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Thread: Testing for light leaks on film holders

  1. #1
    ki6mf's Avatar
    Join Date
    Nov 2007
    Austin, TX

    Testing for light leaks on film holders

    I had some film spilled by light leaking onto the film and the culprit was where the gaffers tape folds against the baffle that holds the dark slide. The leak was in the middle of the baffle and was easy to miss. I opened the baffles of all my film holders looked through the tape towards a table lamp to check if any of my film holders needed the tape replaced! Simple to do and something I never thought to check!
    Wally Brooks

    Everything is Analog!
    Any Fool Can Shoot Digital!
    Any Coward can shoot a zoom! Use primes and get closer.

  2. #2

    Re: Testing for light leaks on film holders

    Great idea, Wally. I just did that with a holder and saw a leak myself. Did you just patch them with a bit of gaffer's tape??

  3. #3
    hacker extraordinaire
    Join Date
    May 2009
    North Carolina

    Re: Testing for light leaks on film holders

    Typically the tape doesn't matter. The film holder is supposed to be light tight even without the tape.
    Science is what we understand well enough to explain to a computer. Art is everything else we do.
    --A=B by Petkovšek et. al.

  4. #4
    lenser's Avatar
    Join Date
    Jul 2007
    Tim from Missouri

    Re: Testing for light leaks on film holders

    Wally, I suggest you revisit the problem. I just looked at several film holders in my kit, both old and new styles and from different makers. All have a thorough light trap barrier across the flap area that would stop any light leaking through the tape. I suspect yours are the same. If the leak is from the flap end in terms of geography, it sounds more like the holder was not seated in the camera properly.

    If it is from the slide end of the holder, it could be the same seating problem or a remote possibility that you are getting light through the slot for the dark slide if it is bright light and in an extremely direct line to the opening (unlikely, but possible). That's one reason I've opted to always turn the back so that the slotted end is away from the sun and to leave the slide barely tucked into the end of the holder to block any possible stray light from that opening.

    Keep in mind also, that a leak due to an improperly seated holder might look like it is coming from the opposite side than the actual source. That's because the frame of the holder would shadow the film area near the leak source, but the rays would reach the far end.

    Good luck.

    Last edited by lenser; 4-Dec-2010 at 19:14.
    "One of the greatest necessities in America is to discover creative solitude." Carl Sandburg

  5. #5
    Cordless Bungee Jumper Sirius Glass's Avatar
    Join Date
    Aug 2010
    Southern California

    Re: Testing for light leaks on film holders

    Cut paper to 4"x5" [5"x4" in the UK] and load into the holder. Take the holder outside and place it in the bright Sun; turn over and repeat.

    Develop the paper one sheet at a time and you will know which holder and which side of the holder has a problem.

    Repeat above with the offenders to see if you have fixed the problem.

    This was is much cheaper and faster than using film.

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  6. #6
    Gary L. Quay's Avatar
    Join Date
    May 2005
    Fairview, OR

    Re: Testing for light leaks on film holders

    Reviving an old thread.

    I need to test all of my film holders, and we do not have an abundance of bright sunlight right now in the Pacific Northwest. I had one holder loaded with paper in the window for about a week, rotating it occasionally so that every side and angle was exposed to the light from the window. I got little blacks marks on the corners, sometimes up to 3/8" along the edge. I have a few questions relating to this?

    1) Would film be more likely to transmit the light farther into the image? 2) Can I use a bright flashlight and shine it directly along all edges and the light trap? I also have 500W equivalent LED bulbs that I use for studio work. 3) Is there any value in putting the holder into a camera, pulling the slide, and shining the flashlight directly through the light trap, and all around the camera back. Could that make a good holder fail the test?

    I just had my camera professionally repaired, and have been assured that there are no light leaks.


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