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Thread: Light Leak or Pilot Error

  1. #1

    Light Leak or Pilot Error

    Your indulgence for a moment, please.

    I believe what I have encountered is my rank incompetance yet again rearing it's ugly head, and yet I worry that perhaps it may be something more problematic.

    I shoot 8 X 10 almost exclusively. My holders, all used, are mostly wooden and of post-war vintage, but in excellent condition. I have used them for at least t wo years now, with no complaints, until...

    I have two negatives, exposed within days of each other, with the same camera, b ut in different locations, with different lenses and different holders. Both a re horizontal exposures. One was made in bright sunlight, late afternoon, the o ther indoors in subdued, shadowy lighting. They are both fogged in almost exact ly, if not exactly the same way, on the same portion of the negative. Other neg atives, loaded from the same box, on or about the same time have so far prooven unfogged.

    The fog is about 1 - 1.5 inches in from the corner diagonally opposed to the not ch code, on the long side. So, standing at the camera back, looking forward, th is would be on the upper right long edge of the negative, as the exposure was ma de. The fog extends down, or into the picture area, thinning out and becoming l ess dense the further away from the film edge it gets. The fogging on the negat ive exposed indoors is less severe than the negative exposed outdoors. In both cases, the fog starts beyond the normal unexposed area of the film, where the ho lder would block the light from striking it, creating the usual black border.

    I always load horizontals into the camera from the right as you stand behind it. Occassionally I will load by taking the back off the camera, inserting the hol der, and then replacing the back. This is easier to do than just sliding the ho lder in, without disturbing the cameras position, as I am rather short and the b ack has fairly strong springs.

    I suspect that what has occured is that in replacing the back I did not exercise adequate caution in ensuring that the dark cloth did not get caught between the camera and the back when it was replaced, forcing a slight gap between the two, which fogged the film when the slide was pulled.

    However, the fact that the fog is in the same exact position and extends beyond the border has me concerned that either I have a wierd and very consistent probl em in my darkroom, or that I have somehow managed to ruin two (and maybe more?) holders in exactly the same way.

    Waddaya Think? Have I correctly self-diagnosed, or am I totally wacked out and wasting your time? Or both? Sorry for being so verbose with what may be an obv ious problem. Thanks and enjoy your Memorial Day Holiday

  2. #2

    Join Date
    Sep 1998
    Oregon now (formerly Austria)

    Light Leak or Pilot Error

    Sean, Here are a couple of questions and a couple of ideas that may help you identify your problem. First, is the film fogged out to the edge, i.e., is the border whi ch is normally blocked by the film holder fogged? If so, I doubt the fogging is happening in-camera. If not, your suggestion sounds good. However, you should gi ve the camera a thourough inspection as you should your film holders. Another po ssible source, and something which I have done a time or two (or more!): When yo u insert the dark slide after making the exposure, make extra sure you are inser ting it into the film holder slot and not between the film holder and camera bac k. This, of course, levers the back open and can cause light leaks and seems som etimes as if the darkslide simply got crossed and stuck requiring you to pull it and try again. Take a couple of loaded film holders and try out your possible " mistakes". If you end up with the same fogging then you've found your culprit. H ope this helps Regards, ;^D>

  3. #3

    Light Leak or Pilot Error

    Is there crud stuck in the light trap channel? Or did you somehow get the holder in slightly crooked?

  4. #4

    Light Leak or Pilot Error

    sean you say the fog is in the same place but not exactly the same intensity? Have you checked your bellows? I can't imagine you fogging the same place with your holders/removing replacing thing but around the bellows or where the lens is attached to the board or where the board attaches to the camera. All can swell and shrink and leak light. As I reread your post when you say diagonally opposed?? How do you attach your lens to the camera? Is there a diagonal there? good luck.

  5. #5

    Light Leak or Pilot Error

    Sean, A simple yet effective way of checking for light leaks:

    In a very dark room, place a flashlight (turned on, of course) inside the view c amera's body/bellows, with a lens attached (shutter closed), and a film holder i n place (with the dark slide inserted and/or removed).

