From: Bob Sull <[EMAIL PROTECTED]>
Subject: Re: EOS vivitar 283 and 285
>There was a way of measuring trigger voltage and what an
>EOS body can handle without braking posted quite some
>time ago. Maybe someone can post it if they remember.
It's easy. Get a voltmeter ("DVM," "VTVM," "VOM," or "multimeter").
Get the flash unit, leave it off the camera, turn it on, let it
charge up. Measure the voltage from the side contact of the
shoe to the center contact. I'm not sure, but I think the center
contact will be positive. If your meter has manual range switching,
start out with a range that shows 80 volts or so and switch downward
as necessary
If the resulting voltage is over 20, it can be dangerous to modern
cameras with transistors that do the flash triggering. Older cameras
with metallic contacts didn't really care, although their life could be
shortened by flash units dumping excessive current during the
triggering process.
NOTE: I do not recall the exact voltage that Canon states is dangerous
to the triggering circuits in their EOS cameras. Someone on this list
(Dave Herzstein, maybe?) does. And of course that's what the
auxiliary shoe-mount trigger boosters such as the one from Nikon
are designed to handle. They're solid state, but their trigger devices
are specified to withstand the 80-100 volts that older flashes put
on their trigger terminals.
DGW
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