Mamiya 7II: Dropped Camera, Stuck Rangefinder and Flange Check
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya 7II outfit came in for examination after being dropped. The immediate symptom was that the rangefinder would not move. And the 80mm lens was not focusing properly. After some initial examination, I found that the rangefinder arm that contacts the lens cam would only move slightly.
While all cameras don’t need this sort of test, with impact damage I check lens flange to body distance. As shown in photo two, the camera is put onto a parallel block that fits into the film plane and a fixture is installed in the lens mount. After calibration of the correct distance on the indicator gauge, the gauge is applied to the top of the lens mount fixture as shown in photo two. In this case, all was within specs since the distance was (-0.03mm) and specifications are (-0.04mm - +0.00mm).
I was recently asked why the specs would be different for (-) and (+) distances. Reason is that the correct distance on the Mamiya 7 for lens flange to body is 57.35mm (-0.04mm). This is the distance from the lens flange to the outer film rail. So, if the lens flange is off in the minus direction, the image will still be on the film due to film thickness and some possible buckling of the film. If off in the positive direction, the image would be focused on the pressure plate and that would be less useful.
In the case of this camera body, the rangefinder itself was damaged from the impact. While Mamiya did not sell individual parts for the rangefinders on their cameras, I have a small supply of parts from cameras that gave up their life so others may live.
The final photo shows the rangefinder being removed and visible is the electronic shutter speed indicator just to the left of the circuit board on the body.
