I would appreciate any advice on the following problem. I Have recently had a problem with a very fine staright line of light density visible along the length of a 35mm film (FP4+ & Delta 100). The The line has not always appeared at the same place in each roll of film in which the problem has occurred. Its trace can be seen between the negs too. The films were processed in a small tank in a quite normal manor. On close inspection of the emulsion the line is clearly not a scratch. I guess it may be friction related but would appreciate any opinions.

thanks

-- Jonathan Cordle (jcordle@paston.co.uk), July 01, 1999

Answers

The only phenomenon that spontaneously comes to mind would be static electricity: When the film is rewound under conditions favouring static electricty (e.g. dry air, certain material combinations), it is possible that an electric discharge occurs between the film and the cartidge. The electric arc caused by this discharge might result in local exposure of the film.

-- Thomas Wollstein (wollstein@compuserve.com), July 02, 1999.

Wouldn't a static discharge result in a dark line?

I wonder if it is a film manufacturing problem. You should certainly examine your camera. Does it also occur in the film leader?

-- Alan Gibson (Alan.Gibson@technologist.com), July 02, 1999.

Because you say that the mark is a fine, straight line, I think it almost has to be from some mechanical cause, like grit in the film path somewhere within the camera, or a nick on the pressure plate: something like that. Static marks show up as "stars" or "lighting bolts" in an irregular pattern, not the straight line you mention. Alan's question about whether it appears in the leader portion of the film is a good one. Another thing that comes to mind is how you are handling and loading the film into the tank. Some tanks come with various gadgets to help get the film seated into the tank grooves. There is a possibility of some kind of sharp edge there too. Possibly chemical contamination, though I dont think that would make as sharp a mark as you describe. Get out your strongest loupe and examine camera and processing equipment as carefully as you can. Use your fingertips to see if you can find any hint of a rough spot anywhere.

Oh, one other thing -- is this mark only one one type of film that you bought at one time, or does it show up on all your films, regardless of type, and when purchased? If only on one type of film, indicates possible manufacturing fault. If on all of them, most likely your equipment. Good Luck

-- Tony Brent (ajbrent@mich.com), July 02, 1999.

I've had these problems with my former Nikon FE too, the lines sometimes turned up and sometimes weren't there, on B&W (developed by myself) and on slide film (which I do not develop myself). I've always attributed this to static electricity provoked by rewinding your film on the cassette too fast. Just rewind it slowly and see if you still get lines. If you do, I wouldn't know.

-- Lot (lotw@wxs.nl), July 03, 1999.

Thanks for the responses to date. I will answer one or two of the questions raised. The films I most noticed the problem in were a roll of Delta 100, where the mark was right through from frame 1 to 36. The other was a roll of FP4 where it started about half way through the roll and was in a more midway position on the roll. The tank I use is a standard Patteson one and I did have a few totally unaffected films in between. The camera in both cases was a Nikon F3. I have thoroughly checked the camera. It was in need of a clean inside but was by no means that bad. There is a very slight rough patch in the camera between the film guides and this would probably have been caused by the film leader during countless rewinds. The emulsion surface shouldn't be in contact with this area and this would not correspond with the position of the line on one of the films anyway as it was too high. I had not considered static. Thanks again.

-- Jonathan Cordle (jcordle@paston.co.uk), July 05, 1999.

go to this url; http://www.dr5.net/faq.html and look about the middle of the page 'problem with some ilford films' this might be an 'ilford' issue. as far as ive seen this type of line ive only seen in pentax cameras. it might be a film type issue

drwood

-- drwood (drwood@drwood.com), July 10, 1999.

Jonathan, sometimes when the film is scratched prior to the processing of it , the scratch will effect the image but not leave any visable traces on the surface. the processing of the film fixes the gouging. if the film has had the emulsion pulled to one side slightly, it will be very fine, and slightly denser. tho this sounds very unlikely becaues you have mentioned nothing of a thinner edge to the line. Just a shot in the dark. Sean

-- Sean (ZBeeblebrox42@yahoo.com), July 12, 1999.