thing, to stir up some controversy?"   
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KevinA

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Re: What chance has Sigma's SD1?
« Reply #48 on: May 24, 2011, 12:18:00 am »

After reading Michael's analysis of the SD1 pricing blunder, I find little reason to disagree with him. However, I think the SD1 would have failed anyway -- it's simply too little, too late, even at $2,000. Sigma keeps trying to suggest that it's producing a pro-level camera with revolutionary technology, and reviewers keep saying, "No, you're not." The lenses aren't as good, the system isn't as complete, the software isn't anything special, in comparison to other pro-level competitors, or even the better prosumer cameras like Pentax. Although some are enamored with the sensor tech, it's more the *idea* of the thing, rather than actual performance, that seems to interest people. In terms of performance, Foveons never really kept up with more conventional sensors...not that that perhaps they couldn't have, it's just that in Sigma's hands, they haven't.

It made me wonder if some discouraged Sigma exec didn't do an analysis of the completed camera, and concluded, "You know what? We have just labored mightily and produced a POS, and everybody is going to know it, and it's gonna die an ugly death. Is there anything we can do to attract attention to this thing, to stir up some controversy?"   

Lets give it a chance.
What if it is MF quality but without the moire, it could look a bargain? If it only matches top Canikon quality then they will have to give them out free with a Burger or something. Lets give it a few weeks before writing the obituary.
Not so long ago the The Leica "S" was going to drag the company under when it was announced according to many. The Sigma will hit the streets at much less than the price given out, I reckon they are just enjoying the attention, everyone is talking about and scratching their heads, so far it's great publicity.

Kevin.
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Josh-H

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Re: What chance has Sigma's SD1?
« Reply #49 on: May 24, 2011, 12:27:36 am »

Quote
so far it's great publicity.

I wouldn't call it 'great' publicity. More like a 'Firestorm'

Edit - DP Review has a hands on preview of the Sd1 now on their site
http://www.dpreview.com/previews/sigmasd1/

They offer little in the way of conclusions with this initial 'preview' - I guess more to come...

Initial Conclusion
Quote
The SD1 is a very straightforward camera to shoot, as you'd expect from its very still-image-focused feature set. Some of its operation is a little eccentric, such as the inability to directly access exposure compensation using one of the control dials in the A and S modes, but not in a hugely problematic fashion. We're also a bit surprised to see metering mode given its own button in preference to White Balance, and that its position is considerably easier to reach than the more regularly used ISO button.

It seems rather odd to have two distinct quick access systems, especially as neither of them makes great use having twin dials available (the dials remain dedicated to their shutter or aperture roles when in the Func. menu, and simply flick back and forth between the two screens of the QS menu). In fact it's only really in the menus (where the front dial scrolls up and down the menus and the rear dial scrolls left and right across menu tabs), that the camera's twin dials are really fully utilized.

Overall there's little to gripe about though - it's all pretty logical and well-behaved. However the ability to make a few customization decisions about dial operation, or to rededicate either the QS or Func button, would help the camera to suit even more tastes.
« Last Edit: May 24, 2011, 01:04:28 am by Josh-H »
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Rhossydd

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Re: What chance has Sigma's SD1?
« Reply #50 on: May 24, 2011, 01:57:03 am »

Not so long ago the The Leica "S" was going to drag the company under when it was announced according to many.
The difference is that Leica are a premium brand that could justify the price. There was also no doubt that any lenses made for the camera would be of the highest quality and allow the body to deliver it's full potential.
Quote
The Sigma will hit the streets at much less than the price given out, I reckon they are just enjoying the attention, everyone is talking about and scratching their heads, so far it's great publicity.
Great publicity ? I don't think so, they've made themselves look stupid and out of touch with this pricing, plus there's been a lot of negativity towards the brand overall. Do Sigma really want all their performance and quality control issues aired so publicly ? It certainly won't help their existing reputation and sales, let alone assist potential sales of the new body.
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viewfinder

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Re: What chance has Sigma's SD1?
« Reply #51 on: May 24, 2011, 03:51:54 am »

Perhaps this is an attempt at  a 'clever' marketing stunt and we have not had the 'punch line' yet.....

Perhaps the idea is that the camera IS suposed to be massively overpriced,...and then carefully selected users will be granted the pivaledge to buy for 'only' 2000USD...  That way they will be able to sell at what the camera is actually worth and have no shortage of buyers who will clamber for something they have been persuaded to believe is 'exclusive'.....

