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  1. #11
    erikg's Avatar
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    This is pretty common, I've seen it before. These are internal reflections of a sort, as ic-racer said, and light piping through the film base. You notice it most in the areas with heavy exposure. Light can travel sideways through the film base, AH dyes or no, if the exposure is heavy enough. I wouldn't worry about it.

  2. #12

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    You are not using 220 film with the camera on the 120 setting by any chance? The 120 setting assumes film plus backing for the pressure plate position.

    The borders showing the effect are adjacent to the film rails. The length of the effect matches the length of the frame, has a sharp boundary. I do not see any signs of a double image. If the film had moved due to the back not being fully latched (you have to press both corners of the back on a C330 to ensure full and even latching) it would have to be during exposure. And that should cause a double image.

    Low level light leak seems to be a possibility. That would imply the long edges of the back, or possibly the internal lens change baffle if the lens was removed. The shape of the fogged area suggests a uniform effect. But since the effect does not involve the edge of the film, it is unlikely to have originated anywhere except the film gate.

    If it is camera body fogging you should be able to replicate it by doing everything you would do normally, but expose the frame with a lens cap on.

    The pictures here show the film gate for a C330, which may help discussion.
    http://grahampatterson.home.comcast....c330/c330.html
    I feel, therefore I photograph.

  3. #13
    PeterB's Avatar
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    Attached drawing shows how artefact 1 is created outside the film frame

    Thanks Gerald, if the lens board was loose the artefact #1 on each side would be diffuse, in fact they are very sharp and well defined. It is possible a light leak is contributing to artefact #2.
    erikg, I tend to agree with your analysis about the piping with intense light. That could explain artefact #2.
    Graham, no I'm using 120 film. Interestingly the pressure plate doesn't actually press tightly on the film edges, it presses on two parallel rails either side and slightly higher than the film rails - see the diagram below I drew.

    I'm now pretty convinced in the explanation(for artefact #1) offered by ic-racer whereby the light reflects off the film surface at the edges and bounces off a recess back onto the film outside the frame area - the picture shows it better.

    Click image for larger version. 

Name:	IMAG0403_cross section of Mamiya C330.jpg 
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  4. #14
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    Quote Originally Posted by PeterB View Post
    Thanks Mark. I'm unsure what to test for if the lens is faulty.
    The 150SF is a soft focus lens, in perfect order, the aberrations are designed in.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  5. #15
    michaelbsc's Avatar
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    You might try some flocking material. If there is a place you can actually put it, that is.
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

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