Theoretical digital sensor equivalent to 8x10?

[paulr]

Getting away from the science and math of this thread a similar type of argument/discussion has broken out in the 35mm arena since the arrival of the full frame sensor Nikon D800/800E. Advocates of the digital form of image making are stating that this camera not only produces superior images than traditional film (including 50ASA velvia), but challenges the superiority of medium and even large format film. Interestingly most of the wags supporting this view have never actually taken a picture with a film camera....

And their claims are being dismissed by people who have never seen the results of a d800. Not too many people have looked side by side.

I can speak somewhat knowledgeably about this particular comparison, having worked exclusively with 4x5 for fifteen years, and getting a d800 five months ago. The comparison actually parallels the one between 8x10 and a Phase One back quite closely.

Short version: I've been making 12"x18" proof prints from d800 files that are to my eye better—by a lot—than anything I've done or seen with 4x5. This is true only for one of the two projects I've been working on. The other is hand-held, in low light, and those prints look every bit like what we expect from small camera pictures.

I can attribute the superiority of the d800 prints primarily to the depth of field / diffraction calculus that I've mentioned before, and to the very high modulation and s/n ratio of the sensor. It also helps that there is no intermediate scanning or enlarging step to degrade the image.

It's possible that 12x18 is close to the sweet spot for this sensor. I would fully expect that if we made comparisons at larger and larger sizes, we'd hit a point where the 4x5 prints start to look better than the d800 prints. I can guess where that point would be, but haven't been able to test it. The biggest print I have for comparison is a 40x50 darkroom print from one of the black and white 4x5 negs. I think this size would be an interesting test for the d800. It would likely look worse than print from 4x5, and would certainly look different.

[paulr]

My concern with camera to print digital photography is that we may end up with vast numbers of extremely high resolution images that simply look the same.

This would be a failure of imagination, not technology. The files produced by these cameras are almost infinitely malleable. Unlike film, it's not possible to attribute a "look" to a digital sensor.

[bob carnie]

I just finished making some 40 x60 inch prints from the D800 that pretty much backs up the above.

[rdenney]

Remember... All of these supposed comparisons were developed by folks interested in selling digital imaging.

Not really true. But in any case, there are as many comparisons made by those trying to refute the validity of digital imaging as by those trying to promote it.

What I rarely see is a comparison based on what the photographer is trying to achieve, rather than what the equipment is capable of achieving.

For me, my digital prints usually come closer to my visualization than do my darkroom prints. Partly this is a limitation on technique. But it is also a limitation on what kinds of infrastructure I can support in my home, and what kind of time I can devote to photography. The compromises on time and infrastructure substantially limited what I could do in a darkroom, and I had more time in those days than I do now. The power tools give me more productivity up to a level of craftsmanship that is pretty good, versus the potential for craftsmanship I could never achieve anyway using non-power tools. In practice, it means I attain a higher level of mediocrity.

As to this issue, the question that I think is relevant is what would it take in a digital system to achieve what one can achieve using an 8x10 camera, and I think trying to answer that in absolute terms is intractable. I agree that to do what an 8x10 camera does, it would take an 8x10 sensor. Once we cross that bridge, we can have conversations about how many pixels that sensor needs to achieve a given outcome, but I sense that not everyone is prepared to cross that bridge.

For me, the point of large-format resolution is to maintain the sense of endless detail. I want the stuff in focus in my prints to give the effect that the closer one looks at the print, the more detail there will be. I'm prepared to refuse them a magnifying glass (beyond the bottom lens in their bifocals), but up to that point, I want it to hold up. When the detail turns fuzzy, it breaks that willingness to believe that the detail is endless.

This is not about sharpness at all. I have compared a fine duotone reproduction in Yosemite and the Range of Light to a Special Edition print of the same topic (Dogwoods...), and the duotone is made apparently sharper by the edges created by the dot pattern. But the Special Edition print retains the sense of endless detail. I suspect Paul is close to the mark with discussions of MTF, signal to noise ratio, and extinction limits, but I also suspect that what achieves the goal is a rather subtle interpretation of these, not microscopic comparisons or mathematical speculations.

Rick "who does the best he can with what he can live with" Denney

[Martin Courtenay-Blake]

I am actually getting the cash together to purchase a D800. I am sure it will be a satisfactory advancement over my current Pentax DSLR, and I'll be able to use my existing AF Nikkors. When I first considered the D800 I had a search on the interweb and found a superb comparison between the D800 and the then current EOS 5Dll. The Nikon seemed to have the edge over the Canon, mainly because of increased resolution. Both were then compared to images from a Pentax D645.....absolutely no contest. The images from the Pentax looked amazing. In pure pixel count the Pentax has only 10% more than the Nikon but it was like comparing a 35mm transparency with 5X4, the difference really was that great. The reviewer put it down to the actual size of the pixels and their ability to record detail more accurately.

