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Thread: long exposure light leak?

  1. #21

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    Re: long exposure light leak?

    and how did the light test go?



    .

  2. #22

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    Re: long exposure light leak?

    Quote Originally Posted by Paul Ron View Post
    and how did the light test go?



    .
    Took the camera into a darkened room, removed the front lens panel and pointed a bright LED torch directly underneath the Graflok (where it joins to the rear standard). Pitch-black, couldn't see any light leaking through...

    TBH I cant see how any light could get through, the Graflok and standard are chunky pieces of metal, could they wear/bend/warp?

  3. #23

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    Re: long exposure light leak?

    the leak doesnt have to be that large. it only has to pass a joining surface and can be as small as a pin prick. it takes very careful inspection of every meeting surface and dont forget to test the bellows.

    it doesnt have to be warpage or deformaties. it may be a weak spring or mismatched joint due to dirt or even a lose screw. worn seals, depending on your camera, are always suspect. is this a wood camera?

    did you also try the light from the rear to see if the lensboard is leaking?

    if the problem happens with other film holders, the leak is from the camera.

    just be patient n do the test again looking closely at everything, not just point the light at a single component. if you can, use a regular house led bulb, a small focused beam is too directional.

    btw,... the light source goes inside the camera.

  4. #24
    loujon
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    Re: long exposure light leak?

    Go in darkroom take lens board off PUT FLASH LIGHT INSIDE the CAMERA put lens board back on. sit 10-20 minutes to let eyes fully adjust to darkness. FLASH LIGHT GOES INSIDE OPENED/set up camera with a holder in spring back & pull slide out of holder for good measure. Now study camera from all angles and see if any pin holes of light can be detected.

  5. #25

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    Re: long exposure light leak?

    Louis makes a good point: be sure to check for leaks with a filmholder in the camera. Check at all orientations of the back too.

    Doremus

  6. #26
    Tracy Storer's Avatar
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    Re: long exposure light leak?

    is it possible there is something shiny INSIDE the camera ? I have seen this more than once where there's a problem surface, and it'll show only with the back oriented one way.

    You could tell us what kind of camera it is, how old, etc.
    Tracy Storer
    Mammoth Camera Company tm
    www.mammothcamera.com

  7. #27

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    Re: long exposure light leak?

    Quote Originally Posted by Tracy Storer View Post
    is it possible there is something shiny INSIDE the camera ? I have seen this more than once where there's a problem surface, and it'll show only with the back oriented one way.

    You could tell us what kind of camera it is, how old, etc.
    Hi Tracy,

    Its a Sinar F1 with wide-angle bag-bellows. The bag-bellows are in good condition, hardly used. However the rear standard looks pretty old.

    Here is another shot with a different lens (Schneider 150mm) and lens-board. The contrast is cranked up to better show the leak.

    Click image for larger version. 

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    The rear standard has a soft gasket inside the groove where the graflok sits (along the bottom edge). This picture seems to point to that gasket (it does look worn and squashed). When the graflok is in landscape orientation that bottom edge is covered by a ridge in the graflok. Only two sides have that ridge. In portrait orientation there is no ridge to block the leak coming from the bottom edge.

    Click image for larger version. 

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    Is it possible to scrape out that gasket and replace with a DIY one?

  8. #28
    Vaughn's Avatar
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    Re: long exposure light leak?

    The rear standard has a soft gasket inside the groove where the graflok sits (along the bottom edge). This picture seems to point to that gasket (it does look worn and squashed). When the graflok is in landscape orientation that bottom edge is covered by a ridge in the graflok. Only two sides have that ridge. In portrait orientation there is no ridge to block the leak coming from the bottom edge.
    That is something the flashlight test would easily show if done as suggested by Louis.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  9. #29

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    Re: long exposure light leak?

    Quote Originally Posted by Louis Pacilla View Post
    Go in darkroom take lens board off PUT FLASH LIGHT INSIDE the CAMERA put lens board back on. sit 10-20 minutes to let eyes fully adjust to darkness. FLASH LIGHT GOES INSIDE OPENED/set up camera with a holder in spring back & pull slide out of holder for good measure. Now study camera from all angles and see if any pin holes of light can be detected.
    Hi Louis,

    Finally got around to trying this again after the Christmas holidays.

    There are tiny leaks in both bottom corners of the rear standard, where the Graflok attaches to the back of the rear-standard, and where bellows attaches to the front of the rear-standard

    Looking at the light-pattern of the leak I bet there are other leaks along the bottom edge that I cant detect.

    I have some sticky felt gasket I can try cutting to size and putting in the corners...

  10. #30
    loujon
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    Re: long exposure light leak?

    Quote Originally Posted by MattKHardy View Post
    Hi Louis,

    Finally got around to trying this again after the Christmas holidays.

    There are tiny leaks in both bottom corners of the rear standard, where the Graflok attaches to the back of the rear-standard, and where bellows attaches to the front of the rear-standard

    Looking at the light-pattern of the leak I bet there are other leaks along the bottom edge that I cant detect.

    I have some sticky felt gasket I can try cutting to size and putting in the corners...
    Great! Once you've located the leak/leaks the next step (your doing) patch the leaks do another light leak test to make sure you've corrected the leak. Now try the camera out in field and see if the leak is gone.

    Your on the road to a success!

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