Confused! M39=L39=LSM=LTM?

Discussion in 'Leica and Rangefinders' started by syuji_honda, Apr 3, 2005.

  1. I bought a Jupiter-3 lens on ebay. I just find out it's a M39. Can
    I use the lens on my Bessa R3A with the M-Bayonett adopter ring?
    Some website describes M39 as different from Leica Screw Mount. Are
    they (M39, L39, LSM andLTM) all the same?
     
  2. You just need the screw-mount to M mount adapter ring, as you suggest.

    LSM=LTM. As to the M39 vs. L39, I'll defer to others, but I think that the L39 designation is the same as LSM/LTM and that M39 refers to the common enlarger lens specification used not just by Leitz but by just about every manufacturer of enlarging lenses.
     
  3. The Russian Zenit 1, 2, 3, and 3M cameras used a 39mm threaded lens mount, but insted of the 28.80mm lens-film registration distance of the Leica cameras, they use a (approximately) 45mm lens-film distance. Not clear if they really use the 39mm x 26 turns per inch Leica thread, or a conventional 39mm x 1mm pitch thread. This mount is commonly known as M39 or ZM39.

    At any rate, lenses for that camera will never focus directly on a Leica. They will also lack any moving cam on the rear of the lens to activate the rangefinder roller in the camera.

    But, so far as I can tell, the Jupiter-3 is not one of the lenses ever made for that camera. That's because the 50/1.5 Sonnar design requires the rear element to be too close to the film to use on an SLR.

    The Leica Thread Mount is known as LTM, LSM (Leica Screw Mount), and L39 (Leica 39). But it really shouldn't be called M39, since that really stands for Metric 39 threads, and the threads don't even use standard metric pitch.

    So, you need an M adapter. Any will do.
     
  4. awahlster

    awahlster Moderator

    To add M-39 is the common name for the 44.5 registration that the Braun Paxette and Dejur rangefinders use it is the same diameter and pitch as the Leica thread mount. It is also used on early Zenit SLR's. That said it is common for people to misuse this and have it refer to the 28.9mm Leica thread mount registration lens. With a Jupiter being Zenit lens I would worry that it was in fact an early Zenit SLR lens. Does the lens have a RF cam or the brass circular ring to operate the Rf coupleing do you have a photo that shows the rear of the lens?

    I collect Paxettes and Leicas so I have quite a bit of experaince with this confusion.
     
  5. What is this new thing ?
    - 39mm x 26 threads/inch
    - 39mm x 1mm pitch.

    Which one of these is the actual Leica Thread Mount? There is a minor difference between these two specs (26tpi = 0.9769 mm pitch), but I'm sure that difference is enough to screw up (well chosen pun, huh ?) the threads on both sides.
     
  6. I feel like I'm a little more confused. Anyway, if I use the M
    adapter, should I use the 50mm adapter to focus accurately or any M
    adapter will do it?
     
  7. Mr. Honda,

    TTBOMK, Leica has always used the 26 threads per inch as their pitch standard, not 1mm per thread.

    jerry
     
  8. awahlster

    awahlster Moderator

    A correction to my post where is wrote 28.9mm is should have read 28.8mm sorry

    Leica std screw mount is 39mm X 26T per 1" pitch with a 28.8mm registration (distance film surface to lens mount mating surface)

    The Braun Paxette M-39 mount is 39mm X 26T per 1" pitch with approx a 44.5mm registration (distance film surface to lens mount mating surface)


    Any one of my 2 dozen Braun Paxette lenses will screw on a Leica body it just won't focus correctly.
     
  9. Syuji,

    Any M adapter will work but obviously you should get the one that brings up the 50mm framelines. In the U.S., www.cameraquest.com is one convenient source for these adapters.

    I have several Russian lenses, including the Jupiter 3, and they all work just fine on my M cameras with the proper adapter installed.
     
  10. Rolf,

    How about the Jupiter-9 85mm? I have Bessa R3A.
     
  11. Leica's 39mm by 26 threads per inch was a deliberate curve-ball, to annoy those violating their patents and trying to make compatible lenses. Patents became moot in 1945.

    Canon's first LTM rangefinder cameras had a 39mm x 1mm thread, and they are not compatible. The threads seize up when you try and tighten them. They figured this out pretty soon. They switched the lens threads to toally LTM compatible. For a while, the cameras had a "slop" mount, where the threads could take either lens threading.
     
  12. Syuji,

    Some Jupiter 9's have focusing issues when used wide open at close to minimum focusing distance. Other than that, they work fine.

    One caveat: Many have congealed lubricants which makes them almost impossible to focus, so if you're considering one, make sure it focuses smoothly as this is an expensive repair. Again, be sure to get the M adapter that brings up the 90mm frames.
     
  13. Thanks Rolf, and everybody!
     
  14. So how can you identify a Russian ZM39 (Zenit Screw mount) from a L39 (Leica Screw Mount)? Is there way to know that a certain Jupiter is one or the other?
     
  15. It's not essential to get an adapter that activates the proper framelines. The Bessa
    framelines are user-selected, so that's not an issue. But you might as well do it anyway, in
    case you decide to use that lens on a different camera body in the future.
     

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