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Re: [APML] Focus Problem with Pentax 67

>>>>> "Ray" == Ray Butler <ray.butler@nuigalway.ie> writes:

    Ray> I checked out your page and the image excerpts make it much
    Ray> easier to see what went wrong. This looks to me like a
    Ray> misalignment or tilt between the optics and the focal plane. I
    Ray> can't see how film non-flatness (in the conventional sense)
    Ray> could cause such gross problems, in a gradient all over the
    Ray> entire frame, at f5.6.

    [...]

    Ray> If there's nothing inherently misaligned in the lens optics,
    Ray> this would leave one last possibility. Your statement: "I
    Ray> attempted to have the three knurled-screws that held the lens
    Ray> front to do so snugly but without putting any stress on the
    Ray> lens" might be a clue. Attach the 300mm lens to the camera, and
    Ray> the camera to something solid (such as your equatorial
    Ray> mounting), but don't support the front of the lens. Then push
    Ray> and pull the front of the lens and see how much you can flex
    Ray> it. This indicates the "give" in the bayonet mount, which may
    Ray> need to be tightened up.

I may skip straight to here and take this into the shop.  The bayonet
mount has just the tiniest amout of give in it---enough that locking the
lens in feels different from my 35mm lenses....I just took another look.
Even holding the body on the desk and rocking the lens, I can see a
small gap at the bayonet that changes as I apply gentle pressure to the
lens.  There's a repair shop in mid-town Manhattan that's easy for me to
get to at lunch, so I'll probably drop off the camera.

Thanks!

roland
-- 
                       PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD                             RL Enterprises
roland@rlenter.com                            6818 Madeline Court
roland@astrofoto.org                           Brooklyn, NY 11220
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