Light leak problem?

Discussion in 'Rangefinder Forum' started by mcgrattan, May 2, 2006.

  1. mcgrattan

    mcgrattan Member

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    Hi all,

    Recently I bought a Agfa Optima 1535 -- a short base rangefinder from the late 70s. It's a nice camera but I've been getting this odd light leak on every frame.

    There's a horizontal streak or pair of streaks running across the top of each frame, just a few mm down from the frame edge. The odd thing is that the door edges on this camera are quite a bit away from the film path. I just can't see how it'd be the doors leaking light that causes the problem. Also, this camera has a 'light-shield' that covers the film once it's exposed so it looks like the light leak is happening at exposure time or just before.

    Any suggestions? I include one frame to show the problem.
     

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  2. Kino

    Kino Member

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    It could be a light leak from a pinhole in the camera body that is being painted-on as you wind the film to the next frame. Do you see any "blobs" of exposure regularly spaced along the streaks?

    If not, it suggests either a manufacturing defect OR a pinhole in the camera back that is exposed to direct ambient light when you rewind the film (assuming 35mm cartridges) back to the cassette.

    What film are you using? What Gauge? Did you rewind in bright outdoor light? Did you turn the back of the camera up toward the sky as you rewound?

    You could try cutting a strip of photographic paper to fit the film path of your camera (marking what is up, left, right and down on the back of the paper), load that in total darkness, tie a string to the neck strap lugs, put the camera in direct sunlight and give it a gentle spin to rotate it around for a few minutes.

    Back in the darkroom, process the paper as normal and see if you can find a leak.
     
  3. tommy5c

    tommy5c Member

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    It looks like a flare from the light in the top left. do you have more examples of the same.
     
  4. DBP

    DBP Member

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    Are the light seals on the door foam? Have they been replaced?
     
  5. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    Looks to me like a leaky shutter curtain. Is this a vertical travel focal plane shutter? It could be that the shutter is not closing all the way, and allowing a gap to leak along the curtain edge.
     
  6. Changeling1

    Changeling1 Member

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    Of course in your sample frame, the horizontal line is vertical :wink:

    And it does look like like flare is affecting the left top portion of the frame.
     
  7. mcgrattan

    mcgrattan Member

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    The flare is just a deliberate thing in that shot (I was going for flare - it was sunset and I was facing almost directly into the sun) - I should have chosen a better example!

    The light leak is unrelated and is on every frame - including shots exposed indoors away from any potential source of flare. The problem has occured with 2 different films -- it's a 35mm camera -- and the second of those films was rewound and unloaded in subdued indoor light so it's unlikely to be that either.

    The doors of the camera have no foam seals -- the design is such that the edges of the door fit into narrow and deep grooves. Also, the edges of the door are a long way from the edge of the film - if it was a door leak I'd expect a more diffuse trace on the film.

    The leaky shutter curtain suggestion sounds like a good one -- I've been wracking my brains trying to work it out and that makies sense.
     
  8. Kino

    Kino Member

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    Then there should be a start and stop to the streak on each frame; is there?
     
  9. Jim Jones

    Jim Jones Subscriber

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    Examine the surface of the film closely to see if there is a scratch where the print shows a line. If so, a good cleaning might cure the problem. It could also be a rough spot on the film gate or pressure plate.
     
  10. Kino

    Kino Member

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    Ah, yes; pressure fog...
     
  11. John Koehrer

    John Koehrer Subscriber

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    mcgrattan,
    This thing is a rangefinder isn't it?
    Rules out hole in the curtain I guess.

    Is the streak on the top or bottom of the neg? IE:is it in the sky or foreground in horizontal shots?

    Is it on the base or emulsion side?

    If it's a scratch from the transport you will be able to see it by holding the neg at an angle to a desk or reading lamp.

    If no scratches are apparent it's time to look for a light leak,. Does the shutter close completely? Can you shine a light into the camera both from front and rear and see a pinpoint of light through the shutter?

    Do you experience blobs or dots of light if the film is left in one place for a longer period of time?