"Luis Ortega" wrote

something that is happening only inside the negative frame itself.

If this is 35mm, something everyone seems to be assuming,
I'll toss my hat in with the sticky-vertical-shutter crowd.
Vertical shutters were used on Exa's and Exakta 500s -- if there is
one of these hanging around I'd bet money it's the one with the problem.

A light leak is the usual culprit but 35mm cameras as a rule don't
leak light into the mirror box. Is the film fogged or overexposed?

You should only see this in contact sheets from one camera and
one photographer unless the class shares common camera(s).

Probably a good idea to report the problem to the camera owner/
class instructor. The problem will only get worse with time and
the shutter may stop completely in cold weather.


--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics, Photonics, Informatics.
Remove blanks to reply: n o lindan at ix . netcom . com
f-Stop enlarging timers: http://www.nolindan.com/da/fstop/