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02-29-2008, 08:08 PM   #1
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APS-C vs FF again

Presently I am away from home and decided to take my Oly C7070 camera with me instead of the K10D. The reason, laziness!

In looking at the Raw images using SilkyPix, it was evident that things were not the same as they should be. The image sensor is 1/1.8 7mp and the resulting image quality resembled that of a disposable camera. That got me thinking and so I calculated the required lens resolution requirement in lp/mm delivered to the sensor to obtain maximum resolution. After that, I looked at the K100D, K10D, k20D and others. Here is what I came up with:

Oly C7070 215 lp/mm
K100D 63 lp/mm
K10D 83 lp/mm
k20D 99 lp/mm

K1D hopeful 66 lp/mm full frame 15mp

Nikon D3 59 lp/mm (full frame)

The Oly will always remain hopeless but it is evident that moving beyond the K100D starts to stress the lenses, reduces the diffraction limited F-number the and increases the affect of chromatic aberrations (the K20D would be diffraction limited at f5.6).

To obtain maximum image quality from the K20d will require very sharp lenses (which Pentax has produced in the past and are returning to now).

If you look at the proposed number for the K1D, it looks like a perfect fit for me. I can use all the lenses I have with a fair majority that meet or exceed the resolution requirements.

If Pentax were to produce it, I would be first in line.

I hope this does NOT mean WAR. It is simply my take. I used the same analogies year ago when I moved up from 35mm to 6X7/6X9 and 4X5 (Pixel peeping was done with a focusing magnifier). No way would a 35mm image hold up under enlargement compared to the others.

Bob Rapp

03-01-2008, 10:01 AM   #2
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QuoteOriginally posted by bobrapp Quote
Presently I am away from home and decided to take my Oly C7070 camera with me instead of the K10D. The reason, laziness!

In looking at the Raw images using SilkyPix, it was evident that things were not the same as they should be. The image sensor is 1/1.8 7mp and the resulting image quality resembled that of a disposable camera. That got me thinking and so I calculated the required lens resolution requirement in lp/mm delivered to the sensor to obtain maximum resolution. After that, I looked at the K100D, K10D, k20D and others. Here is what I came up with:

Oly C7070 215 lp/mm
K100D 63 lp/mm
K10D 83 lp/mm
k20D 99 lp/mm

K1D hopeful 66 lp/mm full frame 15mp

Nikon D3 59 lp/mm (full frame)

The Oly will always remain hopeless but it is evident that moving beyond the K100D starts to stress the lenses, reduces the diffraction limited F-number the and increases the affect of chromatic aberrations (the K20D would be diffraction limited at f5.6).

To obtain maximum image quality from the K20d will require very sharp lenses (which Pentax has produced in the past and are returning to now).

If you look at the proposed number for the K1D, it looks like a perfect fit for me. I can use all the lenses I have with a fair majority that meet or exceed the resolution requirements.

If Pentax were to produce it, I would be first in line.

I hope this does NOT mean WAR. It is simply my take. I used the same analogies year ago when I moved up from 35mm to 6X7/6X9 and 4X5 (Pixel peeping was done with a focusing magnifier). No way would a 35mm image hold up under enlargement compared to the others.

Bob Rapp
Film is not the same as a sensor. I can get the same resolution from a Ricoh GX100 as from a Pentax K10D, the difference is noise processing and its effect on detail. The Oly 7070 has an older generation image processor and the shots look mushy. Compare that with some shots from a Canon G9.

If I use APS lenses on an APS sensor I can get higher resolution from the lenses (smaller image circle) hence a 15MP APS camera will not have less resolution than a 15MP FF camera (unless I use a FF lens to test them both). They will be pretty much the same. However some of Canons and Nikons older lenses dont work so well on FF, so I dont see why Pentax would be any different.

What I do get from a FF sensor is larger pixels hence bigger well depth so theoretically less noise and more DR. Worth having for sure, but thats not the reason you were quoting.

And I think the price will be about double the K20D, so again nothing wrong with that if you have the money.

