I'm not sure that anyone has yet to actually design a camera around these small sensor sizes, though some seem to have been designed for full-frame 645, i.e. The sheer size of the cameras also tends to be overly large, given the smaller size of the sensors. So the precision required in the camera system is a huge issue and this includes not merely manufacturing precision, but also the things which allow the photographer to get a picture into focus in the first place, including the view through a viewfinder, the fineness of the focussing mechanism, the fineness of a tilt mechanism, where present, etc. The optical demands of 37 x 49 (or 36 x 48) mm sensors are vastly higher (four to six times higher in my estimation). Most of the existing cameras were designed for either 645 film or 56 x 84 mm (6x9) film. It's also true that the design properties of the cameras which can use the various medium-format and scanning back sensor options have, generally speaking, not fully caught up with the reality of the sensors. Those two things are what this article is largely about. The issues of optical defects in top brand (German) wide angle lenses and focus precision in digital back sensor calibration have unfortunately turned out to be huge. The issue of tilt focus capability is a large one for me, even considering the very useful focus blending techniques that are available. I first did what I could to evaluate all the most relevant properties of the various approaches, including the use of: scanning backs in view cameras, the new Seitz scanning back on an ALPA, the same on an ARCA R m3d, the new Seitz D3 pano camera, all four of the major brands of medium format backs at 33 or 39 million pixels, every medium format view camera, every 4x5 view camera, the Canon systems, all of the medium format SLRs, the other metal-plate type cameras (aside from the ALPA and the ARCA R), and the use of both single-frame shooting and multi-frame stitching methods with each of the above. I've been following this general topic closely since the mid-nineties and recently elected to make the switch from 4x5 color films to digital capture. I want to share the things I have been learning about high-end digital capture over the last year or two. My new rule of thumb: never assume a camera's focussing screen matches its sensor with respect to the focus adjustment (do a test right away), and especially never assume that a lens performs as it should, rather assume lots of variation from sample to sample of a given type, even with the products of the very best lens makers. Nor does this mean that the 35mm systems are without QC problems. I only bemoan the outsized "quality tax" on my main system's purchase.
I find it most useful to have both systems, as between them, they cover a very broad range of capabilities. I also use a full-frame 35 system, which fills a variety of different roles, and which also can be used for serious high res work, especially when using stitching. Supplementary article with comments on this one from other photographers posted here, April 20th, 2009.ĭespite the tale of woe for quality control which you will encounter in this long article, I want to make it perfectly clear that I find medium format digital capture systems to offer tremendous image quality and I rely primarily on my medium format system for my own work and am quite fond of it. Thanks are in order for Elmo Sapwater of and Michael Reichmann of įor providing the links to ensure that this article and the one which followed it a few days later would come to your attention. MEDIUM FORMAT DIGITAL CAMERA OPTICAL PRECISION Medium Format Digital Camera Optical Precision
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