Chris Patti , May 29, 1998; 12:54 p.m.
When people talk about "loss" of depth of field in MF compared to 35mm, they are referring to comparisons between lenses with similar angles of view, not similar focal lenths. It is true that a 45mm lens with have the same depth of field whether used on a 6x7 camera or a 35mm, but that is an irrelevant comparison since, on a 35mm it is a nearly "normal" lens while on 6x7 it is a wide angle. The 45mm wide angle (on 6x7) has substantially less DOF than a 24mm on 35mm, which has a similar angle of view. When you move from 35mm to medium format, as a practical matter, you do, indeed, "lose" substantial depth of field at comparable fields of view.