Jupiter and Industar focusing

[geoagros]

Hi guys,

So this one goes like this,

I've got an Industar 61, a Jupiter 8 and a Jupiter 12 to use with a Zorki 4.
I was trying to adjust the rangefinder but I can't get it right... All the lens register differently... Not by much, but the 1 meter mark in the industar 61 is @ f2.8....

I know that the lens are focusing according to scale, I've tester with a ground glass.
I also know that the cam throw is pretty much the same in the 3 lenses...

But then, there are differences in the rangefinder patch @ 1 meter and @ infinity! I'm confused about this one...

Any light you could shed about the subject?

Many thanks!
Regards!!

 

[wolves3012]

It isn't unusual for different lenses to produce slight differences in the scale reading when aimed at the same target but they should be quite small. If the errors aren't small, it's likely at least one of the lenses is the cause of the problem. This, of course, assumes the RF is calibrated correctly. Take a look at the sticky, in this sub-forum, that explains how to adjust your RF. You would be best advised to use a 50mm lens for calibration, since they are the least likely to have been messed up by any repair work - so the I-61 or J-8 rather than the J-12.