I have a 90/4 Elmar Screwmount lens with some problems with the glass but the barrel is in excellent mechanical and cosmetic condition. Can I purchase a M series version of this lens which I believe was made until the early 60's with a pretty good reputation and just exchange the lens assembly?

-- Gerald Widen (gerald@sfa1.com), May 08, 2001

Answers

There were 2 versions of this lens, 4 element and 3 element, both made in LTM and M versions. The more common 4 element version went through a few different mount changes in its run, some minor and some major. The last versions were E39, the immediate predecessors E36 (both with silver mounts with Vulcanite trim)and I know from personal experience there were at least two different cosmetics for the chrome/Vulcanite E36 model and I tried to play swap-out with them for much the same reason as you, and was unsuccessful as the lens heads themselves were threaded differently. So to answer your question, "maybe". In any case, if you found 2 samples of identical mounts, you might still have a problem requiring recollimation by a repair facility to ensure correct focus. Yes, the M and LTM mounts should be set to compensate for the differing respective body-to-film distances, but all those early Leica lenses (and some later ones) were individually collimated to adjust for manufacturing tolerances.

-- Jay (infinitydt@aol.com), May 08, 2001.