I used to have a copy or link to Zeiss Camera Lens News No. 10, but can't find it any longer. Anyone have this PDF?
I'm interested in a hard copy of the information that is paraphrased below:
(in
Camera Lens News No. 10) the bulge increases with time after winding medium format film: it's small at 5 minutes, significant at 15 minutes and maximum after 2 hours. One solid piece of useful information from Zeiss: the bulge is only half as much for 220 film as it is for 120. The Zeiss rule of thumb is, " For best sharpness in medium format, prefer 220 type roll film and run it through the camera rather quickly." Temperature and humidity probably also affect flatness.
I had may issues with film bulge in the 1980s. In fact I even recall a "Medium Format Guide" recommending to focus in front of the nose on portriats. I have done my own studies on various films and various roll-film cameras and backs in the 1980s but recently, at least for me, the issue (of film bulge) has not presented itself in my images like it used to. I was going through the list of reasons why below and wondered how the lack of film flatness is affecting other these days. For example, I don't recall anyone commenting on the ability or lack of ability of the Shanghai 220 film to lay flat.
1) I got rid of my SLX which was a bad offender; replaced with 6000 series and Hy6 which tend to stretch the film across the film gate.
2) Film base and or paper may have changed since the 1980s
3) My photography habits may have changed (using film slower/faster) and or more or less outdoor cold-weather photography.