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?
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