.....I can just hear the conversations at golf  and photo club meetings;......."I had the chance to get the ten thousand dollar Sigma at Gold club price, so I just snapped one up to see what it's like".......

I know two people who use previous Sigma DSLR's and they are both retired business men who don't know one end of a camera from the other. let alone recognise image qualities,...but they both tell people how exclusive and wonderful their Sigmas are, and how much better than a Canon or Nikon could ever be.    Perhaps the Gold Club price will be offered to existing Sigma users first,...I'm sure my two aquaintances would jump at the chance to buy.
« Last Edit: May 24, 2011, 04:05:03 am by viewfinder »
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KevinA

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Re: What chance has Sigma's SD1?
« Reply #52 on: May 24, 2011, 04:04:44 am »

The difference is that Leica are a premium brand that could justify the price. There was also no doubt that any lenses made for the camera would be of the highest quality and allow the body to deliver it's full potential.Great publicity ? I don't think so, they've made themselves look stupid and out of touch with this pricing, plus there's been a lot of negativity towards the brand overall. Do Sigma really want all their performance and quality control issues aired so publicly ? It certainly won't help their existing reputation and sales, let alone assist potential sales of the new body.

Leica are a premium brand alright, but it was still going to be there toll on the death bell.
I doubt I could have named a Sigma camera before this, now the World and his dog know about the SD1, what ripples did any of their other cameras make on release. Is there a forum not talking about the new Sigma in great length. Hopefully this is a new generation Foveon which might take things on a notch or two. The traditional camera makers don't exactly set the scene alight with innovation these days. I am certainly going to keep an eye on the new Sigma I doubt it will ever be priced on the shop floor anywhere near the announced ticket price. Give it a couple of days and it will be announced as some kind of mix up.
I quite like the idea of a high res camera with no AA filter and little chance of moire, where else can you get that? My biggest concern is the two Sigma lenses I own, don't exactly entice me to buy more of them.

Kevin.

Kevin.
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hjulenissen

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Re: What chance has Sigma's SD1?
« Reply #53 on: May 24, 2011, 04:22:07 am »

It's simple, really.

Both a Bayer Color Filter Array (CFA) sensor and a Foveon sensor utilize 1/3rd of the spectrum (broadly speaking) for 1/3rd of the RGB output pixel data. Per output pixel,the CFA supplements the 2/3rd of the filtered spectrum by demosaicing, the Foveon has an actual recording of the Luminance in that 2/3rd of the spectrum.

So, e.g. a Green filtered CFA sensel conceptually receives the same amount of the spectrum (= Luminance) as the Green filtered Foveon layer. The only effective difference is in the transmission of the respective CFA filter in the spectal band versus the reduced Fill-factor of the corresponding spectrally sensitive Foveon layer, IOW the quantum efficiency. There is no 3:1 difference in sensitivity due to the technology itself.

Cheers,
Bart
Do you agree that (using your numbers) 1/3 of the photons are counted in a Bayer sensor, while all photons are counted in a Foveon sensor?

What you are saying is that the "per sensel" signal/noise level should (theoretically, ideally) be the same, and i agree. What I am saying is that the Foveon sensor would have 3x as many sensels for a sensor of same size and same pixel grid, therefore being able to measure a larger fraction of the signal (energy).

If you have the choice between doing election polls on a group of 100 individuals, or 3 groups of 100 individuals, which would be a less "noisy" prediction of a population of millions?

-h
« Last Edit: May 24, 2011, 04:27:45 am by hjulenissen »
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Bart_van_der_Wolf

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Re: What chance has Sigma's SD1?
« Reply #54 on: May 24, 2011, 05:47:39 am »

Do you agree that (using your numbers) 1/3 of the photons are counted in a Bayer sensor, while all photons are counted in a Foveon sensor?

Yes, in principle that's the case due to the CFA. The remaining 2/3rds are not contributing to the same sensel position, although due to the AA-filter some is used in neighboring sensels. I left out that latter aspect earlier to not complicate the matter too much, but the Bayer CFA is really elegant in design and allows a significant level of reconstruction of the missing information (although not perfect, also due to different sampling densities of Green versus Red and Blue). Fortunately, chromatic information is generally lower spatial frequency data compared to Luminance, which mimics human vision a bit.

