Rb67 65mm c lens floating element ring stuck

Discussion in 'Medium Format Cameras and Accessories' started by heespharm, Jan 14, 2011.

  1. heespharm

    heespharm Member

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    Should this be free turning... Is there a reason it would be stuck in one position??? Can this be self fixed??
     
  2. Neil Grant

    Neil Grant Member

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    It's normal for the floating ring to be moderately stiff. Some lens's helicoids seize up over time (eg 55mm f/2.8 Micro Nikkor) but the RB C-lenses with floating elements aren't prone to this. Maybe something has broken off inside.
     
  3. hpulley

    hpulley Member

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    Which ring is stuck??? There is no focusing element on RB67 lenses, the body focuses using a bellows instead so the lens can only change its aperture and shutter speed, and there is a stop down slider. Mine is the older pre-C version; did they add another ring?

    My 90mm f/3.8 C lens is the same except it has the manual distance/DOF scale too (you have to look up the distance and set it yourself as there is no coupling with the body bellows focus).
     
  4. CGW

    CGW Member

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    Get a 65mm and you'll see the problem. The "extra" ring should move. More info here:

    http://photo.net/medium-format-photography-forum/009mzN
     
  5. hpulley

    hpulley Member

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    I do have a 65mm but not the C version. I guess they changed it. My Mamiya Sekor 65mm doesn't have a distance ring on it like my other Mamiya Sekor lenses.

    I guess I have an older version without a floating element. Sorry, I thought it might be the same. I have noticed some odd stuff when using it as a macro but I thought it was just due to the narrow DOF:
    [​IMG]
    Little brown mushrooms edit by Harry Pulley, on Flickr
     
    Last edited by a moderator: Jan 14, 2011
  6. CGW

    CGW Member

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    Yup, the "bonus" ring was a late model feature that carried over to some of the KL lenses.
     
  7. hpulley

    hpulley Member

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    Sounds like the simpler, earlier design may be a safer bet for 30-40 year old lenses. I bet most owners don't realize they need to turn it so it probably gets seized up.
     
  8. fmajor

    fmajor Member

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    I notice my fine-tune "focus/floating element" adjustment ring is stiff as well. I'm making sure to turn it regularly to ensure it remains that way until i've some CLA funds set aside to have any short-comings brought back to spec.
     
  9. fmajor

    fmajor Member

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    I forgot to add that i have the "C" version 65mm lens.