J3 optical unit interchangeability

[snapper78]

Perhaps a silly question, but can one take the optical unit from one J3 and put it into another J3 mount without running into serious problems. Obviously it is possible, but is it advisable, say if one mount is less stiff than the other or one optical unit clearly superior?

 

[Dez]

Yes, but you will need to make shims to fit the optical unit to the mount. There is a lot of variation, and they need to be individually fitted.

Cheers,
Dez

 

[xayraa33]

It might not matter in your case but:

The very late made black J-3 lenses have the back section block elements cemented and not held in by a threaded ring keeper.

So not all J-3s are constructed the same way throughout their entire production run.

 

[snapper78]

Mine are fairly early models, serial Nos 5105711 and 6007195.

 

[Filzkoeter]

The 51-one should have Zeiss glass. According to the master of Sonnar lenses, Brian Sweeney, the KMZ ones from 51 - 56 are optically the best, followed by the ZOMZ ones from 58 - early 60s.

You can also clean and relube the mount if it's stiff. Sonnars and their soviet counterparts are really simple lenses to work on. It's important to mark the point where the helicals come apart, you have to find the exact same spot when you are reassembling them or the lens will be off.

Some resources:
http://aperturepriority.co.nz/50mm-jupiter-3-f1-5-information/

 

[snapper78]

Thank you. That looks like very useful information.