OK, Thinking caps on...!

Discussion in 'Accessories' started by Dave in Wales, Mar 6, 2015.

  1. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    There ought to be enough accumulative photographic knowledge amongst members of this esteemed forum to solve my problem.
    Well, hare's hoping anyway.

    Problem...To fit a Canon FD lens onto a bellows that has a Pentax M42 x 1 female thread.
    The manual aperture ring on the lens must function but data is not fed to the M42 thread.

    The obvious answer is to use a FD to M42 adaptor.....very difficult.
    According to the Pentax forum such an adaptor has never been commercially produced, if my memory serves, it's to do with the back-focus or some such.

    A few special adaptors may have been made to order by someone like Novaflex.

    I have done it on paper using four items, but it is far from ideal. I have used two adaptors, a step-up ring and a male to male coupler.
    The step-up ring is M42 x 1 and one of the adaptors is M42 x 0.75, they 'would' fit together with effort, but as I said 'far from ideal'

    If you offer any solutions can I please ask that the adaptors are 'available' not theoretical, and not from ebay.
    Last edited: Mar 6, 2015
  2. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Real Name:
    This begs the question: wouldn't it be a LOT simpler just to either use an M42 lens or to acquire an Canon FD bellows? Seems like that would be a lot simpler (and potentially cheaper) than cobbling together a Rube Goldberg solution.

    It makes sense to me that a commercial CanonFD-to-Pentax M42 adapter is available since Canon FD has a shorter lens register than M42 focus in normal operation would be difficult to achieve. Obviously for macro use, that's not necessarily an issue, but that's the reason such a beast is going to be difficult to find.
  3. barry13

    barry13 Super Moderator

    Mar 7, 2014
    Southern California
    Real Name:
    Someone's been posting this week about using 3-D CAD software to merge 2 adapters together and 3-D print them.
    (sorry it's theoretical, but should be practical.)

    However, I don't know enough about the FD aperture control to say what is needed for that.

    • Like Like x 1
  4. davidzvi

    davidzvi Mu-43 All-Pro

    Aug 12, 2012
    Outside Boston MA
    Real Name:
    OK, 3D printing custom adapters? That would just SO WAY COOL.
    • Agree Agree x 1
  5. listers_nz

    listers_nz Mu-43 Veteran

    Nov 22, 2013
    Christchurch, New Zealand
    Real Name:
  6. davidzvi

    davidzvi Mu-43 All-Pro

    Aug 12, 2012
    Outside Boston MA
    Real Name:
    Just thought of another really cool 3D printer item that would be cool.

    Custom extension tubes + adapter.
  7. TNcasual

    TNcasual Mu-43 All-Pro

    Dec 2, 2014
    Knoxville, TN
    I'm the one that is getting a 3d printed custom adapter. I developed a model for Agfa Ambi Silette lenses to mft. It really didn't take very long to create the model. I found on the Thingiverse website an Ambi Silette to Leica mount and a Pentax k to mft adapter. Using the free, browser based site Tinkercad I was able to lop off the unneeded ends and combine the pieces to make my adapter. The hardest part was getting as accurate registration distance as possible. I have no expectations that it will be perfect, but hopefully good enough.

    I ordered my adapter from the site Shapeways. I was just notified this evening that the part made it past their proofing process. They are going ahead with the print.

    M42 threads may be a little more tricky. I have my doubts that 3d printing is good enough to get really accurate machine threads. It may be worth a shot, though. My adapter took a few hours to create and about $30 to get printed and shipped.

    If you want to look into this, I would be happy to share my experience. Also, if mine works, there will be some pictures taken with the Ambi Silette lenses on an E-M10 here in a couple weeks.
    • Like Like x 1
  8. tkbslc

    tkbslc Mu-43 Hall of Famer

    Since respect for mount distance is irrelevant at this point, just buy an fd adapter and a m42 adapter and rig them together some way that blocks any light gaps.