And also please note that diffraction limitations are a much bigger issue on MF where you have to stop down so much to get any DOF at all for landscape shots. F8 is fine on an APS digital, but F32 was often required on landscape shots.
03-02-2008, 06:59 AM   #3
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My experience using a lupe on 6x7 vs 35mm was 6x7 always lost the sharpness battle. Great 35mm lenses are sharper than any great medium format or large format lenses. Actually enlarge them and everything changes. Then small format loses.
One of the best ultrawide digital lenses around is the Olympus 7-14. Is as sharp as any Nikon or Canon wideangle on FF.
thanks
barondla
03-02-2008, 04:02 PM   #4
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The principle you quote is the same as that discussed here:

The Full-Frame Advantage

Lens resolution limitations will always show up in smaller formats vs. bigger ones, and the comparisons done in the above-referenced link are performed in digital, not film, so I don't think the film vs. digital sensor argument washes.

03-03-2008, 01:08 AM   #5
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As has already been pointed out, there's more at work here than you allow in your analysis. Yes, the Olympus camera is overtaxing its lens... I don't think there's any argument. But I don't think, for example, the K20d should have any trouble getting 100 lp/mm out of the lenses that most K20d users will own... it being the top camera, I imagine that its owners will likely have the DA* or Limited glass, and have no difficulty meeting the required resolution of he sensor. There is, of course, a limit at work here, and while the K20d hasn't reached it, it probably starts to get close. I'd imagine that 200 lp/mm would be too much to ask, so don't expect to see any 58mp APS-C cameras. That leaves, let us say for argument's sake, perhaps room to grow to a 32MP sensor, based on lens resolution alone. 150 lp/mm may be a bit generous, but I bet top Pentax glass lands around there. I haven't tested to find out, so YMMV, and may disprove me to a degree, but I doubt by much.

The real question, though, is whether or not an APS-C sensor can deliver a suitable, noise-free image at 33MP. My guess is that it cannot.

So we find that the limit for APS-C sensors lies between the 14.5 MP of the k20d and the 32MP of the theoretical lens limit, on the basis of image quality as delivered by a given pixel size. As photosites increase in size relative to the size of the pixel they occupy, this will change somewhat, and other advances in chipmaking help out as well, but I do think that we'll never see sensors that reach the resolution limits of the best Pentax glass. So yes, the APS-C format is resolution-limited.

But what format isn't? Film grains can only be made to be so small. APS-C cameras are what they are. And they are, by the way, the path that Pentax has invested heavily in. The best you can do is deal with it, because a 36x24 camera isn't coming anytime too soon from Pentax. Meanwhile, resolution is the worst possible argument to make against an APS-C camera. At 14.5 MP, the K20D outperforms the resolution of most films at the same ISO. You can generally print an APS-C image to a lerger size than you could a 35mm film negative with the same quality. We have enough resolution for any task we once would have used 35mm film for.

The great frontier, now, is dynamic range. If you want a better APS-C camera, don't think about the resolution limits of your lenses. Think about the bit-depth of your final RAW images and how many real-world stops of light you can cleanly record, without much noise. Not only are our current images sharper (more resolution-laden) than those of 35mm film at the same ISO, they also are less noisy, more often than not. Where they fall short is in dynamic range. Is the k20D a better camera because it has 14.5 MP than it would have been had it kept the K10D's 10.2 but had increased the size of the photosites and switched to CMOS technology? I would argue that it isn't. 10.2 MP is plenty of resolution for most applications. An extra couple stops of DR and a bump to 14 or 16-bit RAW would have been a much bigger jump, as far as I'm concerned.

Your point is still well-taken. My argument leads to the same conclusion... a larger sensor would yield better DR and a more robust image in general, given equal resolution. I just think that Pentax is so far from being in a place where a FF camera makes financial sense that it isn't worth discussing, and I'm tired of listening to any arguments in digital photography that hinge upon meeting the resolution requirements of this or that. P&S cameras never will meet them, and DSLRs almost always will. Let's stop chasing more MP and chase instead more DR. That's when we'll see a significant jump in quality.

Finally, in my experience, 6x7 slides on Provia 100F compared with a loupe to 35mm slides taken with Provia 100F perform basically the same, resolution-wise. The bigger negative is great if you want to print bigger, but the lenses of the systems (Canon EOS, Pentax K, and Mamiya RZ) seem to hit around the same marks in terms of lens resolution. Either I have some killer RZ glass, some shoddy Canon and Pentax glass, or format doesn't affect lens resolution as much as so many people claim.

