Mamiya 7 7ii Testing Rangefinder Accuracy

[bwcolor]

I want to test my two bodies for Rangefinder accuracy. Since the back focus of each lens should be identical by design, I'm guessing that I should test only my longest lens wide open on both bodies. Is there a particular distance at which I should test? Is my method correct, or should I be testing multiple lenses on both bodies?

 

[qruyk12]

i would test at infinity with multiple lenses. sometimes a lens is out of whack and the camera is fine.

techs actually use a jig to test and calibrate. At least the ones that know what they are doing.

 

[john_s]

Although long lenses are the the most critical to focus, it is actually wider lenses that are the toughest test for a rangefinder system. Definitely test with multiple lenses.

I would guess that the lenses would be right at their infinity stops. I would pick a distance that you might use a lot. I use 2.5m for my tests. I think that Leica's standard method is to use infinity plus two distances but i can't remember which ones.

 

[bwcolor]

Thanks for the responses. It seems to me that since the adjustment is a single screw on the body, that one should be able to pick any distance. If the lens proves to be out of focus at another distance, then there must be something wrong with the lens. I'll test each lens on each body at three distances. That should be enough to really confuse me. It will also help me to determine framing accuracy.

 

[john_s]

Thanks for the responses. It seems to me that since the adjustment is a single screw on the body, that one should be able to pick any distance.......

I've wondered about this. The Leica has two adjustments, one like that in the Mamiya, and another that effectively adjusts the length of the cam follower. I don't know about the other makes such as Zeiss and Voigtlander but I think they might all be a single adjustment. (Not including the vertical alignment, of course) Correct me if I'm wrong please.

It is, of course, absolutely critical in the Leica if using f1.4 or even f1 lenses. For MF, apertures are smaller, especially the Mamiya 6 and 7 where it's only f3.5 or f4.