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Thread: Light leak - please help diagnose

  1. #1

    Light leak - please help diagnose

    Folks,

    Thanks for the very helpful information in my previous thread. I scanned a sample showing the light leak I described and was wondering if you could help me diagnose it. I did get a couple of good exposures from the same lens, which leads me to believe it may be a sporadic problem with the shutter not closing all the way. I tested the lens on 2 lensboards and it sits flush and light-tight so I'm pretty sure the leak is not between the lens and board or between the board and camera. The previous owner told me the lens was sitting idle for over 2 years so it's possible a CLA is in order.

    Here's what it looks like:



    Thanks!
    Guy

  2. #2

    Join Date
    Dec 1999
    Location
    Forest Grove, Ore.
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    3,696

    Light leak - please help diagnose

    What camera are you using? What was the approximate aperture for this photo? Are you using some sort of lens shade? What kind of shutter are you using?

    There's a large volume of light reflecting off the sand. Do you experience the same problem in less contrasty circumstances?

  3. #3

    Light leak - please help diagnose

    Camera: Wista VX (used with other lenses on the same trip with no problem)
    Aperture: f/32, I believe
    No lens shade, but the same leak appeared in other scenes with no direct light
    Lens: Nikkor M 300/9
    Shutter: Original Copal 1

    Thanks!
    Guy

  4. #4

    Join Date
    Mar 1999
    Posts
    769

    Light leak - please help diagnose

    Check the bellows for pinholes by taking the camera into a dark room, inserting a film holder in the back and inserting a flashlight through the front standard - any pinhole should be quite obvious. Remember to try extensive movements - some pinholes are often hidden by folds in the bellows and only reveal themselve when flexed. I've found preserving your dark vision makes it easier to spot the pinholes, so try to avoid shining the flashlight into your eye. Check the seating of the film holder in the back. You can also check the lensboard while you are at it by removing the film holder, placing lens on the front panel and shining the flashlight on it from the outside and looking through the back. But I doubt it is going to be there - pinholes near the lens area tend to form double images. If you look at the sample picture you have posted, the left hand and top sides look relatively free from flare. The flare light seems to start in the top left region towards the middle and sprays across the film area towards the bottom right. The flare seems highest in the top left region and seems lower as you move away from that region. This suggests that the flare light was close to the top left corner, hence the higher intensity of flare there and lower intensity a greater distance from it. If you can figure out the orientation of the film in the back (which you can from the notches), I would think that you are going to find the leak near the top left corner of the picture area close to the back standard. I'm assuming that this is not an issue of the film holder not sitting properly in the back through operator error. Cheers, DJ

  5. #5

    Light leak - please help diagnose

    Thanks DJ! I just tried the light in the bellows thing and there are no visible leaks anywhere on the bellows.
    Guy

  6. #6

    Join Date
    Mar 2002
    Location
    the Netherlands
    Posts
    116

    Light leak - please help diagnose

    I have had a light leak in my camera some years ago that produced a similar result. In my case it was a light leak between the bellows material and the metal frame that attaches the bellows to the rear standard. It took me quite some time to figure out that one of the screws in the bellows frame was broken and hence the cloth was no longer attached leak proof to the frame. The screw had of course not fallen out so it was not apparent at first sight... I suppose a leak between bellows frame and rear standard would also produce an effect like this.

    I just compared your scan to one of the transparancies I saved and they look very much alike (the leak, not the scenery). I have no experience with the Wista camera, so I can't really tell if this could be what's causing your problem, but I think it's an idea to check your bellows and bellows attachment to the camera for a leak. Succes, Jan

  7. #7
    Tracy Storer's Avatar
    Join Date
    Nov 2001
    Location
    Oakland CA
    Posts
    907

    Light leak - please help diagnose

    Guy, DJ has the right idea....we also need to remember this is your 300mm, and Wistas with a not overly long bellows. When you checked the bellows, was it racked out to around 12"? I would further guess it IS a bellows leak, near the back of the bellows, on the lower right. (users right, looking at the back of the camera) Also check that the bellows isn't separating from the back when you rack out. Good luck, let us know,
    Tracy Storer
    Mammoth Camera Company tm
    www.mammothcamera.com

  8. #8

    Light leak - please help diagnose

    I'm a bit confused. Are we worried about the light, center part of the image, thinking it's a leak, or are we concerned with the darker, underexposed area toward the outer edges of the frame? To me, the outside looks like the bellows are interfering by sagging or something. At least the snow looks dark...the trees look a bit light on the inside, tho. And at 300mm it's easy to imagine. Guy, does that look like it could be the problem?

  9. #9

    Light leak - please help diagnose

    Gary - that's an interesting point I haven't thought of, but I think the lighter part in the center is the problem since you can see some ghosting there and it's not evenly exposed (the upper right corner is brighter than the rest). The bellows was certainly not sagging. As someone mentioned, the Wista has a fairly short bellows and it was stretched out to capacity with the 300mm.
    OK, I removed the bellows and found some separation between the leather and plastic frame holding it in one corner. I super-glued it and am about to venture out for a couple of test shots. I do hope that turns out to be the problem!
    I'll report back when I pick up my film at the lab tomorrow.

    Guy

  10. #10

    Light leak - please help diagnose

    Guy,

    As the flare shows a straight border, it looks like a shadow from the wood frame in contact with film-holder. Probably, if you insert it on place you may find a leak at bottom on the right side. Good luck!

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