Will
seeing your hope that this doesn't mean war and raising you a "we can just talk about this in a civil way."
03-03-2008, 04:21 AM   #6
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QuoteOriginally posted by wiyum Quote
As has already been pointed out, there's more at work here than you allow in your analysis. Yes, the Olympus camera is overtaxing its lens... I don't think there's any argument. But I don't think, for example, the K20d should have any trouble getting 100 lp/mm out of the lenses that most K20d users will own... it being the top camera, I imagine that its owners will likely have the DA* or Limited glass, and have no difficulty meeting the required resolution of he sensor. There is, of course, a limit at work here, and while the K20d hasn't reached it, it probably starts to get close. I'd imagine that 200 lp/mm would be too much to ask, so don't expect to see any 58mp APS-C cameras. That leaves, let us say for argument's sake, perhaps room to grow to a 32MP sensor, based on lens resolution alone. 150 lp/mm may be a bit generous, but I bet top Pentax glass lands around there. I haven't tested to find out, so YMMV, and may disprove me to a degree, but I doubt by much.

The real question, though, is whether or not an APS-C sensor can deliver a suitable, noise-free image at 33MP. My guess is that it cannot.

So we find that the limit for APS-C sensors lies between the 14.5 MP of the k20d and the 32MP of the theoretical lens limit, on the basis of image quality as delivered by a given pixel size. As photosites increase in size relative to the size of the pixel they occupy, this will change somewhat, and other advances in chipmaking help out as well, but I do think that we'll never see sensors that reach the resolution limits of the best Pentax glass. So yes, the APS-C format is resolution-limited.

But what format isn't? Film grains can only be made to be so small. APS-C cameras are what they are. And they are, by the way, the path that Pentax has invested heavily in. The best you can do is deal with it, because a 36x24 camera isn't coming anytime too soon from Pentax. Meanwhile, resolution is the worst possible argument to make against an APS-C camera. At 14.5 MP, the K20D outperforms the resolution of most films at the same ISO. You can generally print an APS-C image to a lerger size than you could a 35mm film negative with the same quality. We have enough resolution for any task we once would have used 35mm film for.

The great frontier, now, is dynamic range. If you want a better APS-C camera, don't think about the resolution limits of your lenses. Think about the bit-depth of your final RAW images and how many real-world stops of light you can cleanly record, without much noise. Not only are our current images sharper (more resolution-laden) than those of 35mm film at the same ISO, they also are less noisy, more often than not. Where they fall short is in dynamic range. Is the k20D a better camera because it has 14.5 MP than it would have been had it kept the K10D's 10.2 but had increased the size of the photosites and switched to CMOS technology? I would argue that it isn't. 10.2 MP is plenty of resolution for most applications. An extra couple stops of DR and a bump to 14 or 16-bit RAW would have been a much bigger jump, as far as I'm concerned.

Your point is still well-taken. My argument leads to the same conclusion... a larger sensor would yield better DR and a more robust image in general, given equal resolution. I just think that Pentax is so far from being in a place where a FF camera makes financial sense that it isn't worth discussing, and I'm tired of listening to any arguments in digital photography that hinge upon meeting the resolution requirements of this or that. P&S cameras never will meet them, and DSLRs almost always will. Let's stop chasing more MP and chase instead more DR. That's when we'll see a significant jump in quality.

Finally, in my experience, 6x7 slides on Provia 100F compared with a loupe to 35mm slides taken with Provia 100F perform basically the same, resolution-wise. The bigger negative is great if you want to print bigger, but the lenses of the systems (Canon EOS, Pentax K, and Mamiya RZ) seem to hit around the same marks in terms of lens resolution. Either I have some killer RZ glass, some shoddy Canon and Pentax glass, or format doesn't affect lens resolution as much as so many people claim.

Will
seeing your hope that this doesn't mean war and raising you a "we can just talk about this in a civil way."
wiyum

I agree with you, the DR is the issue, and I bet that will be the new race in the near future.

At 14 + MP's and above you need some serious computer power and lots of storage space. My K10D will print 13 x 19 images and the new K20D will print them better, with less noise and better DR.

There does come a point when enough is enough, and I like you would love to see the camera manufactures attack DR as the new frontier.


wll
03-03-2008, 06:38 AM   #7
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QuoteOriginally posted by wll Quote
wiyum

I agree with you, the DR is the issue, and I bet that will be the new race in the near future.

At 14 + MP's and above you need some serious computer power and lots of storage space. My K10D will print 13 x 19 images and the new K20D will print them better, with less noise and better DR.

