We're getting close to a number of limits, both on possible DSLR image quality and on what we actually need. First of all, how big do you intend to print? This is different for each photographer, but anything above 16x24 inches is probably uncommon with prints above 24x36 being very rare. Most modern high-pixel count DSLRs will produce a gallery-quality 16x24 inch print, and there's at least one, and maybe more, that prints 24x36 inch prints with superb detail (stands up to inspection from 8 inches away). I shoot the D3x, and can say from experience that it prints 24x36 inches very well. The Alpha 900 or one of the modern Canons might as well, but I've never tried it. Any more detail extraction (a combination of resolution, AA filtration and lens quality) than the D3x is capable of will only be visible on VERY large prints (probably beyond what a 24 inch printer can do). 44 inch printers are a major commitment, in terms of price, space for the equipment and display space for the prints. A 44 inch printer is roughly the size and weight of an upright piano, and the images it produces cannot be matted on standard boards or displayed on most walls (framed, a 40x60 inch print is close to 6 feet wide). Even a 24 inch printer sits on its own stand, and is an ugly piece of furniture! I've just figured out where one is going to go in my workroom. For what I do (landscapes and macros), a DSLR with detail sufficient for 24x36 inch printing, plus wide dynamic range and a beautiful tonal scale is what I need, and I bought it a few weeks ago. I was only willing to spend the money because I feel that it is a 5-10 year camera (I can't see what I'd really use that it can't do).
The newest DSLRs are also giving us detail over a very wide dynamic range - wider, in fact than film ever did. The Zone System accounts for 11 stops of range (Zones 0 through X), but only 9 of them hold detail (X is paper white and 0 is maximum black without detail). Some modern DSLRs are holding good detail over 10 stops, maybe approaching 11 with careful post-processing (we've added 1 to 2 stops beyond where the Zone System was meant to go). There's nothing that says that a photographer couldn't USE, say 14 stops and bring them into the smaller range of the printer in post-processing , but it's a tool we've never had before. The quality of those tones is rapidly increasing - the banding and harsh transitions that used to scream "digital" are pretty much gone.
As we reach these high image qualities (the D3x is easily equivalent to a 6x9 cm film camera, better in some ways, and the higher resolution medium-format backs equal 4x5 film), the laws of physics are beginning to rear their ugly heads and say "Thus far shall you come, but no farther". Between diffraction, lens resolution limits and unavoidable quantum noise, the maximum EFFECTIVE resolution of a FF35 sensor is somewhere between 25 and 40 megapixels. You can certainly build a higher resolution sensor (the pixel density of an average digital compact would be around 300 MP if spread over a FF35 sensor), but you won't get a commensurate improvement in image quality. Even at the low end of the 25 to 40 mp range, lenses are affected by diffraction above about f8 (so absolute maximum image quality means staying between f4 and f8). By the upper end of that range, the effect of diffraction appears by f5.6, so a 40 mp DSLR would need superb lenses used between f4 and f5.6 to extract maximum detail.
Quite a few cameras are in the lower end of this range (not only the 20+MP FF35 DSLRs, but 10-12 MP APS DSLRs and 50ish MP MF backs), and the best of them are capable of very good quality per pixel with careful handling. Leaving aside digital compacts, there have only been a few penetrations into the upper reaches of this range of pixel densities (all are APS DSLRs, and the most notable is the Canon EOS-50D (which would be 38 mp if full-frame)). The 50D has received mixed reviews, but one review it has NOT gotten is "the full effect of the extra resolution above the 40D is noticeable". Some reviewers say that the overall image quality of the 50D is actually not as good as the older 40D, while others say that it has a noticeable positive difference, but less than one would expect from the raw numbers. The 50D is actually easier to get good quality out of than a full-frame DSLR of the same pixel density would be, because it doesn't need lenses with that level of resolving power over as large an area. A full-frame 38 mp DSLR would display its maximum image quality in vanishingly few situations!
There are several possible directions to go, given that "more resolution" will soon be ineffective. One possibility is non-Bayer sensors, which will affect color performance more than anything else. Another is further exploration of still-video hybrid cameras, where still performance is more or less what we have now, but video becomes an increasingly important part of the package. RED is beginning to take this route. A third option is smaller, lighter or cheaper cameras with the same image quality as the big models (although perhaps compromised in some other area of performance). There are other, more exotic possibilities, like a tiltable sensor (could add creative control over depth of field, but could only be focused by using Live View). Of course, the speed and performance of existing cameras could be increased - no law of physics prevents making a camera with the resolution of a D3x but the speed of a D3!
Which of these would you like to see? Does the camera you'd like to use for the next 5-10 years already exist? Do you own it, and if not, why not (too expensive? too heavy? wrong lens mount?)? If it doesn't exist, what could your favorite camera manufacturer give you that would cause you to use digital cameras like we all used to use film cameras - buy one to use until it breaks or wears out.
-Dan
Poll
14 (17.9%)
Author
Topic: Where to from here (what improvements in image quality do we need)? (Read 5771 times)
