Hi, I have recently purchased a 150mm Xenotar 2.8 for my Chamonix 45N-1 and was just wondering what the relationship is between the film being held perfectly flat in the dark slide and shooting wider open than f5.6? So after some tests, I have had great difficulty in getting really sharp pictures ( portraits ) at f2.8, f3.5 and even f4, as the depth of field is really limited. This is basically the whole reason I bought this lens, to have a very sharp drop of focus. The original screen that was provided with the Chamonix ( a fresnel type arrangement ) was absolutely hopeless and would pull focus a half foot/foot in front of the what was focused on the groundglass. When I contacted Hugo about this, he said that was a problem with those fresnel type screens and shooting really wide open. He then sent me a "normal" groundglass which really seemed to fix the problem... That is with stationary objects mind you. I recently had a friend enquire about a Maxwell screen for this camera and Bill Maxwell wrote back sayingthat his screen would help with this problem but there was still the concern of the piece of film in the darkslide moving around and there being a tolerance of plus/minus 0.25 mm mm for it to affect sharpness. Apparently his screens are meant to be excellent ( although they cost about half as much as the whole camera ) but I was just wondering if someone could explain how stopping down helps this problem? I would have thought that if the film wasout of the "plus/minus 0.25 mm" range , then it would be affected regardless of what aperture was used to take the shot. Any insights would be greatly appreciated. Kind Regards Josh
Bookmarks