Jupiter-3 Won't Mount on Kiev 4x

[jmg1911]

After the original lens front element broke in two (don't ask), I ordered a Jupiter 3 from Fedka. It arrived in record time and looks marvelous, BUT.:bang:
I can't get it to mount.:bang: I put the tab over the red dot and turn counterclockwise, but the tab only just covers the screw head in that direction. It sems to just clear the screw head, so I think the lens is going into the mount far enough. I have put some considerable pressure on it, but no dice. The body is, I think, a Kiev 4a. The reason for the "I think" is it is rebadged to read "Contax." I bought it from Grizzly33Bear on*Bay and it is remarkably clean and functions well. It looks and acts as if it was entirely rebuilt. The original lens, which Grizzly said was a Jupiter8 goes on and off just fine.
BTW I know paying extra for the rebadging is silly, but I had a Contax back in the 50s. Nostalgia is a terrible thing.🙄

 

[Micky D]

Before mounting the lens, make sure the focussing wheel on the camera is all the way to the right and at infinity.

 

[jmg1911]

It is. It appears the bayonet is not quite aligned.

 

[Murray Kelly]

I just looked at the Kiev 4 and J3 here and I see what you mean about just clearig the screw. Never noticed it before. After that it rotates smoothly and locks, fine. You don't say if the lens turns any further after the screw head. The screw may be too proud to allow the lens to rotate. The tab is only to catch on the spring and lock. Conceivably the tab is too thick? Is the screw right in? Try it with it removed as a trial. Could be you need to polish a bit off the head with a whet stone.

Sometimes there are issues with the 3 cutout flanges immediately in front of the rear element. Mine is a '58 lens and unlike (say) J8s, these aren't machined all round, so as to give an adjustable 'prong', shall we say. Maybe yours is different and adjustable?

Another really odd problem I had was with Helios-103 lenses. One fitted both cameras - the other only one. Turned out someone had put a big blob of black matte paint just behind the mount in one camera and one lens fouled it when I tried to mount it. Judicious scraping fixed it. I was quite a while getting over that one. The other lens had a completely different diameter. No problem.

Let us know. It could be one of us next time!
Murray

After the original lens front element broke in two (don't ask), I ordered a Jupiter 3 from Fedka. It arrived in record time and looks marvelous, BUT.:bang:
I can't get it to mount.:bang: I put the tab over the red dot and turn counterclockwise, but the tab only just covers the screw head in that direction. It sems to just clear the screw head, so I think the lens is going into the mount far enough. I have put some considerable pressure on it, but no dice. The body is, I think, a Kiev 4a. The reason for the "I think" is it is rebadged to read "Contax." I bought it from Grizzly33Bear on*Bay and it is remarkably clean and functions well. It looks and acts as if it was entirely rebuilt. The original lens, which Grizzly said was a Jupiter8 goes on and off just fine.
BTW I know paying extra for the rebadging is silly, but I had a Contax back in the 50s. Nostalgia is a terrible thing.🙄

 

[jmg1911]

Murray, thanks for the tips. I tried them and gave up. Sent it to Fedka. If I learn anything, I will post it.