Light Leak Problem

Discussion in 'Camera Building, Repairs & Modification' started by jordanstarr, Nov 5, 2013.

  1. jordanstarr

    jordanstarr Member

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    I'm pretty good at problem solving these things and have solved many camera issues and have repaired nearly every camera problem I've had in the last 15 years, but I'm stumped here. I feel like it's one of those "looking for the ketchup in the fridge and can't find it, because it's so infront of you, you overlook it" scenarios. So, here's the facts, followed by some pictures:

    - The camera is a Leica M4-P
    - The leak is consistently in the same spot in about 25% of the photographs, but it varies in intensity. It spreads vertically, up and down, 8mm from the edge of the film.
    - The leak never goes outside the frame. In some instances it would stop right at the edge with no leak.
    - The leak has not pattern between frames. It might hit 3 in a row and then none for 10.
    - It's worst on sunny days.
    - Last week I shot a "sharpness test" roll with the camera on an overcast day. One subject was a brick wall, 10 feet away, the other subject was a landscape. NO light leaks occurred during this test roll.
    - Upon further inspection of the "nature" of when these leaks show up, they happen mostly between shots where a lot of time lapses between them. When I shoot 5 frames quickly, there's never leaks between those shots.
    - The brightness of the leak is nearly the same intensity all the time, just spread over a bit more. I can burn it in for the most part when printing in the darkroom. I've seen light leaks that KILL the image and make it completely white. This one just changes the density slightly.

    So, my logic was to test the curtains for a pinhole (doesn't leak out of the frame, always in the same spot, bright days show the leak while overcast days don't, is more intense between photos where I do more walking, etc.). I couldn't find one with a light in a darkroom.
    Thought it might be the curtain dragging on a burr on the track, but after 523048 rewinds, I couldn't see any drag.
    Thought it might be a screw on the outside of the body (there's 5 of them). One keeps turning and turning that leads into the take-up spool. I thought it might be that, but given that the leak is ALWAYS 8mm from the edge, it doesn't make sense that it's from the body - otherwise as the film layers increase in the take-up spool, this measurement would change.
    It also cannot be on the camera body on other spots or else it would leak onto the edge of the film.

    So, I'm at a loss. Is it possible that there's extra wear in the curtain that I can't see with my human eye, but over time it while the shutter is chocked (and waiting for the next shot), it's slowly leaking?

    At a loss. Any help would be great. Thanks in advance.
     

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  2. KennyMark

    KennyMark Member

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    Jordan,
    As the leak is only ever within the frame, never between frames, and never above or below, I believe it is reasonable to rule out light penetrating the back, sides, top, or bottom of the body. You could test for leaks from the front by covering the body in a changing bag and making two exposures. First by protruding the lens from the bag and exposing the lens to bright light for several minutes after cocking the shutter and before releasing the shutter while the camera is completely inside the changing bag. Advance the shutter. Secondly by releasing the shutter with the camera inside the bag and then before advancing the film/cocking the shutter, protrude the lens from the bag again and pointing the lens at the bright light again for several minutes.
    This test will tell you if the leak is from the front, and if it is, which curtain is the problem.
     
  3. Born2Late

    Born2Late Subscriber

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    I just had the same problem and suspected a leak at the hinge. I sent a scan to Jon Goodman (makes great seal kits) and he agreed. That is where I would check. I guess you could double check by putting some black tape over the hinge to see if it eliminates the problem.
     
  4. jordanstarr

    jordanstarr Member

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    Kenny,

    Thanks for the advice. I think it's also reasonable to rule out body, top, etc. and focus on the curtains based on that and the consistent location. But the fact that I can't see it is troubling. Even if this test proves that it's coming from the curtains, I guess my question is WHERE on the curtain. I suppose I can get the film and just line it up to the leak with the proper upside-down orientation and smother it in fabric paint or something like that in that area. But I already have one curtain with some patching on it and I worry about patching it up too much. Maybe I should just get over that fear. The worst thing that can happen is that I'll need to replace the curtains anyway.
     
  5. jordanstarr

    jordanstarr Member

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    Born2Late....is your camera a Leica M4-P? This one is and it has no seal kit/foam because the whole thing is designed to interlock to keep light out. The only way it can get it is a bent hinge, metal, etc. on the body from a drop or similar, which this has not had.
     
  6. vysk

    vysk Member

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    If you suspect the curtains, just blast light into the film chamber, without exposing the film and develop the film. You can wind on the film by putting a lens cap on the body, and fire the shutter.

    Do it with the shutter tensioned, and the shutter not tensioned.

    If there is a leak due to the shutter curtain being not light tight, you'll locate it quickly.
     
  7. vysk

    vysk Member

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    Oh, any chance that the edge of the M4-Pdoor flap is leaking light? How about taping it up and see if you don't get a leak?
    The door flap edges are also a set distance from the frame edge.
     
  8. KennyMark

    KennyMark Member

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    Vysk,
    Given the unconventional nature of the M4-P's film path and back, if there is any light leaking from the rear, it would by necessity also be exposing portions of the film outside of the frame.
    My money is on the first curtain having an alignment issue. If Jordan is like most photographers, or if he uses a winder, the film spends more time behind the first curtain than the second. Just a hunch.
     
  9. jochen

    jochen Member

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    Hello,
    I had a similar light leak with my M 2. I sent it to the Leica Customer service together with sample negatives. They charged me a lot of money, allegedly had exchanged the 2 curtains, but the leak was still there. Then I examined the edges of the curtains under a stereomicroscope and discovered a very tiny textile fibre particle between the curtain edges exactly where the leak was. I think the light spot came during transport and cocking of the shutter. I removed it carefully with a pair of tweezers and the problem was solved.
     
  10. jordanstarr

    jordanstarr Member

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    Jochen...thanks for sharing your experience. With some careful troubleshooting, I hope to avoid spending a lot of money.

    Kenny...Thanks again for chiming in. I'll to a test tonight as you suggested and see what's going on. I have a friend who owns a tailor/sewing shop across the street and I'll see if I can score some fabric paint.
     
  11. jordanstarr

    jordanstarr Member

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    ...so I just did the light shining in the curtain test and it turned out negative. I put it up to a lightbulb for about 30 seconds each time. I'll do another test with more time because what I'm noticing is that the shots that it shows up on are times when I was carrying around my camera for about 15 minutes in between photos. If this turns out negative, I'm going to just shoot with my camera in a black bag. haha.
     
  12. shutterfinger

    shutterfinger Subscriber

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    To see the light leak you have you will have to have the camera and yourself in total darkness and the light source outside the total darkness as the leak you have will be a very dim yellow on the order of looking at a candle flame through a #10 welders glass from 10 feet.