I have two Leicas with 5 cm, f 3.5 collapsible
Elmars. The older one is on a 1931 vintage
model C (1) which has been standardized and has the "O" st&ed on the lens mount flange.
This older Elmar has what appears to be a nickel
finish, and also appears not to be coated.
The later one is on a 1954 period iii f. It is coated, and the finish appears to be chrome
rather than nickel. Both lenses work exactly the same way of course, and aside from the slight
cosmetic differences already mentioned, are
I use them both regularly, the lenses and the cameras, and aside from the annoyance of reloading
at night, both are a pleasure to use.