Re: [Leica] flash contacts

[Stanley E Yoder <syoder+@andrew.cmu.edu>]

    If memory serves, this was hashed through here a couple of months
ago. I reported that the same artifact [flash fires when shutter release
depressed with UNcocked shutter] happens with my IIIf LTM.
    I thought we determined that the circuit has two contacts in series,
i.e., both must be closed to complete. One contact is closed when (and
while) the release is depressed. The second is closed when the leading
curtain completes its travel (but before the trailing curtain begins to
close the aperture - this is presuming X-synch).
    Before the shutter is wound for the next exposure, the leading
curtain is still at the end of its travel and the contact is closed.
Depressing the release will close its contact and the circuit is again
completed.
    The purpose of the release contact is to break the circuit at all
times OTHER THAN when the exposure is made, e.g., at idle between
exposures, and while winding the shutter. However, the arrangement does
permit the artifact which is causing this thread.
    I would assume that the adjustable synch on my IIIf moves the
contact point 'ahead' so that the circuit completes before the lead
curtain ends its travel, providing the extra time needed for bulbs to
come to peak.

    So then, do I have it fundamentally right? Or, alternatively, am I
(fundamentally) all wet? :-) 
Stan Yoder
Pittsburgh