Nikon F2 Help

Hello everyone,

A friend recently got me a Nikon F2 that was very cheap. I have been able to confirm that the camera seems to work fine, with the exception of the slower speeds which doesn't surprise me. Anyway, I have put two rolls through it, one color 400 ISO one and one long expired roll of Tri-X 400. They take fine pictures other than a few frames show a strange artifact. I was wondering if this could be because of failing light seals? I have uploaded a couple of photos from the Tri-X roll in the hope that someone will know. These artifacts appear exactly the same on the color film, except that they are a whiteish blue color.
Thanks

If the light seals are starting to fail replace them. If sunlight is hitting the viewfinder eyepeice then light entering through the viewfinder can fog film.

I definitely wouldn't define the images you posted as "fine pictures", the actual picture is barely visible in the second frame, while the first frame is just a grey rectangle showing the artifact you describe. Were all other frames indeed "fine pictures" with good contrast, image definition etc.? It is impossible to guess anything by pictures as poor as those you posted, they show so many issues all together that the cause may be literally whatever, or a mix of whatever with whatever else, from lens to shutter to the camera body to the film itself to development and so on.

"other than a few frames" there were fine pictures". You can check the seals with anything
that fits the grooves they're in. If the foam doesn't compress and expand as you press it, it's shot.

The photos appear to be extremely underexposed - I assume the corresponding negatives are equally thin in density. The intermittent / interrupted rectangles of light don't appear to be flare or something a light leak would produce, though I suppose it's possible. Even if it is a light leak, I'm baffled why it would appear identical in such a precise form or structure across several frames and rolls of film.