Pentax K to Canon EOS mount adaptor?

Discussion in 'Pentax' started by RiceHigh, Jan 25, 2006.

  1. RiceHigh

    RiceHigh Guest

    Is there any such thing on this planet? And, is there any possible
    mechanical conflict(s) when my KAF-mount lenses are mounted on the EOS
    body, with the mount adaptor (if any) used?

    TIA for any help and info!

    Best Regards,
    RiceHigh, Jan 25, 2006
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  2. RiceHigh

    Jerry L Guest

    Why would you want to do this?

    The lens, if mounted on a EOS body, would only work with the camera in
    Manual mode: no metering, no auto-focus, no decent auto-flash

    If you have K-mount lenses, find a body that (i.e., Pentax) will work
    with that type of lens attached.
    = = =
    Jerry L, Jan 25, 2006
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  3. RiceHigh

    Mark Roberts Guest

    There are m42 (screw mount) adapters for EOS bodies, but not K-to-EOS
    due to image-plane-to-lens-flange distance issues.
    This is about the closest I've seen:
    Mark Roberts, Jan 25, 2006
  4. RiceHigh

    Tony Polson Guest

    The reason why you cannot use Pentax K lenses on Canon EOS bodies has
    nothing to do with "image-plane-to-lens-flange distance issues".
    There are no such issues because the image-plane-to-lens-flange
    distance is **identical** for M42 and Pentax K mounts.

    The reason why you cannot use Pentax K lenses on Canon EOS bodies is
    that the aperture stop-down mechanism on the K lens fouls the camera.

    It is perfectly possible to adapt the SMC Pentax M 28mm shift lens to
    an EOS mount, because it has no aperture stop-down mechanism, being a
    pre-set lens.
    Tony Polson, Jan 25, 2006
  5. RiceHigh

    Espen Mills Guest

    This is correct. Also the Pentax 100mm refelctive has no aperture stop-down
    mechanism. I own this lens, and want to use it with my Canon 10D... So the
    question still is: Does anyone know where/how to get a Pentax (K-mount) to
    Canon EOS adapter?
    Espen Mills, Jan 25, 2006
  6. RiceHigh

    Sarah Brown Guest

    All the EOS bodies that I've used (including my current one, the 5D, on
    which I use some old manual focus lenses) will perform metering and
    automatic exposure (in Av mode) without an EF lens being attached.
    Sarah Brown, Jan 25, 2006
  7. RiceHigh

    Tony Polson Guest

    I don't know of any that are manufactured and sold commercially.

    I know of a company in England that specialises in making adapters for
    photo gear. There must be similar companies around the world.
    Tony Polson, Jan 25, 2006
  8. RiceHigh

    Espen Mills Guest

    I live in Norway, I doubt there is a big enough market for that kind of
    things here... Do you have a name or a website-adress for this company in
    the UK?
    Espen Mills, Jan 25, 2006
  9. RiceHigh

    Mark Roberts Guest

    True, but the K-mount won't fit inside the EOS mount so it would require
    an adapter that spaced the K lens farther away from the body thus
    increasing the image-plane-to-lens-flange distance.
    Mark Roberts, Jan 25, 2006
  10. If the lens to film plane distances are the same, you will still have a
    problem, because the adapter is going to require some space, and this will
    make the adapted lens system too far from the film plane, so a corrective
    lens in the adapter will still be required.....
    William Graham, Jan 25, 2006
  11. RiceHigh

    Tony Polson Guest


    I think you are getting confused. The Pentax K bayonet and M42 screw
    mounts share the same lens flange to film plane dimension. That
    dimension is greater than the lens flange to film plane dimension of
    the Canon EF mount, so there is plenty of room for an adapter.

    Tony Polson, Jan 25, 2006
  12. RiceHigh

    Tony Polson Guest

    Wrong again. You snipped out the part of my reply that explained why.
    Tony Polson, Jan 25, 2006
  13. Ah yes.....You are right. I thought you were going from K to M42, and not
    from EF to K or M42.
    William Graham, Jan 25, 2006
  14. RiceHigh

    Tony Polson Guest

    Sure. Here are the details:

    SRB Film Service
    286 Leagrave Road
    LU3 1RB

    Tel: 00 44 (0)1582 572471
    Fax: 00 44 (0)1582 572535
    Tony Polson, Jan 25, 2006
  15. RiceHigh

    RiceHigh Guest

    RiceHigh, Jan 26, 2006
  16. RiceHigh

    Cheesehead Guest

    Cheesehead, Jan 26, 2006
  17. RiceHigh

    Cheesehead Guest

    How shall we refer to such a wonderful advantage?

    "Optical Improvement for your Canon" ?
    : )

    Where's ol' AnnikaXX when we need him? We can now "fix" his cameras.
    (But unfortunately not his photographic skills.)

    Cheesehead, Jan 26, 2006
  18. RiceHigh

    Mark Roberts Guest

    Well I'll be damned - it looks like it can be done:

    Looks like there's enought difference between Image-Plane to Lens-Flange
    Distance between the two mounts for infinity focus to be maintained,
    Image-Plane to Lens-Flange Dist.
    Canon (FD) 42.1mm
    Minolta 43.5mm
    Canon EOS 44.0mm
    Pentax K 45.5mm
    Contax (old) 45.5mm
    Nikon 46.5mm
    Contax N 48.0mm
    Mark Roberts, Jan 26, 2006
  19. RiceHigh

    Cheesehead Guest

    Imagine, a fine EOS 1v with a 31/1.8 Limited.
    but complete uncoupled.
    Seems a waste except perhaps for tripod use.

    Cheesehead, Jan 26, 2006
  20. RiceHigh

    Tony Polson Guest

    Your apology is accepted.
    Tony Polson, Jan 26, 2006
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