Enlarger lens thread size

Discussion in 'Darkroom Developing and Printing' started by Stu, Sep 29, 2004.

  1. Stu

    Stu Guest

    I need to have a new lens board made for my Kodak Precision enlarger,
    to take an 80mm Componon-S lens. The board is 3mm thick and there is
    not enough thread sticking out the back to get a retaining ring on.
    I'm therefore thinking about getting a local engineering workshop to
    cut an appropriately sized hole in the board, and thread it. I
    understand the thread is 39mm diameter, but what about the thread
    pitch, tpi etc. What do I need to tell them?


    Stu, Sep 29, 2004
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  2. Stu

    Nick Zentena Guest


    Nick Zentena, Sep 29, 2004
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  3. Stu

    f/256 Guest

    It uses Leica thread M39 x 26Gg.60degrees
    f/256, Sep 29, 2004
  4. Assuming this is the same thread used on more recent enlargers, it's
    also the same as used on Leica Thread Mount (LTM) lenses -- and I'm sure
    I'll be corrected if this is incorrect, but I believe it's 1 mm thread
    pitch and a standard metric thread profile (60 degree, flat top and
    bottom). Take along the lens when you take the board in for machining,
    and the shop should be able to accurately measure the thread pitch in a
    minute or two. If they can't, you might consider having the work done
    somewhere else...

    I may be a scwewy wabbit, but I'm not going to Alcatwaz!
    -- E. J. Fudd, 1954

    Donald Qualls, aka The Silent Observer
    Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm
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    Opinions expressed are my own -- take them for what they're worth
    and don't expect them to be perfect.
    Donald Qualls, Sep 29, 2004
  5. The normal solution is to countersink the area around the hole so that
    the retaining ring can retain.

    This will be cheaper and more reliable than threading.

    Most enlarging lenses use the Leica Screw Mount thread: 39mm by
    26 threads/inch - not one of your common sizes.
    Nicholas O. Lindan, Sep 29, 2004
  6. Stu

    jjs Guest

    Nicholas' suggestion to have the board counter-sunk is the way to go (IMHO),
    if you have a machinist do the work. If you are determined to have the board
    threaded for the lens, bring the lens with you to the shop. What I fear is
    that they will compromise and use an existing thread set-up that's "really
    close" and mess you up.
    jjs, Sep 29, 2004
  7. Or alternatively, if the lens mount is LTM (Leica thread mount) as described
    above, then you can do as I did and use the lens mount from a SovCam--any of
    the Soviet Leica copies (Zorki & FED). Since I work on these old cameras, I
    happened to have a spare lens mount, which has 4 mounting holes to easily
    attach to a flat lensboard. You can probably obtain one of these from other
    SovCam tinkerers or from one of the folks who repair them.
    David Nebenzahl, Sep 29, 2004
  8. Stu

    Stu Guest


    Thanks for all your replies. I think I'll go the counter-sink way. It
    should be cheaper too!

    Stu, Sep 30, 2004
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