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Thread: Light leak - driving me mad for weeks

  1. #1

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    Light leak - driving me mad for weeks

    So my first post here, and sorry it's a problem.

    Here is a 4x5 negative (FP4+) and I keep getting these light leaks, they are never the same, but always at the top (trap end of the holder).

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    The leaks can be full width of the neg and as you can see it looks like its getting fogged before or after being in the film holder. I thought I had tracked it down to possibly getting light in my Calumet Film Changing Room/tent. So I did two things, loaded the holders/tank in a Paterson film changing bag (Great no fogging) then added an extra elasticated strap to the arms of the Calumet tent so each arm hole now has two restrictions instead of just one. And for bolt and braces also covered the tent in black cloth. I always do this is a room with no lights on with curtains closed, not dark, but no strong light. For a few sessions ( 6 or so negatives) no fogging , then I got this one. The other neg on side b of the same holder was loaded up and put in the tank at the same time and that was fine.

    I can't track it down to any film holder, I have 6 and it can happen to any. The tank is the Stearman Press SP-445, and I have 2 of these, again no correlation with which tank used.

    Is it possible to get fogging like this from faulty film holders, I can't see it, as I said I have 6 of them and are all new Toyo holders. The camera is a Cambo Legend, used indoors. Tried different bellows, checked for leaks etc.

    Can anyone help ?

    Thank you,

    Mike

  2. #2
    Corran's Avatar
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    Re: Light leak - driving me mad for weeks

    I think you can rule out film holders because your top rebate wouldn't be fogged like that if it was your holders. But, you could do some systematic testing to check. Perhaps buy some cheap x-ray film to use instead of "real" film.

    I don't use tents or the Stearman tank so I'll let others comment on that.

    BTW nice gears, crop the top off and you've got a good photo still .
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  3. #3
    C. D. Keth's Avatar
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    Re: Light leak - driving me mad for weeks

    When you load your tank, do you load so that the notched end of the film is up in the tank?


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  4. #4
    Vaughn's Avatar
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    Re: Light leak - driving me mad for weeks

    You can see the 'shadow' of the notches of one piece of film cast onto the negative you showed us (upper right side). One neg was laying cross-wise on the other when the light snuck in. While loading or unloading the holders, probably...or while getting ready to develop.

    But it should not be a 'shadow' -- but a clue nevertheless!

    Sorry...having too much fun...back to the two negs laying on top of each other: the light gets 'piped' in between the two sheets of film from the edge -- but does not get piped in where the notch is because there is no film there...thus no exposure where the notch is. Note that the upper right corner of the film is not exposed -- measuring the distance, this corner is right where the second big notch of the top piece of film would be -- and no piping of the light.

    And from the looks -- more than two sheets of film involved.

    So your holders and camera are good to go. Look elsewhere for the leak.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  5. #5

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    Re: Light leak - driving me mad for weeks

    "Trap end"? You mean the top where the dark slide inserts? Or the bottom(as the film holder inserts in the back) where the flap is for loading the film?
    "My forumla for successful printing remains ordinary chemicals, an ordinary enlarger, music, a bottle of scotch - and stubbornness." W. Eugene Smith

  6. #6
    Peter
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    Re: Light leak - driving me mad for weeks

    I wonder whether you have a reflection inside the bellows striking your film as you're making the exposure. I inverted your negative image to view it as a positive, then put a curve adjustment on the light leak to increase the contrast enough to find the hotspot. The light leak doesn't seem to be as bright at the edges, as expected, but seems to be in the center of the light leak. If it were brighter at the edges you could assume the light was coming in from outside the film holder and dissipating as it spread across the film. Here it seems to dissipate outward in all directions from an area in a bit from the edge.

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  7. #7

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    Re: Light leak - driving me mad for weeks

    process a sheet straight from the box, which may or may not be the problem. is it bagged or double boxed ?
    notch codes ? I only use one film...

  8. #8
    Gary Beasley's Avatar
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    Re: Light leak - driving me mad for weeks

    Looks like a pinhole in whatever the film was in, the box it came still in good shape?

  9. #9

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    Re: Light leak - driving me mad for weeks

    Wow! thank you all very much, lots of pointers there for me to look at. Rather than post lots of separate replies I will do a single recap one here...

    [Corran]
    >I think you can rule out film holders...

    Yes that is the conclusion I thought as well.

    [Chris]
    >When you load your tank, do you load so that the notched end of the film is up in the tank?

    Yes I do.
    Also the fact that two negs developed together in the same tank should rule out the tank, plus as I said I have used 2 tanks.


    [Vaughn]
    >...back to the two negs laying on top of each other...

    Never at any time were two negs on top of each other, I take one out of the box at a time, the rest never leaving the folded card that covers the film sheets.

    [Willie]
    >"Trap end"? You mean the top where the dark slide inserts? Or the bottom (as the film holder inserts in the back) where the flap is for loading the film?

    Sorry wrong terminology, I mean the flap end where the film is loaded.

    [Peter]
    >I wonder whether you have a reflection inside the bellows striking your film as you're making the exposure

    I did have that effect early on, took me a while to realise what was happening, no it's not that, I now check for brighter areas outside the image area and either use a lens hood, and or I mask off those areas with flags, black cloth etc actually around the subject I am shooting.
    Your other point:

    >The light leak doesn't seem to be as bright at the edges, as expected
    I think this is just the effect of the image area receiving the image photons plus the light leakso that exposes the film more in those areas.

    [Fred]
    >process a sheet straight from the box, which may or may not be the problem. is it bagged or double boxed ?

    I tried that early on and it was ok, film is bagged and boxed, the example above is double boxed.

    [Gary]
    >Looks like a pinhole in whatever the film was in, the box it came still in good shape?

    No this is happening from 3 different boxes & two different film typs (FP4+ and Foma 100)


    Recap: So it looks like I can rule out a camera or film holder problem, and it looks like 'operator error' in someway, when I am either loading the film holders, or taking film out of the holders and straight into the developing tank. I have not been storing exposed negs in a box.

    Just to add more info in case it helps, all the exposures are quite long, in the order of 30 sec to 5 mins as they are taken indoors, low light levels and small apertures.

    From the pattern on the right hand edge, I thinking along the line of I may be pausing slightly with the film almost in the holder because there is a repeat shadow whch I have marked on one of the negs below.

    I also add a few more negs to show the variation. If this is happening while loading/unloading the film holder, I am very surprised that this can happen when I have gone to extra lengths to make the changing tent more light tight.

    Thanks again for your observations.

    Mike
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  10. #10

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    Re: Light leak - driving me mad for weeks

    How well do the film holders fit in the back of the camera? It appears you may be getting light leaks at the bottom. Causes could be poor fit, you not having the holder in fully or not tight at the bottom. Maybe not enough spring pressure at the bottom and somehow you are pulling and inserting the darkslide and causing the bottom to move. Pushing into the back when removing and replacing the dark slide might help here.

    How well does the back fit on the camera? Check that for any leaks. Since they are all coming from the same end it is a process of elimination.

    For now, when you put the holder in the camera do the "Morley Baer wrap" around it with the dark cloth and make sure you have the bottom area covered well.
    "My forumla for successful printing remains ordinary chemicals, an ordinary enlarger, music, a bottle of scotch - and stubbornness." W. Eugene Smith

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