Jupiter-12 Contax II compatibility issue

[bmcnew]

My first post on this forum:
I have a Jupiter R-12 serial beginning 84... in Kiev/Contax mount that doesn't seem to fit my Contax II. The outside diameter of the mount measures 55.55mm which is too much for the throw of the release nipple on the infinity lock. A Zeiss Contax mount on a 13.5cm lens measures slightly less than 55mm. Has anyone run across this problem?

[Brian]

Yes, I have. Two causes possible:
1) one of the flanges on the bayonet could have been bent. I had one like that, had to bend it back into position.

2) The tolerances on the J-12 and other Russian lenses were sloppy. I've filed down a couple of them to fit. If you can, create a gallery with some pictures of the lens.

[japomono]

Are you sure you have a pre-war Contax II and not a post-war IIa ?

The latter does not accomodate the J-12 anymore, because the inner housing is somewhat smaller the the old model.

[bmcnew]

Thanks for the response. I will try to get some photos posted. The camera is definitely a prewar model II, the lens was purchased on ebay. If the problem is tolerances, perhaps a little tight on the German side and loose on the Soviet, I am comfortable with grinding or filing the lens to fit. Worst case - send away for another $40 Jupiter.

[bmcnew]

Brian,
Hopefully I have attached photos.
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[Brian]

It's probably one of the flanges of the bayonet holding things up. The chrome collar that goes over them has alsao given me problems. Prevented the lens from being pushed back far enough to turn the lens. For the latter, it is held in by the visible set screws. I removed it and filed it down a bit. It's annoying, but the you can usually see the part that is hanging up. Then, file and grind.

[japomono]

So do I understand correctly that, possibly with some work, one can fit J-12 on post-war west Conatax's (IIa and IIIA) ?

If not, what about the post-war Iena Contax mount Biogons ?

In other words, what are the wide angle affordable options for the IIA and IIIa ?

Thanks in advance,

Benjamin

[bmcnew]

I removed the chrome collar at the base of the lens and used a grinder to remove ~2mm from the bottom edge where it sweeps past the infinity lock post when installing the lens on the camera. The J-12 now installs easily. It turns out that the problem was with my Contax II, the J-12 had no problem with a different Contax II body I gained access to. I still have to test with film to see if the camera and lens are a good match.
I should point out again that this camera is the pre-war Contax II and the project does not address the compatibility issues with the Contax IIa and the Jupiter-12.

[Brian]

I do not believe it is possible to fit a J-12 to a Contax IIa or a IIIa. I've never read of anyone doing this, and think the rear element sticks back too far. It will got a Nikon RF, and the Contax II and III.

For a cheap wide-angle for the Contax IIIa- look for a Nikon 3.5cm F2.5 in user condition, should run ~$200 or so.

[maltfoto]

If you can find a Bessa 35mm F2.8 color-skopar in the old Contax Mount, that will work too. I have seen them on ebay from time to time- Kievman

[disneytoy]

That's a nice looking lens!