On Thu, Feb 15, 2001 at 12:33:10AM -0000, Bob Talbot wrote:
> With EOS cameras, would splicing two remote release plugs on to one
> switch work, or would I be in danger of shorting something between the
> two cameras?
> IE: is getting them both to fire *now* , together trivial or does it
> need more thought?
>
> Anyone know the inner workings ?
I've examined my 60T3 and the characteristics of the remote socket on my 620s
for exactly the same purpose.
Here is what I've found.
60T3:
The cable has three leads: common (shield), half-press (white), and shutter
release (red). When you press the button half way, the half-press and common
leads are connected together. When you press it the rest of the way, all three
are connected together.
EOS620:
Voltages are taken with a new 6.5 battery in the camera.
The half-press contact is initially at 4.5V, with impedance of 2M.
Contact is registered when a load across the contacts drops below about 10K,
with the voltage at that point being about 20mV. This activates the camera,
and the voltage with a 10K load then jumps to 0.85V, open circuit to 5.3V, and
the camera impedance drops to about 43K.
The full-press contact has 7K impedance, and initially 5.3V.
It triggers at 1.8V, produced by a 3.2K load.
The half-press contact does not need to be closed first for this lead to
trigger the camera, but it may not get the right exposure if you do that -
haven't tested that.
Voltages are present at the remote release contacts even when the camera is
off.
The relatively high impedances suggest to me that simple ganging cameras on a
single remote will *probably* work, and in any case it's unlikely to damage the
cameras. They should probably be disconnected from each other whenever the
cameras are off.
I intend to test it after I pick up another cable to cannibalize. In the worst
case, it would require a simple circuit to trigger the two cameras while
keeping them isolated.
John
--
John DuBois [EMAIL PROTECTED] KC6QKZ/AE http://www.armory.com./~spcecdt/
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