There does come a point when enough is enough, and I like you would love to see the camera manufactures attack DR as the new frontier.


wll
I think they will but its a lot harder than most think. Sensors are linear in response, so even though doubling the size of the pixel gives you twice the well depth, it also gives you twice the noise and by the time you have imposed an S curve on the linear response curve you have only gained about 1/2 stop at most.

Fuji are about the only folk who have done anything to overcome this, but sadly their sensor had fairly poor resolution compared to the competition. However its a more effective and cheaper approach than the full frame argument, but it doesnt achieve the same high ISO noise.
03-04-2008, 09:14 PM   #8
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Interesting how I keep hearing that digital resolution has equaled or surpassed 35mm film, while the numbers even in the articles making such statements don't bear this out. According to the Popular Photography Canon EOS 1Ds Mk III review, ISO 100 film resolution ("tested" according to PopPhoto) tests at 3000 lines, while the EOS-1Ds III (21.1 Megapixels!) tests out to 2830 Lines. The K20D has 2350 lines, which is obviously even further short of that mark.

In that PopPhoto EOS 1Ds III review, they go on about "with such a pixel filled sensor" how important the latest/greatest lenses are, since an "older or cheaper" lens would be like "dialing down the megapixel count" - interesting that those older/cheaper lenses weren't an issue with film when film, according to their own numbers, has even MORE resolution.

Subjective image quality is another issue, and digital and film are different mediums with different attributes. But I guess I've tired of the rush to declare digital's "resolution" to be equal to or better than film when it hasn't gotten there yet even with the (currently) highest megapixel count dSLR in existence.

03-05-2008, 01:52 AM   #9
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QuoteOriginally posted by 24X36NOW Quote
In that PopPhoto EOS 1Ds III review, they go on about "with such a pixel filled sensor" how important the latest/greatest lenses are, since an "older or cheaper" lens would be like "dialing down the megapixel count"
I am sure that Canon wrote this portion of the review.

Bob
03-05-2008, 02:47 AM   #10
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What can't people just go out and enjoy taking images without worrying about this sort of stuff?

As we get older our eyes start to deteriorate, a significant number of photographers wear glasses so why get bogged down by Pixel peeping?
03-08-2008, 07:30 PM   #11
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QuoteOriginally posted by bobrapp Quote
Presently I am away from home and decided to take my Oly C7070 camera with me instead of the K10D. The reason, laziness!

In looking at the Raw images using SilkyPix, it was evident that things were not the same as they should be. The image sensor is 1/1.8 7mp and the resulting image quality resembled that of a disposable camera. That got me thinking and so I calculated the required lens resolution requirement in lp/mm delivered to the sensor to obtain maximum resolution. After that, I looked at the K100D, K10D, k20D and others. Here is what I came up with:

Oly C7070 215 lp/mm
K100D 63 lp/mm
K10D 83 lp/mm
k20D 99 lp/mm

K1D hopeful 66 lp/mm full frame 15mp

Nikon D3 59 lp/mm (full frame)

The Oly will always remain hopeless but it is evident that moving beyond the K100D starts to stress the lenses, reduces the diffraction limited F-number the and increases the affect of chromatic aberrations (the K20D would be diffraction limited at f5.6).

To obtain maximum image quality from the K20d will require very sharp lenses (which Pentax has produced in the past and are returning to now).

If you look at the proposed number for the K1D, it looks like a perfect fit for me. I can use all the lenses I have with a fair majority that meet or exceed the resolution requirements.

If Pentax were to produce it, I would be first in line.

I hope this does NOT mean WAR. It is simply my take. I used the same analogies year ago when I moved up from 35mm to 6X7/6X9 and 4X5 (Pixel peeping was done with a focusing magnifier). No way would a 35mm image hold up under enlargement compared to the others.

Bob Rapp
Very good analysis, and that is why many knowledgeable photographers recognize the value of full frame DSLR cameras and at the same time dread the megapixel race. Many professionals in fact have picked the 12mp Canon 5D over the more expensive 16mp 1DS MKII because of superior image quality provided by the 5D, and because the 5D is more compact. A 15mp Pentax full frame should be similar in image quality to the 5D, given the advances in sensor design since the introduction of the 5D.

