Help figuring out light leak

[tonyluong]

I apologize for the amateur thread but I am having a hard time diagnosing a sheet of film I just got back. I was out this weekend for a short few minutes wanting to make some type of photograph after being rained/snowed in. I exposed 3 other sheets and there were no issues like this, the lab I used was a local one I don't really go to all too often since it has had a reputation of messing up film (water spots, streaks, etc) but it was the closest and I just wanted to test out the new 150mm I got.

Could someone tell me if this is a light leak or if it is a problem that occurred during developing?

Thanks all,
Tony

http://i54.photobucket.com/albums/g104/toldey/light_leak.jpg

[Gem Singer]

The picture seems to be an enlarged image of a small section of the original.

Difficult to tell for certain, but it doesn't appear to be a light leak.

Could it be lens flare??

Need to see the entire image, including the outer edges, not cropped or magnified in order to make an accurate diagnosis.

[tonyluong]

Unfortunately, I can't get a full scan at the moment. I usually rent out an imacon for a few hours when I have more than 3 sheets to scan. To me, it seems like something happened during developing?

[Jim Michael]

If the leak occurred during the processing (or other film handling) stage then I would expect the black edge to be fogged. If the leak occurred while the film was in the holder I would expect no or less fogging on the edge.

[al olson]

I notice, Tony, that you have exposure along the edges of the rebate. The stronger exposure at the top near the notches becomes weaker as it crosses the rebate, but then seems to emerge again into the image. The exposure on the bottom rebate is also brightest at the edge.

It would appear that a beam of light struck the top edge and then "light-piped" its path down through the base, exiting out the bottom edge but exposing some of the emulsion on the way.

Since the notch end of the film is usually inserted so that it is at the flap end of the holder, this might imply that there is a hole in the tape holding the bottom flap. Most flaps, however, also have baffles that mate with baffles on the holder to prevent light leaks. But this would be one place to check.

If it is evident that there is no light leak on the flap end of the holder, then the fact that there is exposure on the rebate would indicate that it did not happen while the edges were masked inside the holder. This suggests a handling issue. The question then would be: why is it so localized?

I am stretching for ideas here, but something had to flash the edge. I have never tested for exposure to the luminous dial of my watch because I put it into my pocket before I start loading. But it could happen that the dial of your watch was up against the edge at some point.

Another possibility could be that the film was placed near a luminous strip in the darkroom. I work with luminous strips placed at strategic locations and I have never had a problem, but I don't put film or paper right next to them.

Beyond that, I can't think of anything else in the darkroom that would be such a narrow light source on an open sheet of film.

This is my two bits ... about what it's worth.

[tonyluong]

al olson - I appreciate your input! Perhaps I will try to check the holder. My other sheets that were from the test came out perfectly fine so somewhere along the process of the holder to developing, the problem arose. Interesting though, I have never had any problem since I last used the holder until I wanted to test the new camera.

[Gem Singer]

Test the new camera?

Pinhole in the bellows?