I believe the question of film flatness in 6X9 format can be a problem even with best modern cameras, including the Fuji 6X9 rangefinders. Over the years I have done a number of resolution tests of 6X9 cameras, including the Zeiss Super Ikonta C, Moscow 4, Moscow 5, and Fuji GW690II and GSW690III. What I have found is that it is quite difficult to to get consistent results from one testing session to the other.
One problem, of course, is that we tend to use the resolution charts at a distance of 10X-20X the long focal length of these lens, and focusing at close distance, severely stretches the limites of rangefinder focusing with lenses of 100mm and more. However, I believe that the film flatness issue David mentions is as great a problem in obtaining consistent results with 6X9 cameras as the focusing ability.
On the whole I find that in order to get the kind of quality I expect from a 6X9 format folding camera it is necessary to avoid subjects closer than about 8-10 feet, and to always use the camera at as high an aperture as practical, say f/16 to f/32. What you need is to get as much depth of field as possible to make up for the lack of flatness at the film plane and for the relative lack of precisioin in the rangefinder focusing system. With cameras of this type diffraction is less of a problem than depth of field.
Although I have never worked with a Bessa II, and I understand that in the world of 6X9 folders it is considered the creme de la creme, I suspect that some of the issues relating to rangefinder focus and film flatness still apply, since they also apply to some extent with the modern Fuji rangefinders of this size.
Originally Posted by David A. Goldfarb
Last edited by sanking; 03-16-2006 at 12:41 PM. Click to view previous post history.