Quote
What you are saying is that the "per sensel" signal/noise level should (theoretically, ideally) be the same, and i agree. What I am saying is that the Foveon sensor would have 3x as many sensels for a sensor of same size and same pixel grid, therefore being able to measure a larger fraction of the signal (energy).

That's correct. An unfortunate side effect is of course that the uncompressed Raw data stream is 3x as large, burst shots require to move more data around (limiting the no. shots/sec), and memory cards fill up faster. On the plus side, the file does slightly better when upsampling to a larger size, because the chroma resolution is a bit higher.

Quote
If you have the choice between doing election polls on a group of 100 individuals, or 3 groups of 100 individuals, which would be a less "noisy" prediction of a population of millions?

If they were all monochrome samples, the more the merrier. However, we're dealing with filtered spectral bands here. Depending on scene content, some colors may have a low contribution with accompanying photon shot noise levels. And in the case of the Foveon sensor, the channel separation is very poor according to the Foveon documentation. This means that a lot of matrix math with huge negative coefficients is needed, which increases noise a lot. In addition, the fill factor of a Foveon sensor is rather small due to the additional connections and transfer gates (also needs to store 3 charges in the same small space), so the sensels saturate quickly. The comparison of noise performance is too complex to be explained with a simplified model. In practice though, the Foveon sensors have had limited high ISO quality compared to alternative technologies.

Cheers,
Bart
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hjulenissen

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Re: What chance has Sigma's SD1?
« Reply #55 on: May 24, 2011, 06:50:54 am »

Yes, in principle that's the case due to the CFA. The remaining 2/3rds are not contributing to the same sensel position, although due to the AA-filter some is used in neighboring sensels.
If the AA filter is linear, space-invariant and wavelength invariant, the spreading should be equal into and out of any given sensel (area), meaning that no gain or loss occurs in terms of total number of photons counted?
Quote
If they were all monochrome samples, the more the merrier. However, we're dealing with filtered spectral bands here.
Let me rephrase. Would you rather sample the wavelength of 400 to 550 nm within a 2n*2m micron area by:
1. Measuring all photons within a n*m area (blocking out the remaining 3 n*m),
2. Measuring 1/4 of the photons within a 2n*2m micron area (hypothetical square AA-filter),
3. Measuring all photons within a 2n*2m area distributed on 4 sensels? (hypothetical foveon)

I would prefer the latter, as it would give me more photons.
Quote
The comparison of noise performance is too complex to be explained with a simplified model. In practice though, the Foveon sensors have had limited high ISO quality compared to alternative technologies.

Cheers,
Bart
I agree about all of your practical concerns about Foveon. My objections were about the crude idealized model and how it would (could) have worked.

« Last Edit: May 24, 2011, 08:10:04 am by hjulenissen »
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BernardLanguillier

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Re: What chance has Sigma's SD1?
« Reply #56 on: May 24, 2011, 07:15:50 am »

More than often, the price defines the level of attractiveness of something.

My 2 bets are:
1. The SD1 will be a success in Japan,
2. Sigma will make more money with it selling for 9000 US$ than they would have with it priced at 2000 US$.

Indeed, I believe that most people interested in this camera in Japan don't really care about the price. They are looking for differentiation. The price actually helps them

Cheers,
Bernard

uaiomex

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Re: What chance has Sigma's SD1?
« Reply #57 on: May 24, 2011, 02:53:58 pm »

If this turns to be true that would be another reason to think that photography indeed is starting to suck!
Eduardo

More than often, the price defines the level of attractiveness of something.

My 2 bets are:
1. The SD1 will be a success in Japan,
2. Sigma will make more money with it selling for 9000 US$ than they would have with it priced at 2000 US$.

Indeed, I believe that most people interested in this camera in Japan don't really care about the price. They are looking for differentiation. The price actually helps them

Cheers,
Bernard

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jimk

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Re: What chance has Sigma's SD1?
« Reply #58 on: May 24, 2011, 05:21:55 pm »

street price will be less just wait till they start shipping  :)
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BernardLanguillier

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Re: What chance has Sigma's SD1?
« Reply #59 on: May 24, 2011, 08:03:48 pm »

street price will be less just wait till they start shipping  :)

Yep, already at 630.000 Yen in Japan.

That's even smarter in fact... you have an exclusive camera with the best sensor in the world (claim I predict the owners will lay), one that is worth 10.000 US$, but you did in fact get it for a lot less... still you know people think it is worth 10.000 US$. :)

Cheers,
Bernard
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