Leica Sonnar 50 1.5 LTM Questions


New Member
Hello! New to this forum, but not to camera/lens work.

I have recently acquired a 50/1.5 Sonnar in Leica screw mount, pictured on the left. Unfortunately, it came with some rangefinder cam issues and doesn't accurately couple; it will focus to infinity but the coupling does not quite reach that far. Any information about taking the focusing mount for this lens apart would be appreciated so as not to damage it-- I've serviced all my own lenses, including several Jupiters, but the mount of the Sonnar is somewhat confusing. Are there set screws where the optical module threads into the body?
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Brian-Sonnar should answer.
But while I'm looking at it, yes, I 'serviced' my own J-3-LTM. It aledgedly is not that hard, there are on-line manuals.
I used my own 'markings' at disassembly.
1) I also cleaned up the helicoid through which the lens is mounted in the house. I noted that there was some hard residue from hardened grease. When I remounted, the lens was much better in focus than before. I guess that the grease there had made a little layer that knocked off the assembly by just a little.
2) then I made errors. Serependipity to come! There is a bottom (closer to mount) ring that can be positioned in two places, each 180 degress apart. Lo and behold, that difference is just the 0,1 mm or what ever it is, between the two 'standards' of flange distance, the Jupiter standard and the Leitz standard. At least, that is what I found out. So in Live view (EVF Leica M240) I would get the same focus point as with the RF cam!. Also at 1 meter!
3) if you 'turn that spacer ring' then all alignments are off in the lens once assembled - the aperture ring has its own position, the focus too.
Aesthetically I thought it 'stupid' and I sold mine again. I bought a J-3 head and an adapter.
I am sorry to this day I sold my J-3 LTM. That J-3 lens was a marvel.

I'll be going to an 'exhibition' today of my work:
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If you type "ltm sonnar" into the search feature of this forum there is quite a bit of stuff on these lenses. The one I have here I just sent out to Henry Scherer and he cleaned it and adjusted it etc. as I did not feel like messing around with it myself. I have a second one that is an f2.0 collapsible model and I was thinking of taking that one apart and trying to clean it up.
Thank you both for the replies. BenG -- I found some stuff on the LTM sonnars, but I don't think anything that quite covers disassembly of this body type. I'll try searching again to make sure, though.

Thank you for your remarks, Albert. I believe the J-3 is a much easier lens to service because the ring with the focus scale pulls off from the front after its set screws are removed. I've worked on mine, too, and it's a marvellous lens -- I'd personally consider the mount an upgrade over the Zeiss type. I'm sorry to hear you regret selling it -- it sounds like things really worked out well during the disassembly.
Congratulations on your exhibition!