Thread size & pitch of pre-war Bessa 6x9 RF (w/ Skopar)

Discussion in 'Medium Format Cameras and Accessories' started by Loris Medici, Dec 15, 2010.

  1. Loris Medici

    Loris Medici Member

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    Hi all,

    What is the exact size (and pitch) of the threads in front of the Skopar lens of pre-war Bessa 6x9 RF?

    TIA,
    Loris.
     
  2. Jojje

    Jojje Member

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    If nobody has a correct answer you may have to use a thread pitch gauge to find out. (Maybe borrow from a machine shop..)
    These inside threads can be tricky to measure.
    (I once machined with trial-and-error method a metal lens hood to my Mamiya-Sekor (1959) with a lathe and had to make a tool for it. If my memory serves me right this M40.5 thread had a pitch of 0.75mm and had an angle of 50 degrees.)
    Have a look at these: http://www.gewinde-normen.de/en/camera-mount.html

    I found it! Mr Butkus's manual says "37mm"
    Have a go: http://www.butkus.org/chinon/voigtlander_pdf/voigtlander_pdf_manuals.htm
     

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    Last edited by a moderator: Dec 15, 2010
  3. edp

    edp Member

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    37mm push-on, not screw-on.
     
  4. Jojje

    Jojje Member

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    I knew it. Sounded too easy...
     
  5. Loris Medici

    Loris Medici Member

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    Thanks all, I'm aware about the 37mm push-on. I noticed there are threads in the inner side of the filter ring, I was planning to use a step-up ring (there are shops producing step-up rings for odd sized filter threads) to a more usual filter size (39mm for instance) and use accessories (a lens hood - most importantly!) designed for it.