[Leica] Fogging film during lens changes

[durling at cox.net (Mike Durling)]

My M4 does it by my IIIf doesn't.  I don't think its the curtains, but 
rather the baffling that the light leaks around.  Could be I need new 
curtains, but its done it since I bought it when it was 7 yrs old.

Just try to remember to waste that frame.

Mike D

Robert Lilley wrote:
> I am relatively newbie to the Leica world and I've been going crazy trying
> to figure out what gives with my screw mount Leica stuff.  Various frames 
> on
> a roll would be fogged seemingly at random.  I thought it was my Leica IIIa
> body or the Summicron 50mm as it always seemed to happen around the use of
> that lens.
> 
> I changed Leica bodies to the older Leica II and did a test roll with all 
> my
> Leica lenses and figured it out.  It's not the lenses or the bodies; it's 
> in
> the lens changes.  Apparently Leica shutter curtains are susceptible to
> stray light.  Sure enough, every time I changed lenses the last frame shot
> got another dose of fogging light whilst the next frame shot with the new
> lens was fine.  Of course it always happened around use of the Summicron -
> it wasn't the Summicron, it was the shot just before the change back that
> got fogged.  Called Sherry Krauter, noted Leica repair person and she said,
> "Oh, yea, you didn't know that - happens with all the screw mounts and 
> M's!?
> I said, "Why doesn't this happen with Japanese cameras, etc?" and she
> shrugged (imagined), "That's just the way it is".
> 
> Being a longer time Exakta user I voiced my woe to that group and got the
> following reply:
> 
> "I was using my Version 1 Varex IIa last week for an entire cartridge and I
> used four different lenses. I don't know how many changes it was, but it 
> was
> more than three or four because I was using my 80mm Biometar most of the
> time. It was the "user" lens and I switched to a 35mm and a 100mm and a
> 150mm. The mirror was up all the time when I was changing the lenses, of
> course, and it was extremely bright sunlight, and I had no fogging.  In 
> fact
> I have never had fogging except when there was a sprung back or bad
> weather-stripping on a camera requiring it.  Considering all the
> photojournalists and other professionals who used Leicas switching lenses
> all the time, I can't imagine they put up with this fogging business
> changing lenses. Although that is my conjecture.  But it seems like we 
> would
> have read about it if it was an inescapable fact of cloth focal plane
> shutters without instant return mirrors."
> 
>  
> 
> I have to agree with the above and wonder if this is something that can be
> corrected as both of my Leica bodies are screw mount and pre-war.  Newer
> bullet proof curtains?!   What say you all?  Thanks for your time.   
> 
>  
> 
> Rob
> 
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