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Thread: Pre-exposure dust on film

  1. #1

    Pre-exposure dust on film

    I am new to LF and have found this forum to be a great help. With tips from prev ious posts, I have had good results so far (especially the "slosher" for film de veloping--what a great device!).

    My problem: processed film has had spots that are completely clear as if there w as dust on the film before exposure. I have been diligent about cleaning film ho lders when loading. I have been shooting in very cold conditions. Could static b e the culprit and can it be lessened/prevented? Any tips to prevent this problem ?

    If this is a problem that can't be avoided, any tips on retouching B&W film?

    Thanks in advance. Those of you with experience are a great resource for us newb ies.

    Greg

  2. #2

    Pre-exposure dust on film

    Greg, I too suffer from this from time to time despite being meticulous in the c leaning of the DD slides before loading. I think some of the dust settles on the film when you remove the dark slide prior to making the exposure. Either from s urface dust on the slide itself or from within the camera. Things have improved somewhat since I've started useing an air blower on the slide before I remove i t. I will be most interested what others have to say on the matter.

    Good luck,

  3. #3

    Pre-exposure dust on film

    Static can be a real problem, especially in cold and dry conditions. My negatives sometimes give off a real light show in the darkroom when I remove them from the plastic protectors for printing. The static is a real dust magnet!!!

    When exposing the film, I think it's important to remove the darkslide slowly to avoid creating static inside the camera. -Dave

  4. #4

    Pre-exposure dust on film

    You have touched on one of the more difficult things to deal with in large format photography. It has been discussed a number of times on this forum in previous posts. Check them out. Here is my two cents worth. I live in very damp Western Washington. Dust on negatives is not much of a problem here, but I do travel to dry climates a lot where it is a problem.

    I usually clean my holders with some antistatic spray periodically (the stuff used for computers). I also vacum them out before I load film each time (again a little computer vacum), hit them with the air gun and brush with antistatic brush. I turn on the hot water in my darkroom sink to increase the humidity in the darkroom and load the film. The loaded holders go into a plastic bag. They go into a different plastic bag after exposure. I also dust my holders off with an antistatic brush before putting them into the camera back. Finally I remove the darkslide slowly. All of this helps, but when in the desert I shoot readyloads to avoid the whole issue. I do this begrudgingly because I prefer Tri-x, but this is another issue.

    I have found no easy way to fix the dust spots after you get them. I have played with various methods of retouching the negative with little luck. When it happens I either crop the negative if possible, through it away or if the spot is small enough I etch the print very carefully. I use a high magnification head set to do etching and spotting. It is pretty amazing how these spots always seem to find their way to the sky where everyone can see them.

    Good Luck

  5. #5

    Pre-exposure dust on film

    Most people forget that the largest repository of dust in their holders is the light trap. This has to be cleaned periodically to keep the dust from collecting along the felt and being dragged into the film space with reinsertion of the darkslide. A good strong blast of air will dislodge most of this dust. Since I have been doing this, 99% of my dust problems has gone away even when I am out in the desert southwest. James

  6. #6

    Join Date
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    Pre-exposure dust on film

    If you're shooting 4x5, the Schneider Hi End Back system reportedly includes a mechanism that sweeps away dust when you pull the slide to expose. I haven't seen it myself, but others say they've not had dust problems when using this system.

  7. #7

    Pre-exposure dust on film

    Greg: One of the contributors to dust on the film, especially in dry cold weather, is the camera itself. The dust can be knocked loose when setting up or transporting the camera and static electricity sucks it onto the neg. I would suggest a good cleaning of the inside of the camera. Extend the bellows as far as possible, remove the lens board and back, and get out the vaccuum cleaner. Put the hose of the vaccuum cleaner in the front, turn it on, and tap the bellows all over to loosen any stuck particles. You might even cut the handle off a small paint brush and use the brush to loosen dust inside the bellows. If your camera back does not remove, put a spacer under the spring back to hold it open so air can circulate. Also give the rear of the lensboard and camera back a good vaccuuming. I would also give the holders a thorough vaccuming. While you have the vaccuum running, go over the area where you load film. Just walking in the darkroom stirs up a lot of dust. Even with these safeguards, you will still find occasional dust spots on the neg. The safest way to retouch the negs with dust spots is to work on the back side of the negative. Put the neg on a light box or whatever and gently scratch the BACK of the neg over the spot (NOT THE EMULSION SIDE). The scratch will scatter the light, making the area white. You can also try a soft very sharp pencil on the area. You can then spot the print. The rule of thumb is that the more white clouds and sky in the photograph, the more dust spots you have. Hope this helps.

    Regards,

  8. #8
    Robert A. Zeichner's Avatar
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    Pre-exposure dust on film

    I have just one more suggestion to add to the list of good ones posted so far. A technique that has worked very well for me is to place the stack of fresh film base up. I have for some time suspected that dust settles on the film before it ever gets loaded in the holder. If the emulsion is down, the time that it is exposed to the room atmosphere is reduced significantly. The mere action of moving your hands, the holder, etc. has to stir up the air and unless you are loading your holders on a laminar flow bench in a laboratory, there has got to be dust and other particulates floating around. Like I said, this has worked very well for me and I find myself having to do less and less retouching of the negatives as a result.

  9. #9

    Pre-exposure dust on film

    Dust! Dust drives me crazy. All that work to clean your gear to avoid it, but some how it always seems to leave its mark on your film. Here is what I have done to get rid of it. When ever possible I use Kodak Readyloads which are made of paper. I have never had any dust spots when I use the Readyloads. Unfortunately they are only available for 4x5s, restricted to specifc types of film, and cost lots more. However, the price is cheap compared to the cost of waste do to dust spots. When I head for the mountains fo a month with food, film, and llamas, waste is a much bigger issue.

    When I am forced to use traditional film holders, I have taken the liberity to make some modifications. First, I replaced the plastic dark slides with metal. I could never understand why they use plastic for a slide. I have also screwed a snap on button to the handle end of the slide. I then snap on a conductive cord that looks like a long shoelace to the snap on the slide. The cord is long enough to touch the ground. Before I retract the slide I step on the cord to make sure it is well grounded.

    By using a metal slide that I ground, I can draw off any charges that may build up. When I do this, dust only shows itself on occations.

  10. #10

    Pre-exposure dust on film

    A minor addition to the numerous excellent ideas: Wear a cap, a hat, anything that keeps your head from dropping particles. It is not only hair that falls onto the food that requires that chefs and even cooks at fast food outlets wear them. It is the dusty stuff that makes your film as unpalatable as your food.

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