Julio - Thanks, I thought Velvia felt thicker - I just never measured it. I once read that the original Tech Pan was on a .004" base - if true in LF that must have been a nightmare!
Julio - Thanks, I thought Velvia felt thicker - I just never measured it. I once read that the original Tech Pan was on a .004" base - if true in LF that must have been a nightmare!
My earlier post referring to a "plenum" should have said "septum" (confusing my phototography and audiophile terminolgy - sorry). Glad no one dinged me.
Wayne, If you want to have a real "nightmare" sometime, try cutting a small hole in the center of an unexposed sheet of 8x10 and loading it in a holder without the slide. Then, by looking at the hole and the surface of the holder directly underneath you can get some idea of how much the film separates from this "calibrated" plane when you do various things that simulate actual use, such as: letting it hang film-down for a few minutes or blowing hot breath on it (simulating the condensation that would occur when a cold holder is used in a hot bellows). Different films will react differently but I've seen film "pop" as much as .100". You can use the information gathered by this test to fudge your focus a little when you work in these problem situations.
I came upon some interesting data today. I was sent a very old wooden holder which contained two sheets of Ansco film. Behind each sheet was a black paper. I wondered (and still do) if the paper was for spacing or anti-halation.
Posting Permissions
Reply With Quote
Bookmarks