It is certainly possible that Pentax will make a 15mp K1D full frame, and I hope it does. However, it may want to compete with the likes of the Sony 24mp full frame instead, since it can probably charge more money for a high pixel count full frame than to try to compete with the low priced 5D or its similarly low priced successor. As Pentax found out, charging less (e.g. the K10D) can sometimes make more sense than charging too much (e.g. *ist D). Frankly, I think Sony and Pentax are charging too much for the A700 and K20D, respectively, and both will probably lose market share in 2008, unless they quickly slash prices.
03-09-2008, 07:49 PM   #12
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APS-C 10mp resolution is more than good enough for most people's needs. But DOF? Check out this thread:

85 f1.2L...show your shots - FM Forums

'nuff said.
03-10-2008, 05:49 PM   #13
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QuoteOriginally posted by *isteve Quote
Film is not the same as a sensor. I can get the same resolution from a Ricoh GX100 as from a Pentax K10D, the difference is noise processing and its effect on detail. The Oly 7070 has an older generation image processor and the shots look mushy. Compare that with some shots from a Canon G9.

If I use APS lenses on an APS sensor I can get higher resolution from the lenses (smaller image circle) hence a 15MP APS camera will not have less resolution than a 15MP FF camera (unless I use a FF lens to test them both). They will be pretty much the same. However some of Canons and Nikons older lenses dont work so well on FF, so I dont see why Pentax would be any different.

What I do get from a FF sensor is larger pixels hence bigger well depth so theoretically less noise and more DR. Worth having for sure, but thats not the reason you were quoting.

And I think the price will be about double the K20D, so again nothing wrong with that if you have the money.

And also please note that diffraction limitations are a much bigger issue on MF where you have to stop down so much to get any DOF at all for landscape shots. F8 is fine on an APS digital, but F32 was often required on landscape shots.
Noise and DR are, in addition to resolution, parts of the equation termed "image quality." The original poster was concerned about image quality, and pointed out that the increased resolution of a high megapixel count sensor will not translate into higher resolution in the image. Of course, the smaller pixels of the high pixel count camera will result in more noise and less DR, which would translate into poorer image quality. So even though DR and noise were not cited explicitly, they were implicit in his argument for a low pixel count full frame, since low pixel count translates into larger individual pixels, which are key to low noise and high dynamic range.
03-10-2008, 07:38 PM   #14
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QuoteOriginally posted by barondla Quote
One of the best ultrawide digital lenses around is the Olympus 7-14. Is as sharp as any Nikon or Canon wideangle on FF.
thanks
barondla
And, fortunately for Oly people, Olympus considers getting rid of CA very important, and Pentax lens designers just don't think its a big deal, and leave it substantially in most lenses.

Even Oly's new 70-300mm $350 consumer zoom has eliminated CA, but the Pentax 55-300mm, and $1000 200mm have good amounts of it.

It is a big deal.
03-11-2008, 04:56 AM   #15
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QuoteOriginally posted by bobrapp Quote
Oly C7070 215 lp/mm
K100D 63 lp/mm
K10D 83 lp/mm
k20D 99 lp/mm
K1D hopeful 66 lp/mm full frame 15mp
Nikon D3 59 lp/mm (full frame)
It may be interesting to cite an official quote from Carl Zeiss AG here:
QuoteQuote:
  • 35mm lenses of the ZM series resolve up to 400 lp/mm on film. For the ZF series, we have measured up to about 300 lp/mm.
  • Middle format lenses by Carl Zeiss for Hasselblad resolve up to 280 lp/mm (Superachromat 5,6/250).
  • Large format lenses by Carl Zeiss resolve up to 160 lp/mm (Biogon 4,5/75).
Source: Willkommen bei Photo- und Filmobjektiven von Carl Zeiss
Translation: myself.

This may well be as good as it may ever get, so lets compute the maximum amount of pixels (1 (rather than 2) pixels per lp because the eye won't resolve 5% contrast anymore) from it:
  • 35mm (30x30mm): 9k x 9k, 81 MPixel
  • MF (150x150mm): 42k x 42k, 1700 MPixel
  • LF (230x230mm): 37k x 37k, 1400 MPixel
The human eye, if allowed to wander around an image (what it does...), is 81 MPixel.

So, 35mm full frame format is the smallest format to fully exploit the human eye's resolution capabilities. Useless however, as long as it cannot be displayed or printed

Maybe, an APS-C lens would resolve 500 lp/mm. But for normal lengths and shorter, not with a 35mm mount (distance of rear lens to sensor). Olympus has a small advantage here, Leica M a big one.
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