[Leica] Interesting problems with M39-Leica M adapter

[martin at jangowski.de (Martin Jangowski)]

Hi folks,

I recently bought a CV adapter ring M39-Leica M. The seller said it was 
unuseable and sold it cheap. I couldn't think why something simple like a 
adapter ring wouldn't work and bought it.

Unfortunately, he was right. It really doesn't work... it can't be turned 
far enough in the camera bayonet. There is about 10deg rotation missing, 
it just stops and can't turned further.

I examined the lugs and saw that the ring (a 28/90 version) had some tool 
marks at the lug that moves the finder masks. Obviously, someone tried to 
convert this ring from 28/90 to 50/75 or 35/135 by removing material from 
this lug. There was some wear at the lugs, but nothing like the smoothly 
working bayonet of my 1964 Elmarit 90mm... that one looks bad, but works 
like a charm. The CV ring doesn't have any dents or obvious damages, only 
the lug for the finder has a filed front edge.

When turning the lens, the bayonet lugs move under the slopes of the flat 
springs under the camera lugs. The lens is held against the bearing 
surface of the camera by these springs. Is it possible that the filed 
off lug doesn't glide correctly under the spring but catches it with its 
damaged edge?

Unfortunately, it's impossible to see the movements of the various parts. 
Does anyone have an idea if its possible to repair this ring?

Gr??e aus Hohenlohe,

        Martin Jangowski

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