Archived posting to the Leica Users Group, 2005/09/27

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Subject: [Leica] Foto with my IIIf and Voigtlander 35mm
From: jblack at ambio.net (John Black)
Date: Tue Sep 27 12:07:32 2005
References: <3ee867269fbf5740278a4b99eaed93b1@mac.com> <4339906E.9030706@summaventures.com>


> >
> > The film is showing streaks on bright areas, although they are
> > intermitent. My guess is that it is the curtain..I don't know. After all
> > I will have to send the camera for check-up.
> >
> > Here it is....
> >
> > http://www.photo.net/photodb/photo?photo_id=3760181
> >
> >

I think I know exactly what that is...  Had the problem with LTM cameras
myself.  I'll bet the shutter speed was high, perhaps 1/500 or 1/1000.  If
you will notice, the fabric of the curtains is wrapped around the end of the
blind edges and sewn, unlike M camera blind edges which have metal "lips".
When set to very high speeds, the shutter merely creates a very narrow
"slit" between the first and second curtain that travels across the film
plane.  When shutters get old and need readjustment, the slit is too small
and the texture of the fabric creates "bumps" in the slit that double or
halve the effective speed by narrowing the gap.  Normally this is not a
problem as the slit is wide enough that the fabric texture only accounts for
maybe 10-20% variation, not 50%.  The M shutter corrected this by providing
a sharp, smooth metal edge for the traveling slit.

Get a good CLA and it will go away.

JB




Replies: Reply from firkin at ncable.net.au (Alastair Firkin) ([Leica] Foto with my IIIf and Voigtlander 35mm)
Reply from cochranpr at mac.com (David Cochran) ([Leica] Foto with my IIIf and Voigtlander 35mm)
In reply to: Message from cochranpr at mac.com (David Cochran) ([Leica] Foto with my IIIf and Voigtlander 35mm)
Message from pdzwig at summaventures.com (Peter Dzwig) ([Leica] Foto with my IIIf and Voigtlander 35mm)