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Subject: Re: Film camera question



Luis Ortega spake thus:

> I see a lot of developed film and contact sheets at my school and every once
> in a while I see a roll of negatives or a contact sheet that has a thin band
> of lighter tone (darker on the negatives) at the bottom of most negative
> frames, as if all the frames got a little overexposure only along one edge.
> Usually it's the bottom of the negative frame, and the lighter band is soft
> edged and only about1 or 2 mm thick. The surrounding negative is normal and
> doesn't look fogged.
>
> Could this be caused by the shutter curtains slowing down a little at the
> end of the travel distance thus giving that part of the film a tiny bit more
> light?

Probably not, since most focal-plane shutters travel horizontally across
the frame. A few use vertical-travel curtains.

> I can't determine if these defects correspong to the direction of
> travel of the camera's shutter curtain, but if it was caused by an
> inconsistent shutter curtain speed it should show up along the edge where
> the shutter curtain ends at.

Questions: does the dark band on the negatives extend over the frames?
In other words, is it continuous across the strip of film, or is it only
inside the frames? If continuous, it might be a light leak.

If the bottoms of the frames are all evenly darker (on the negatives)
but the darkness is confined to the frames, then it may be a localized
overdevelopment issue, where the very bottom (or top) of the film is
getting more development. (Assuming normal rollfilm tank development.)

More information, please.


--
I hope that in a few years it [Wikipedia] will be so bloated that it
will simply disintegrate, because I can't stand the thought that this
thing might someday actually be used as a serious reference source.
Because in its current form, it's not to be taken seriously at all.

- Horst Prillinger (see
http://homepage.univie.ac.at/horst.prillinger/blog/archives/2004/06/000623.html)

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