Hello,
For me, this lens has nothing to do with the Russians.
It was made in the west, and has a mount that I have never seen on wartime lenses, or even on postwar modified by the Russians.
The weight too is totally different: 226g against 120 to 150g.
As for the optical part, many of these early postwar "westie" lenses have separation problems. Certainly a question of glue. It is perhaps why CZJ continue to deliver Sonnars for the Contax IIa up to 1950/51.
Jacques.
Well.
This is with no doubt a late Carl Zeiss (Oberkochen made : West Germany) Sonnar 50/1.5 in Contax RF mount removed off its original barrel then installed in a custom made LTM barrel. Very likely a one-shot home made machinist job. Looks good BTW.
The bump on the lens black nose isn't a problem, the nose is reversible and symmetric so it won't be difficult to make the lens look better.
What you write about the early Western Germany made Sonnars is not correct.
The early Western Germany made Sonnars were named Zeiss Opton.
CZJ delivered Sonnars for the first Contax IIa in 1950/1951 because the Oberkochen lenses plant wasn't running well enough so that lenses could be produced there yet.
At that time, nobody in Jena could know that the Oberkochen plant ingeneers would experiment epoxy cement instead of Canada balsam on their late production run Sonnars, ten years later.
The separation problems occur on the very late Western Germany lenses, i.e., lenses named "Carl Zeiss" and not "Zeiss Opton" any longer.
This one belongs to the club so at the end of the day the best thing is to stay away from it.
All the stuff written by the seller about that lens picked up in Germany at the end of the WWII is pure crap.