Yashicha Mat - flare? reflection? light leak?

Discussion in 'Medium Format Cameras and Accessories' started by Marcin P, Jul 2, 2012.

  1. Marcin P

    Marcin P Member

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    Hi there,

    I'm experiencing some annoying problem with my Yashica Mat. At random, strange light streaks appear on my negatives. It's always at the same position and the same shape, only intensity varies from non to really heavy. It happens in all lighting conditions and directions of light. Also it's always within a frame and never on the borders.

    What I have tried so far:

    - I am using an original lens hood.
    - I have flocked the entire interior of the film chamber with black matte material.
    - I have checked the lens and there is no trace of fungus or dirt.

    img733.jpg
    img746.jpg
    img747.jpg
    img748.jpg



    Can it be a light leak if it doesn't appear on the borders? Please help!

    Many thanks,
    Marcin
     
  2. DWThomas

    DWThomas Subscriber

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    The radiating pattern suggests to me it might be the shutter not closing fully or a pinhole sort of leak -- but that's pretty speculative on my part.
     
  3. Ian Grant

    Ian Grant Subscriber

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    I agree with Dave it looks like the shutter blades aren't shutting fully.

    Ian
     
    Last edited by a moderator: Jul 2, 2012
  4. Dan Daniel

    Dan Daniel Subscriber

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    The shutter leaves hanging up is a possibility. Another might be a leak at the felt trap that surround the barrel you see at the back of the lens. There is a felt ring at the opening of the body to the film chamber. I had a terrible time tracking down a leak in a Rolleiflex that involved light coming through the focusing screen, going around the viewing lens (no light trap at that opening), then finding its way through the automat mechanism onto a silver roller in the film source chamber.... whew, what a tricky mess. Anyway, the focus hood IS a source of light that can get behind the lens panel. But it then needs a leak into the film chamber to do what you have.

    You might try the old bellows check thing- in a dark room, put a flashlight inside the film chamber and check for light coming out. Maybe fire the shutter and see if you catch the blades lagging just a bit? Put the light in the focus hood and see if it finds it way into the film chamber?

    Good luck- light leaks can be a real bear to track down. But oyturs looks very specific and repeatable, which is actually a good thing for diagnosing.
     
  5. Marcin P

    Marcin P Member

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    Much appreciated guys!

    Indeed there seem to be a trace of some kind of black dirt, oil perhaps on the the edges of the blades. I have called a guy who is fixing analogue cameras and I will have it serviced next week. I should have done that long time ago, but the problem wasn't so frequent.

    I don't think it's a light leak but I will do the test Daniel suggested. I hope this can be fixed as I really like this camera.
     
  6. T-grain

    T-grain Member

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    Marcin,
    as already told, it is probably the shutter blades. May I just add, from my personal experience: keep an eye on film flatness-I had a major problem with it-the images weren't sharp because the film was out of focal plane. It were the springs of the film pressure plate being too weak.
    just my 2 cents
     
  7. johara

    johara Member

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    One other possibility to consider: If you "kink" (sharply bend) the film when loading it onto the reel for development, that can cause streaks as well. That's not too hard to do considering how thin 120 film is. I've done it myself from time to time.
     
  8. wharris

    wharris Member

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    reminds me of those photos you see with "ghosts" in them lol.. i happen to like them =)
     
  9. Marcin P

    Marcin P Member

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    Hi guys,

    As advised by a camera repair guy in my city I did some testing (he thinks it's a light leak), holding the camera in the sun with lens covered and uncovered, but not taking any shots. It turned out the pattern is visible throughout the entire film so it's definitely a light leak and not a shutter problem. The fact that it's only within a frame suggests that it happens in the film chamber. I did some testing in the dark room with a flashlight and suprisingly I there are no leaks from the front or sides to the chamber.

    The only possibility I can think of is that the light is coming from the back and somehow is reflected to the film plane in the chamber. Any idea how can I trace this down?
     
  10. jochen

    jochen Member

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    Hello,
    put a little electric bulb or LED with thin wires into the camera, close the back in total darkness, accomodate your eyes to the darkness, put on the bulb and look. Perhaps you can locate the leak. Or you can put a stripe of black electric tape on the slit between camera body and back, than you expose the camera loaded with cheap film to the sun. Stepwise you can put the stripe on other places.
     
  11. Dan Daniel

    Dan Daniel Subscriber

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    I'll mention the felt light seal around the back of the lens barrel again. Here's a photo of the area- the lower opening in the silver plate is where the felt trap is-

    5791034378_ce121d8b05.jpg

    If you open the back and move the lens to close focus, the rear barrel will move forward and you might be able to just see the felt.

    A problem I had with a Rolleiflex 2.8C was solved with an added light trap around the viewing lens. Best as I could ever figure, the light was coming through the focus screen. This could be a source for your light?

    http://www.rangefinderforum.com/forums/showthread.php?t=106282&highlight=leak

    Another flashlight test with a light in the focus hood and the back open? Or a test roll with the hood left closed for a period/group of shots (remember, a leak like this isn't just when the shutter is fired). Also, the flash sync lever slot is open to the top of the shutter/light trap area, another possible source. Tape this over?
     
  12. rolleiman

    rolleiman Member

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    Did it happen with just the one roll of film?..If so, then another possibility is the film not being sealed tightly enough prior to development.
     
  13. Marcin P

    Marcin P Member

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    Thanks for all the advices. No, it happened with many rolls, always the same pattern and the same placement, like it's beeing reflected off something. I will try again with the back slit taped with black tape.
     
  14. snederhiser

    snederhiser Member

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    Hello Marcin;
    Your shutter needs to be serviced. The blades of the shutter should be clean and no oil present. A good service is cheaper than wasting film, Steven.
     
  15. Dan Daniel

    Dan Daniel Subscriber

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    The OP says that he tripped the shutter with a lens cap on and still got the leak pattern. How could a lagging shutter blade cause that?
     
  16. Marcin P

    Marcin P Member

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    Hi Guys,

    I did another flash light test in the darkroom and spotted a leak coming from the focus screen (Dan you were right). I added some sealing around the viewing lens and the problem seems solved - I've just developed a roll and despite sunny conditions no white streak is present.
    Thanks a million everybody!

    Best regards,
    Marcin
     
  17. Dan Daniel

    Dan Daniel Subscriber

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    Hope it stays clear of fog!

    Some day you should replace the felt seal. If it is leaking, light will some day find another path to the leak, and it will be a shot you will always regret losing if my luck holds true for you! Like the M/X sync lever slot? A little tab of electrical tape as a safety?

    You might send Mark Hama an email and ask if he has seen your leak before. Tell him what you have done, see what he says?