Archived posting to the Leica Users Group, 1999/03/09

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Subject: RE: [Leica] Re:m-6 film scratching.
From: COLBYG@ULV.EDU
Date: Tue, 09 Mar 1999 06:12:02 -0800 (PST)

Hi, Jem,

	Thanks for your thoughtful posts. Among them...

> If all the scratches are in the same position, e.g. in the sky, 1/4" from
> the top edge then it makes looking for the problem easier (as it could
> besomething specific in the camera, though unlikely), if they are 'all over
> the place' then it would point more to a dust/grit scenario.

	I haven't studied the test rolls closely enough, but I think the
scratches are "...all over the place..." Some of them, however, are quite long,
which would discount the idea of debris wound into the film coil at the take-up
spool or within the cassette.

> ...the one thing that comes to my un-mechanically trained mind is the
> relationship between the take up spool and the cogs advancing the film, if
> the take up spool doesn't advance the film far enough then it will be
> winding the film too tightly against itself compared to the transport of the
> film by the cogs, maybe this could be a problem?

	Because one of the cameras (the one doing *most* of the scratching) was
so hard to rewind I got the idea that it might be a problem sliding the film
base against the emulsion within the cassette. The idea you mention came to me
last night. The service professional presently examining my cameras told me
that the new equipment comes from the factory often not very well (correctly)
lubricated. 
	What you suggest here occurred to me last night too. The relationship
between the take-up spool and the sprocket drive must be fairly sensitive. If
it's out of whack the film could be wound too tightly or not tightly
enough...on return to the cassette the same thing could happen again, in
reverse, making matters twice as bad.

- -Gary