I am having a strange light leak problem that has me stumped. It happens with my 8x10" Ansco/Agfa camera which was completely rebuilt before I bought it not long ago. The bellows are brand new and light- proof. There is no consistent pattern to the fogging. Approximately 1/2 of the sheets that I shoot are badly fogged. The other half are perfect. The camera is totally light proof which I have tested repeatedly by removing the lens board and looking into the camera while under a sealed dark cloth with inserted holders in both vertical and horizontal position and with the slides in and out and by checking from the back with back removed and operating the shutter. The fogging is different on each sheet which provides a clue but I have not been able to figure out what is causing the problem. Sometimes the entire sheet is fogged so badly that you cannot see the exposed image. Sometimes the fogging comes from one corner and fans out across part of the sheet and sometimes it comes from another corner. Sometimes the edges are clear and sometimes they are fogged. Sometimes part of the edges are clear while it is fogged in other areas. I even had one sheet that was fogged all over with the exception of a small relatively unfogged area several inches long and a couple inches wide near the middle of the sheet! The fact that sometimes the film is fogged on the edges would indicate that something is happening when the film is not loaded but, as I said, sometimes the edges are free of fog. I have been shooting large format for over 30 years and my loading and processing methods have never changed and I have never had a problem like this. Consistency is my watchword. The film is loaded and unloaded at the same time and under the same conditions. In the field, I use a changing bag and, when on the road, I sometimes load and unload film in a hotel bathroom with not only all lights off in the bathroom, but with the hotel room dark and at night so there is no possibility of leaks around the door. Besides, I have had this problem when the film was loaded in my normal changing bag which I also use to change all my 4x5" film which has never been fogged. I load both 4x5" and 8x10" film in the same sessions and under the same conditions. After first experiencing this problem, and after checking the camera carefully for light leaks, I suspected that the film holders may have not been seated totally. I found that it is possible for them to be seated incorrectly with this camera if care was not exercised but it is easy to see if they are inserted correctly once you are aware of this. In fact, I was confident that this was the problem. So the next time out, I very carefully and consciously checked to make sure they were seated properly. I thought for sure that the problem was solved and was very surprised to see fogging again. Just out of curiosity, I checked the camera with the lensboard removed and a holder inserted improperly but there were still no light leaks unless it was the holder was grossly unseated. My processing is the same as it has always been too although I recently switched from tray to line-tank processing for sheet film when processing large amounts of film. However, before I switched, I had the same erratic fogging with 8x10 processed in trays while all 4x5" film was fine. In addition, about half the 8x10" sheets that I load and process together (in the same batch) are fogged while the other half is fine. For example, last week I processed 51 sheets of 4x5" film that all came out fine as usual and then, in the same session, I processed 4 8x10 sheets in the same tanks with the same chemistry (replenished between batches). The four sheets were processed side-by-side in holders which where in a rack for lowering into the chemistry. Two sheets were perfect and two sheets were badly fogged. By badly, I mean that one was so bad that you could not see the image at all except for a small area in the middle of the film and the other was fogged so that you could only see the image on about 1/2 of the film. The fogging gradually faded as it neared the center of the film leaving about 1/3 of the sheet fog free. But, perhaps not coincidentally, the two good sheets were TMax100 and the two fogged sheets were TRI-X. Unfortunately, I can't remember if it was only TRI-X that came out bad in previous runs so it is possible, of course, that I simply have a bad batch of TRI-X but it would seem to me that the sheets would have fairly uniform fogging if that were the case and it wouldn't explain why sometimes the edges of the film are fogged and other times it's clear. Last time out, as an extra precaution, I left the camera covered with my very large dark cloth right up to the lens and removed and replaced the slides with the cloth covering the camera. There was no change. Half the film was still fogged. I always minimize the time that the dark slide is removed. It is the very last thing that I do before releasing the shutter with the exception of instances where I am waiting for a lull in a breeze to still moving grasses or plants in the foreground but that was not the case with the two bad sheets this time. The subject was static without changing light levels so the slides were only out long enough to make the exposure. I remove slides completely. One last thing. I have a variety of new and older (but sound) film holders but the film that fogged this time was in a brand new (never used once) Fidelity Elite holder. Both sheets were of the same subject, shot one after the other. What I know is: 1) All my film, both 4x5" and 8x10" is loaded and processed under the same conditions and at the same time. 2) I have never had light leaks of any kind ever in 4x5". 3) I got fogging with a brand new holder. 4) Testing from the back and front of the camera shows no light leaks at all. The fogging has occurred both before and after my lens received a CLA and total checkup from Grimes. Unfortunately, I only have one lens for 8x10" (14" Kodak Commercial Ektar). 5) It is possible that I have only had this problem with TRI-X but, unfortunately, I can't remember if any TMax100 fogged previously. When this started happening, I thought it was an equipment problem (light leak) and just never thought about that (like a dummy). I have always prided myself in being able to logically analyze and diagnose technical problems of all kinds but this one really has me stumped. It's erratic. I would appreciate any ideas you can share. I apologize for the long post but I reviewed other threads on this topic and I wanted to answer questions that would be asked if I didn't go into detail.