View Full Version : Rangefinder coupling
This may seem naive, but can one assume that the various lenses all couple correctly? I have a Zorki-1 (Industar-22) and a Zorki-4 (Jupiter-8). Can they safely interchange? I'm considering some further purchases of Zorkis.
No, it's not naive to ask because the answer is a definite "Maybe". If it were me, I'd measure flange-to-film plane distance on both cameras. IF they agree then I'd use ground glass taped to the film plane of the Zorki-4 to check the infinity focus of both. I'd also check the rangefinder infinity coincidence of both.
Some of the earliest Russian rangefinders in LTM were set to a different flange-to-film measurement than later cameras I believe but I'm not sure about the Zorki-1. It may have been made after a standard had been established.
No, it's not naive to ask because the answer is a definite "Maybe". If it were me, I'd measure flange-to-film plane distance on both cameras.
What's a good way to check this measurement? The only way I can think of is to use a depth micrometer, which isn't something everyone is likely to have around the house.
With shutter open and lens removed, I'd use a toothpick or something similar and rest the end of it against the pressure plate without applying pressure. Then I'd use a small sharp chisel laid flat against the lens flange to mark the toothpick. Repeat with the other camera and then measure to the bottom of the mark. You may not have a depth gage but you will need a slide micrometer or similarly accurate measuring device.
I think that if the infinity focus of the/a lens is correct on both cameras that should be a good indication of that the flange distance is the same on both cameras too.
Rick Oleson has a good page with instructions on how to test infinity focus:
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