on 5/26/02 9:26 PM, Scott Gomez at scott@xxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
> Thanks for the off-list picture, Moose!
>
> I agree with you regarding the mechanical linkage and that there's no way it
> should fire the shutter... however, further investigation with the Winder
> disconnected and the camera in various positions shows I can fairly reliably
> trip the shutter regardless of position. All I have to do is cycle the DOF
> preview button fairly rapidly a few times (number of times varies, according
> to no pattern I can discern). I'll try it again with a different lens, also.
>
> I did note the 85/2 is a bit sluggish in the aperture blades, too. *sigh*
>
> ---
> Scott Gomez
>
> -----Original Message-----
> From: dreammoose [mailto:dreammoose@xxxxxxxxx]
> Subject: Re: [OM] OM-4T Anomaly
>
> Since there is no mechanical connection that could cause the shutter to
> fire and the OM-4 is an electronic camera, I suspect something is
> shorting out. I doubt it has anything to do with the DOF button in
> particular, but just pressing on the lens at that place and angle angle
> and perhaps with holding the camera a particular way while doing so. The
> first thing I would try is taking off the winder, since it can fire the
> shutter and uses electrical connections to the camera that can be
> intermittant if very slightly damp/dirty/corroded when wiggled by hands
> flexing around the front and bottom of the camera. Winder connections
> being randomly connected and disconnected with varying resistance could
> easily confuse the circuit. Second, I would suspect that there was an
> intermittant contact or short in the camera that was being flexed by
> pushing on the lens in the mount.
>
> <snip>
>
> Moose
There are some mechanical connections inside the camera between the aperture
mechanism and the shutter mechanism, there are 'interlocks' or levers that
move out of the way to release one after the other. If by wiggling the DOF
mechanism a few times you are jarring the mechanism and inadvertently
signaling 'all clear to fire the shutter' then that could cause the shutter
to trip without the button getting pressed.
As I play around with various old cameras (trying to learn to repair them,
but mostly disassemblying and getting 'bag-o-cameras') I discover that the
interactions between these little levers and pins and springs can be very
subtle, it doesn't take much to release the chain, and often you can start
it in the middle of the mechanism if you push on a particular lever or such.
I suspect Clinton or John H. can tell you if this is a probable cause. In
normal use it is probably unlikely, but the camera could be OK and still
have it happen if something inside there was right at the edge of being out
of line enough to really matter...
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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