Jupiter 8 m39 Rangefinder lens off horizontal alignment (the only lens)

[Ejg1890]

I have both a Fed 2 and Zorki 3 FSU rangefinders and a few m39 mount lenses, all recently acquired. I noticed yesterday the Jupiter 8 is very slightly out of horizontal alignment on the Fed 2, but my Industar 22 that came with the Fed 2 is in horizontal alignment. I haven’t seen this with any of my Leica M mount lenses with the Leica camera. Why would one be out of horizontal alignment but the other not? The only fix I know is on the camera but would impact all lenses. Thanks.

 

[joe bosak]

If they differ in horizontal alignment... could mean that they focus at different points so whereas one shows coincident images when the lens shows say 3m, the other at 3m gives RF images slightly out of line? Maybe they have been shimmed to different cameras. So - same reason that Russian L39 lenses don't focus right on Leicas (sometimes).
Otherwise... helical tolerances perhaps.

 

[Sonnar Brian]

Does the lens focus in front of what the rangefinder indicates, or behind it?

 

[Ejg1890]

Does the lens focus in front of what the rangefinder indicates, or behind it?

I’m not really sure what you mean? I select something that should be at infinity focus. I rotate the focus knob but the lens turns all the to the end. At this point the “ghost” image has not reached the actual image. So, in guessing what you’re asking the lens is gone as far as it can before aligning.

 

[Sonnar Brian]

The RF Cam need to be extended to drive the RF to infinity as the lens is at infinity.
I use Copper Tape on the RF Cam of the lens.
First- test if actual focus agrees with the rangefinder. If it does, you will need to adjust the RF Cam and the Shim for both to agree.