RF Zeiss Jena Sonnar (red) T 85/2... question for fellow owners

[Brad Clemens]

Hello and thanks for reading.

I own a late post-war Contax RF Sonnar T 85/2 (15 blade aperture, optical blocks housed in brass, body's an aluminum alloy, blocked depth scale below the focusing ring, serial number puts it in the last production group before 1950). The lens functions as expected but I was unscrewing a filter today and noticed I was actually unscrewing the front optical block. I took it as an opportunity to clean the back of the block and the front of the rear block, but when I screwed the front block back in I realized it continues to rotate with pressure even after it's reached the end of the threads. It'll hold well enough for me to install a filter, but when I try to remove the filter, the block doesn't have enough tension to stay in place.

Has anyone else run into this (minor, since it doesn't affect performance and there's no chance of the block freeing itself) issue on this or a like lens? Did you bother to address it and, if so, how?

Thanks in advance.

Brad

 

[btaylor]

I have not worked on one of these lenses, but I recall from some repair chatter that this lens has some sort of a double helical focusing mount and it is not easy to reassemble properly. It sounds to me that this lens has been worked on previously and not reassembled quite right. It’s a classic design, I have 3 Nikkor versions as well as a couple of Jupiter 9’s- they all seem to be of nearly identical construction. The genuine Zeiss version you have is quite valuable, I think it would be worth having it looked at by a good repair person.

 

[guangong]

I have the Nikon clone made specifically for Contax. I agree with btaylor. Nowadays, this is of collector’s interest and well worth being properly restored.

 

[Brad Clemens]

I have not worked on one of these lenses, but I recall from some repair chatter that this lens has some sort of a double helical focusing mount and it is not easy to reassemble properly. It sounds to me that this lens has been worked on previously and not reassembled quite right. It’s a classic design, I have 3 Nikkor versions as well as a couple of Jupiter 9’s- they all seem to be of nearly identical construction. The genuine Zeiss version you have is quite valuable, I think it would be worth having it looked at by a good repair person.

I have the Nikon clone made specifically for Contax. I agree with btaylor. Nowadays, this is of collector’s interest and well worth being properly restored.

Thank you both. I thought it's the ZM that has the double helical focusing due to the floating elements and slightly closer MFD (one of the reasons they produced it in Germany instead of farming it out to Cosina) but I could be wrong. Any recommendations on on a repair facility for this type of lens?