[Leica] Interesting technical problem--your thoughts?

[amr3 at uwm.edu (Alan Magayne-Roshak)]

On Tue, 11 Mar 2014  Jim Shulman <jshulman at judgecrater.com> wrote:
Subject: [Leica] Interesting technical problem--your thoughts? 

>After processing, I noticed that several of the frames seemed 
>to have a strange fogging, almost like a crescent dagger from the bottom of 
>the frame (bottom, as in what was in the bottom of the camera) about every 
>so often, maybe five frames total out of 40. 

>http://gallery.leica-users.org/v/focusit/filca+fog.jpg.html 

>One suggestion I've received is that there's a tiny light leak near the 
>take-up spool, based on the sharp definition of the leak pattern.  If 
>that's the case, though, why not on both FILCA and non-FILCA loads?  After 
all, the take up spool has nothing to do with the type of film cartridge. 

>Thanks, 

>Jim Shulman 

>Wynnewood, PA
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I think regular cassettes (with the felt light traps) hold the film under a 
little tension, whereas the metal cassettes with an opening slit can allow 
the film to have some slack which might let any leak to get to the emulsion. 
 The tension in the FILCA might be different at various times, thus making 
the fogging random.

That's my speculation.

I had a different fogging problem with my IIIc in the 70's.  I used to get a 
few frames on each roll with a thin fog stripe from top to bottom of the 
frame, but on the end of the frame toward the take up spool.  I finally 
figured out that light was hitting the film as it bent around the sprocket 
gears.  I think the pressure plate was not tight, so that light would bounce 
off the shiny emulsion and fog the previous frame where it was slack.  The 
film was not tight in the film channel.  To solve the problem, I used a 
paper clip taped between the film aperture and the sprocket shaft (behind 
the film) to push the film forward onto the gears.  I never had the fogging 
again (and never got any scratching from the fix).


Alan

Alan Magayne-Roshak, Senior Photographer
University of Wisconsin-Milwaukee Photo Services
(Retired)
UPAA POY 1978
amr3 at uwm.edu
http://gallery.leica-users.org/v/Alan+Magayne-Roshak/

"All the technique in the world doesn't compensate
 for an inability to notice. " - Elliott Erwitt