If i could justify the price the Pentax would be my camera of choice. I don't know how long it will be but if a company was able to produce a 5X4 digital back using the same principals as Pentax have with their D645, i.e. pixel count per se is not the only way to produce stunning digital images the possibilities could be very enticing.

[rdenney]

If i could justify the price the Pentax would be my camera of choice.

Mine, too. I have at least a couple dozen lenses that could be used on one, including some that work really, really well. And including shift lenses in 45, 55, and 75mm.

But it won't make the same images as my 4x5, let alone an 8x10. None of the lenses has tilt, and none of them have that clean lack of lateral color and distortion that large-format near-symmetrical lenses provide (that's the secret in the sauce for the Mamiya 7).

But I still want one. Can't afford it, of course.

Rick "still buying lottery tickets" Denney

[paulr]

Remember... All of these supposed comparisons were developed by folks interested in selling digital imaging.

I've never had anyone even ask. Oustide these little technical communities, it's hard to find a collector or editor or curator who cares what kind of camera you used, unless there's something especially interesting about it.

[paulr]

The pentax 645d does produce a higher quality image than the Nikon, but I'd disagree that it's night and day. Comparing files on screen at 100% doesn't always clue you in to how prints are going to look. The extensive comparison I saw between the Nikon and the phase IQ160 showed a clear advantage to the Phase back (as you'd hope, for that kind of money). But the guy conducting the tests said that at print sizes below 30 inches there really wasn't much difference to talk about.

The Nikon can't quite match the resolution of the Pentax but beats it in dynamic range. Which quality is more important depends on what you're up to. For that matter, negative film still beats every digital sensor in dynamic range ... how much dr you need can help with any of these camera decisions.

The test I saw that few people were talking about is the Nikon vs. the pentax 67 and fuji 6x9 film cameras. This was a complete slaughter by the nikon, in terms of resolution, although the person conducting the tests liked working with film enough that he kept the fuji as his main camera.

[rdenney]

The pentax 645d does produce a higher quality image than the Nikon, but I'd disagree that it's night and day. Comparing files on screen at 100% doesn't always clue you in to how prints are going to look. The extensive comparison I saw between the Nikon and the phase IQ160 showed a clear advantage to the Phase back (as you'd hope, for that kind of money). But the guy conducting the tests said that at print sizes below 30 inches there really wasn't much difference to talk about.

The Nikon can't quite match the resolution of the Pentax but beats it in dynamic range. Which quality is more important depends on what you're up to. For that matter, negative film still beats every digital sensor in dynamic range ... how much dr you need can help with any of these camera decisions.

The test I saw that few people were talking about is the Nikon vs. the pentax 67 and fuji 6x9 film cameras. This was a complete slaughter by the nikon, in terms of resolution, although the person conducting the tests liked working with film enough that he kept the fuji as his main camera.

It is important to note just how demanding that much enlargement is of the lenses, however. I've seen frankly stunning prints made using a D800, but that photographer (who works at the local store and sells the things) also said that there are only two or three lenses in the Nikon lineup that can explore the capabilities of that sensor, when used at optimal aperture and with impeccable technique. I suspect the technique would still be required for the 645D, but the lenses would get by with two-thirds the resolution to get the same result. For the biggest prints I can make, that's the difference between a lens that must resolve 120 line pairs/mm versus a lens that resolves 80, both at good enough MTF to achieve good MTF at 5 line pairs/mm on the print. That difference cuts across some very significant boundaries, in terms of what available lenses are able to do.

But I'll stop there--this if off-topic.

Rick "back to the digital equivalent of 8x10" Denney

[paulr]

I don't think that's off topic at all, Rick. If you're comparing different formats it only makes sense to look at what lenses are available for each.

This point gets lost when people compare various film cameras to the medium format digital backs. The Schneider and Rodenstock lenses available for MF technical cameras are by a large margin the best lenses you buy. They're better than anything that's ever been made for large format, and better than anything that's ever been made for small format.

They're better than what you can get for the pentax 645, too, but those pentax lenses are still excellent.

This may be changing in the small format world, where there's all this renewed r&d energy. Nikon and Canon are both making some spectacular lenses (alongside a lot of not so spectacular lenses). Schneider and Zeiss have just announced small series of lenses for the upcoming year, designed to take live up to the new generation of sensors. They will not be cheap.

I've been using a Schneider PC Super Angulon shift lens on my Nikon. It's better than any other small camera lens that I've used, and better than my Schneider large format glass. But it's nowhere near as good as their current MF digital offerings. The new stuff coming out this year for the small cameras may change this.