foggy doggy

Discussion in 'B&W: Film, Paper, Chemistry' started by smieglitz, Nov 28, 2012.

  1. smieglitz

    smieglitz Subscriber

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    This fogged film problem has me baffled as to the origin of the fogging source. Notice the V-shaped diagonal lines where the frames were not fogged as heavily. Also, I don't see any pattern of film perforations cross-cutting the fogged areas as would be the case when film gets fogged outside of the cartridge when loading the tank in a loading room. In-camera fogging also does not seem to be the culprit because there is no evidence of fogging paralleling and immediately adjacent to the perforations.

    A student had this happen to one of the rolls she developed in our community college darkroom yesterday. She developed two rolls in a double-reel Paterson System-4 tank and she swears she used the proper tube in the tank. The film looks something like an improper tube had been used because the top is more fogged than the bottom of the frames (and the lower roll had very, very slight fog along the perforations on one edge but the fog on that roll did not extend into any part of the images). Typically, when a tank/tube mismatch is the problem, the film in the centermost spiral is more fogged than the film in the outer spirals. That doesn't seem to be the case here as the worst areas appear in a periodic fashion rather than increasing steadily from the top and center outward.

    I've checked the tank, lids, tubes, darkroom, and interrogated the student as to whether the film might have gone through an X-ray machine at an airport, if anyone could have opened the camera back while it was loaded, (or opened the darkroom door), or if a cell phone or watch lit up in the loading room when she was handling the film, etc. Nothing seems to have been out of the ordinary and I've never seen a pattern of fogging like this particular film exhibits.

    Any ideas on what caused this fogging or what the "V" shape is?

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  2. MattKing

    MattKing Subscriber

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    Based on the frame numbering, I'm assuming that the film came from a factory loaded cassette.

    Is there any chance the student popped the end off of the cassette before turning off the lights?
     
  3. smieglitz

    smieglitz Subscriber

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    I suppose there is a chance, but she insists there was nothing different compared to how the previous rolls were processed. Also, the second roll in the tank was very slightly fogged so it wouldn't be just a single cassette at fault.

    I thought I'd seen every way a film could be ruined many years ago but this is a new one to me. I'm stumped.
     
  4. TheFlyingCamera

    TheFlyingCamera Membership Council

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    There could be some kind of flaw in the lid of the tank that allowed such a strange leak.
     
  5. smieglitz

    smieglitz Subscriber

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    Scott,

    I thoroughly checked the tank and all parts to it. Nothing was cracked or leaking light that I could see. If it was the tank, I suspect the second roll would have been fogged much more than it was given how extreme the fogging was on the other roll. A crack or hole in the tank would need to be fairly large and obvious to get the extent of fog present.

    But, it does seem that the tank and light baffle has to be the culprit. To get that "V" the film would need to have been folded over itself if something fogged it from the outer edge or the light would have to radiate out from the center if the film was wrapped around something. Looking at the pattern, the fogging is worse between the diagonal lines of the V-shape. The angle of the diagonal lines seems fairly consistent so the film was probably being held in some sort of symmetrical orientation when it was lightstruck.

    Maybe the flange was mistakenly placed up in the tank to cause some sort of gap on one side. The "V" might be spokes in the reel blocking fog coming from one edge although I would imagine any lines from that would be curved due to the spiral holding the film. I did ask the student if she had any trouble locking the tank which usually is the case when the flange is upside down. She again said she didn't have a problem.