That was what I thought, but I always wondered also about using a medium format digital back for large format, how does that translate?
Thanks again!
Well there are several points about your query.
First it works to use a DB on a LF camera if it is precise enough.
To begin with Digital requires at least 4 times more precision in focus than film ever will. And with the higher mp digital backs, perhap 5 or 6 times more precision for really sharp images.
So most Anologue(film designed) lenses need not apply. The ones that come closest are the Apo-Sironar
S from Rodenstock, especially the 135mm and 150mm, and the 55mm Apo-Grandagon, also from Rodenstock. The 72mm Schneider XL also has some traction. But the rest of the analogues need not apply. The digital designs will far out show the rest and even these lenses in all aspects except coverage. Even these analogue lenses require much more sharpening and or contrast adjustment than their digital focal length equivilants. So if purchasing a new lens for digital LF work buy the new digital design if at all possible.
Before moving on to other points on lenses, let me say it is extremely difficult to focus on a ground glass precisely and, especially, wide angle lenses in the focal lengths required for a MF DB, ie 28mm, 35mm, 40mm, 43mm, etc. I have seen few people who could get 3 out of 5 tries accurate, with wide angles. With film lenses and 4x5 format much easier except they will note easiest with normal to long lenses being easiest to focus.
The curvature of field being more severe, the shorter the focal length of the lens, and the fact that in digital for sharpest images, F11 is your best stop in MF to cover the focus shift, which all lenses exhibit more or less, are all factors in this focusing problem.
Next camera bodies. Wood is OK but not nearly as precision as a metal body. Even these are not all created equal. Currently the best of the traditional view camera designs for use with digital are Arca-Swiss, Linhof and Sinar P/X models.
Arca-Swiss and Alpa, and Cambo also produce 'Technical cameras', which incorporate extreme precision and the movements of a view camera into a bellowless body. They can all be focused without a groundglass for more precison, especially the Arca-Swiss which has the finest focus pitch currently produced.
Lens wise for these backs, the rules outlined above for focal length choice still apply. For most of the backs available, 70-80mm is normal, and shorter are wider and longer focal lengths are telephoto.
Hope this helps with some decisions. Schneider has a great article on their website or at rodklukas.com called 'Why shoot Digitar' which explains in great detail, but clearly, why the digital lenses are superior to analogue lenses when crossing over to digital.
Hope this helps,
Rod