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Thread: Suspected light leak with my 11x14

  1. #1

    Suspected light leak with my 11x14

    Last weekend, I made some negatives with my Wisner 11x14 camera, a system which I'm just starting to get into. Two of the negatives were very badly overexposed, and one was so bulletproof that I'd say it was totally exposed. Coincidentally, these two were made with a new Nikkor 450/9 I've gotten, but I think that fact is a red herring. The margins of the negatives show halation where the rails of the film holder were, so I know this is something that happened with the film in the film holder. (I use S&S holders for 11x14.)

    After much head scratching, I remembered another common fact about these two exposures. For one, I had to wait out some wind, and for the other, I had to wait out rapidly changing light. In both cases, I had the holder in the camera with the darkslide pulled for a long time, on the order of 15-30 minutes. My suspicion, therefore, was that there is a very small light leak either in the light trap of the holder or in the camera back that is insignificant when the exposure is made immediately, but is large enough to matter over the course of 15-30 minutes.

    I scratched my head a bit more, and it seems unlikely that both light traps in the same holder would leak light in this way, and additionally, I would think that if the leak were there, that the exposure would be more gradated, with the top of the film being more dramatically overexposed than the bottom. (It wasn't.) I also discount the prospect of a somehow faulty bellows for this same reason. That leaves me with the camera back.

    Given that the only thing keeping the light out of a Wisner with S&S holder inserted is a couple pieces of wood coming together, it seems plausible that this may be the culprit, and I suppose I could make things a little better by doing the old trick of draping the darkcloth over the back of the camera after pulling the darkslide. Do any of the geniuses out there have any comments to offer on my analysis?

  2. #2

    Join Date
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    Suspected light leak with my 11x14

    Sidney: In general, it is best to pull the darkslide (slowly so as not to attract dust) just before you take the picture. I would be uncomfortable with any camera leaving the dark slide out for half an hour. In theory you could do that but it is taking an unnecessary risk. That being said, if the negative is uniformly bulletproof and opaque except for the edges in the slots, I would first explore some other mechanical error like cocking the shutter when open, or pulling the slide before you close the shutter, etc. (I sincerely do not mean those as insulting, and all of us occasionally make such mistakes.) If you really want to know if this is a light leak, set up your camera in the darkroom with the same film holder in it, darkslide pulled, same lens on it, shutter closed, and put a bright flashlight in the camera. After your eyes have adjusted to the dark, turn the camera around on the tripod head and look for light leaks from all angles. Even very small leaks can be found this way. I find it particularly effective to do this with one of those little battery powered survival strobes, which can be leaned against the film holder inside the camera to focus the light there, or moved to the fron to test for leaks there. The on-off nature of the light draws your attention to even the smallest leaks. If you aren't finding a light leak in this manner, then some other explanation is probably it. Good luck.

  3. #3
    MIke Sherck's Avatar
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    Suspected light leak with my 11x14

    Hi, Sid! Glad to hear that you're using the beast. We still expect to see you backpacking it this summer.

    While echoing the previous poster's comments about looking for light leaks, I'm curious about what you mean when you say that two exposures were very badly overexposed. The Nikon is a modern lens with good contrast; if it's an overexposure problem the negative should still exhibit relatively normal local contrast but if non-image forming light has fogged them they should be of very low contrast. Perhaps you can use that to help determine the problem.

    Finally, I always hang my focusing cloth over the back of the camera when a film holder is in. Trying to remove one more variable from the process.

    Mike S.
    Politically, aerodynamically, and fashionably incorrect.

  4. #4

    Suspected light leak with my 11x14

    I had a friend that had the same problem. He started putting his focusing cloth over the camera when he had to leave the film in the camera for long awaited photos. He was also having problems with the bellows coming undone from the camera. Finely after having to do a photo section over twice and costing him a lot of money. He put a new bellows on the camera made by a different bellow company. Hasn't had a problem since. Still puts the dark cloth over the back of the camera not much can be done in that area of the camera. Check the depth of the lock groove that the film holder sits in, his was not the proper depth and that was also giving him problems.

  5. #5

    Suspected light leak with my 11x14

    I really don't think this was a problem of pulling the darkslide with the shutter open or anything like that. I make those mistakes occasionally, but I always immediately know that I've made them, and it's too farfetched to think I would have done that twice and not noticed either time.

    I did test the front of the camera for light leaks, as I suspected improper lens mounting might be at fault (I saw no leak), but I did not check the back. I intend to test the back and the film holder's light trap, and I will make a negative with all of the same equipment, but without the half hour delay between pulling the darkslide and making the exposure.

    I guess on a windy day like that, I should probably come to my senses and instead get out a small format camera like a 4x5.

  6. #6

    Suspected light leak with my 11x14

    Get in touch with Sandy King. I had the same problem with my 11x14 Wisner / S&S holders and he now paints the inside of the wooden flap and has a better design for the light baffle (black cloth) . I sent him my holders and he got me fixed up. Now all of the new holders have these features incorporated into them. It is always a good idea to drape a cloth over your camera and keep your holders away from any unnecessary light to the degree possible. I have Strebor septums for each of my S&S holders in 11x14 and 12x20.

    All is not lost Sidney.........

    Cheers!

  7. #7

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    Suspected light leak with my 11x14

    Always treat the ULF like it is ultra light sensitive and you will have better luck. Your dark cloth is your best friend in this regard to counteract the light where it can get in. Be especially careful when moving the darkslide in and out. Perhaps grip the back tightly to make sure it doesnt move when you do this.Never leave the darkslide out a second more than the required amount for the process of removal, exposure, and reentry.

  8. #8

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    Suspected light leak with my 11x14

    Sidney,

    There are a lot of things that can cause light leaks in ULF besides the normal things we think of.

    Try taking the filmback off the camera with a holder inserted in the camera. Check to see if the film holder sits perfectly flat in the spring back. There is always a chance that something is in the way and not allowing the holder to sit flat in the spring back.

    Also the lock bar on the holder might not be sitting in groove on the springback allowing the holder to raise up from the back. I have also found that some holder (and spring backs) stick and don't put the full pressure on the holder.
    _______________________
    George Losse
    www.georgelosse.com

  9. #9

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    Suspected light leak with my 11x14

    This perhaps isn't the cause of your problem but regardless of that I think that pulling the dark slide and leaving the holder uncovered in the camera for fifteen minutes or longer isn't a good practice. After getting a lot of light leaks when I first started using large format cameras I now make it a practice to toss the dark cloth over the back of the camera to cover the open end of the film holder, no matter what the lighting conditions are or how long the exposure is. I make plenty of mistakes, I don't hold myself out as a paragon of large format perfection, but I haven't had a light leak that I can recall since starting this practice 8 years ago.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  10. #10

    Suspected light leak with my 11x14

    Thanks for the suggestions. I made a test negative tonight being more careful with how long the darkslide was withdrawn, and after development, the negative looked fine, so that's an easy fix.

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