I recall a note on a data sheet from the mid 70s that metioned that they expected that 35mm would be printed with a condensor enlarger, and sheet and 120 would be printed with a difusion enlarger. thus different aim Gamma required.
I develop my HP5 35mm quite a bit less than 120. About 25%. I’m using ID-11 1:1.
The film bases for 35mm, 120 and 4"x5" differ in thickness as well as the emulsion thicknesses which drive the different development times.
But I find the same contrast index for same film different formats
I take it that the 25% makes them look the same and under a densitometer they measure the same?
Ilford gives the same time for ID 11 1+1 in 120 . What does Kodak give for D76?
Have you ever used the same time for both to see what difference this made v 25% less?
Thanks
pentaxuser
What I mean is that I find, for TMY2, at 13:30 reaches 0.62 CI in D-76 1:1 at 20-degrees C whether it’s 35mm, 120 or 4x5 so different development times for different formats are not justified on the basis of the same aim contrast.Yes, that is so. In the end, the films are developed to the same contrast, as a standard. Once a starting place is established, one can wander anywhere.
Film base plus fog can vary depending on the format size, even between films of the same name by the same manufacturer.
Fred Picker used to teach that a personal film speed should be determined by testing for each size of a type of film. I have found different film base plus fog for 35mm vs 120 Hp5 and it was true for TriX when 35mm was compared to 4x5. I no longer use TriX ...... beyond my budget now.
Well Bill, it would seem that if your experience is atypical then it is atypical for the film makers as wellUnless someone else has different development contrast for the same times, and my experience is atypical
I don’t have a densitometer. I look at contact sheets and prints made at grade 2 or 2 1/2. If I develop my 35mm HP5 for the same time as my 120 HP5 they are overdeveloped.
It sound like you got me wrong, my comment wasn’t clear.Well Bill, it would seem that if your experience is atypical then it is atypical for the film makers as well
pentaxuser
film makers such as Ilford who generally quote the same time be it 35mm or 120
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