    Let your eyes adjust to the dark room and after a bit you'll clearly see any lig ht leaks in the bellows body, bellows, back and lens attachment points, etc. If the light can get out, it can surely get in.

    Fixing the light leaks, assuming you have any, is another matter. Good luck, S ergio.

  6. #6

    Join Date
    Mar 1999

    Light Leak or Pilot Error

    hi sounds like an almost similar problem i had. the fogging would not be to the edges of the film (therefore, not fogged in the darkroom or due to exposing the whole film). it would begin a little way into the image area (so, i would have a small bit to the edge which was well exposed and high contrast) and the fog would begin here and reduce contrast over the rest of the image area. kept notes, could not trace it to a particular holder.

    i can think of two reasons. one, a bright light source out of the angle of view (i.e., the film does not see it) but within the angle of coverage (i.e., but the lens does) which gets bounced off the bellows and deposited as a flare across the film. from your description, this sounds unlikely (given one of your shots was in subdued, indoor lighting). The second (which, as it turned out, was my problem) is a leak close to the film plane. if it is not in the holder seating etc, it has to be in the bellows. the bellows comes under the greatest stress close to the standards and often develops holes at the corners here. now, if you pull the dark slide, there is light leaking in from these holes and spraying across the film. since the leak is so close to the film plane, light enters at quite a steep angle.. so the region close to the edge doesn't get fogged but the rest of the area does. have tried a diagram below to explain this. pinhole | bellows| light | ___________________________________ film { }{ fogged area } i would try loading my holder with some paper. now insert the holder, pull the dark slide (but don't trip the shutter), keep the whole set up in the sun (or even better, shile a bright light all aruond the bellows), reinsert the dark slide (paper is slower than film and you might need to keep it in the sun for a little while). develop the paper and see if it has got fogged. hope this ramble helps. thanks dj

  7. #7

    Light Leak or Pilot Error

    My money is on a pinhole light leak. I had a similar problem recently, and only a high intensity flashlight, and a dark room, revealed the VERY small pinhole in the lens board. Check your camera out as described above. Good luck.

  8. #8

    Light Leak or Pilot Error


    Thanks for the responses thus far. The bellows is only a year old and I should hope that that isn't the trouble, but I shall check.

    Since posting I have developed two negs. exposed the same exact time, date, place, location, etc. etc. etc. (except the holder) as the 2nd, less fogged negative, and they came out fine. I was waiting for the light to move across the subject a bit and see which exposure/composition I liked best later, so except for the passing of time - perhaps 12 minutes all told - whatever was wrong, were it mechanical, except for the holder, would presumably be repeated on all three negs.

    I reloaded both of the suspected holders before processing commenced, so I guess I shall have to wait and see what happens to those negs to rule out the holders entirely.

    I've been using the same camera, holders, bellows, lenses, etc. for a year, perhaps 100 8 X 10 negs altogether, and this is the first occassion I have found (I've been checking older negs) that this has occured. I suppose that's part of the reason for my concern, I thought the kit was intact.

    Any additional suggestions?

  9. #9

    Light Leak or Pilot Error

    Aha! Sort of. Followed Sergio, et. al.'s advice and found a small, barely discenable, and very regular shaped light leak in the bellows. So the glue is drying as we speak.


    I then processed another neg, taken on a different day, got the same fogged streak. One big difference though - this neg is a vertical, all the rest have been horizontal. The fog moved with the neg. In other words, the leak must be in the back! Now I examined this carefully and thoroughly when I got the first fogged neg. I have seated several holders and they all seem just fine, flush with the back/bottom of the back, no discernable gaps between the holder and the face of the back..... What am I overlooking?

  10. #10

    Light Leak or Pilot Error

    Put a holder in the back and take out the lens board. Drape your darkcloth over the front standard, look into the camera, and shine a very bright light onto the back. Move it around so you can see the light leak. You should be able to see it if it's there. Are you still sure it is in the back and not the holder? Let me know. Put a peice of film in the same holder that you got the light streak with. Put a light all around the holder at different angles and then process the film. Is the streak still there? James

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