Originally posted by 35mmfilmfan Looking at the mount itself (I presume - the black ring between camera and lens ?), it looks similar to a T2 mount (though obviously with thread differences, before I get jumped on [fun, but not in my state of health !]), and I think I can see a small grub screw just below the 5.6 aperture marking on the lens. If you slacken that off (and its corresponding brethren around the mount) you may be able to rotate the inner portion of the mount until the lens achieves proper alignment. Good luck, anyway.
That black ring is part of the separate M39/E-mount adapter. And, yes, the adapter's inner ring position can be adjusted by loosening three grub screws... however, the other lenses I own line up more-or-less correctly at its current position. Thanks for the idea, though
Originally posted by photoptimist A puzzler for sure!
Yet maybe someone did machine off 0.5 mm of the rear flange. To my eye it looks like there's a 1/2 mm of shiny ring near the mount surface which could be the residual tooling mark.
How is the lens in terms of focusing at infinity? Perhaps a 1/2 mm ring shim would fix it. Or you could get a second M39/E-mount adapter and machine off 1/2 mm from it. Either fix might also entail readjusting the focusing ring, infinity stop, or optical assembly to regain infinity-at-infinity focus. Or learn to hold the camera upside down -- LOL!
Good luck with this fun old lens!
Thanks
Re infinty focus, that's what really confuses me... It's absolutely spot on, with the hard stop at exactly the right point. So, if someone
has machined any material off the base, it must have been because the lens previously wouldn't reach infinity focus.
The more I look at photos of other Jupiter-3 lenses, the more I'm convinced this has had some material removed. There are tooling marks, and the back edges of the teeth should be slightly chamfered (like the front edges) - but they're not.
It's a minor issue, frankly. I didn't pay much for it (perhaps this is the reason!), the glass is immaculate, and it works perfectly; better than I'd hoped, in all honesty. Plus, if it really bothered me, I could simply buy another inexpensive M39/E-mount adapter and set the inner ring position specifically for this lens. So I have options... it's just a bit puzzling, is all
Originally posted by IgorZ I have one and it doesn't line up on my Zorki either. I just got into the rangefinders so don't quote me on this, but I think unlike Leica lenses which have to be put in in a certain way, Soviet lenses don't have a set position from which to start screwing them in. Because of that, the final position is a bit random. The last time I put it in it almost lined up, but still not at 12 o'clock.
Good to know - thanks
Perhaps that's the reason after all. I'm really not sure... My money's on some material having been removed, but then I don't understand why the lens wouldn't have reached infinity focus prior to this. Maybe when it was last serviced, the helicoids weren't put back together at the correct position and the owner chose to modify the mount rather than try the various helicoid positions... A strange choice, if that's the case, but I guess I'll never know for sure!