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     John_shriver Tinkerer Username: John_shriver Post Number: 28 Registered: 12-2006 Rating: N/A |
It really takes a bunch of precise jigs to calibrate up Leica rangefinder lenses and cameras. Cook and Perkins made a very nice ground glass that screws onto the rear of an LTM lens, and holds the ground glass the correct 28.80mm from the lens flange. Hard to find, and pricey if anyone else knows what it is. Then there are reference dummy lenses, which have a rangefinder cam protruding a calibrated amount. Canon specified using one that was set at infinity, cam 7.5mm from the lens flange. Measuring the flange to film distance on the camera is tricky. You can use a dial depth gauge. Or Canon specified inserting a 28.80mm thick block, and measuring that it it flat with the lens flange. Realize that the lens flange has to be collimated not only to be the right distance, but to be parallel to the film. I'm perfectly happy to replace the shutter curtains in an LTM camera, and adjust the shutter speed. But I leave this sort of work to the pros with the right equipment. Yes, Tomosy says how to use a Focaslide as a substitute for that Cook and Perkins device. But his method assumes you know the exact focal length of your lens, which you may or may not know. (This is because you're not collimating at infinity with the Focaslide.) |