[Leica] Viso III release adjustment

["Simon Pulman-Jones" <spulmanjones@lbs.ac.uk>]

This one is of rather minority interest, I think. I have just had a rather
odd experience with my Viso III. I have used it without problems on an M2
for a few years now - until recently, when I found that some pictures that I
had taken on a recent holiday appeared oddly un-exposed, with only a thin
exposed portion along the bottom of the frame. The LUG was spared my
puzzling about how on earth this could have come about on a horizontal focal
plane rangefinder camera when I realised that these were pictures that I had
taken with the 200 Telyt on the Viso. Obviously the shutter release arm was
out of adjustment. But when I checked it I found that however I adjusted the
screw on the arm the Viso mirror would not lift before the shutter when set
to the yellow-dot instant-up position. The same was the case when I tried
the Viso on my M5 with the M5 arm fitted.

Completely baffled, and foreseeing a trip to the repairer, I recklessly took
the plunge and took the jeweller's screwdrivers to the Viso. After a few
nervous moments as the release mechanism came free, and several springs
jumped loose, during which I was overcome with a sinking feeling of regret,
I began to be able to un-fathom the mechanism. It turns out that there is a
small eccentric cam which controls the point at which the mirror-lift is
triggered, and which was at the position resulting in latest possible
release. I turned it to the position giving earliest triggering of the
mirror-lift, and now find that the shutter-arm can be properly adjusted to
work on both the M2 and the M5 - though the margin on the M5 is rather
small.

I find it hard to imagine how this small cam could have changed its
position. When I turned it to re-adjust it, it was quite stiff. It appears
to have happened when the Viso was in a camera case in the hold of the plane
we took on holiday, but I find it hard to imagine even the wildest baggage
handlers being able to have that effect on the Viso - none of the other gear
in the case showed any signs of distress.

Has anybody else has this experience of the Viso release mechanism going out
of adjustment?