A good article in sensiometry:
http://stephengrote.com/teaching/courses/files/storage/Zone%20System.pdfA simple trick what I am doing when
I have to develop a 135-36 film in different density:
e.g. the first part of the film was exposed normally and also developed for N=0.
The second part in
harsh light I over- exposed and want to shorten the developing time for -20%. (So N-1).
Working with any
range finder camera's like my Leica-M, Zorki, FED or whatever for type RF camera you have:
Transport one frame. Then pull off the lens. Put the timer on "B" and lock it so that the shutter is open. Then put a small self-adhesive sticker on the film surface. Close the shutter, put the lens on again and transport another blanc frame.
This second part of the 35mm film is done via N-1 exposure. When the film roll is finished you need two 35mm developing tanks.
The first part of the film in tanknr. 1. (N=0 development) When you feel the sticker when spooling into the reel you cut the film and
the second part you put in tanknr. 2. (N-1 development).
In this way it is possible to use a zone system in 35mm format. The overall quality of your negatives will be much better because on a 36 exposure film the chance that the whole film will be in approx. the same light contrast situation is normally not valid.
Theoretically you could do this with any 35mm camera however the chance on any SLR touching the mirror would not be a good idea but for any RF camera this system works fine.