I just completed a little project which will be absolutely great to use for photographing the critters that frequent our back yard or taking photos of a group with me in it.
What I built is a circuit that will allow me to make the camera take a photo (or even a whole lot of them) remotely using my Elinchrom EL Skyport universal remote radios.
The EL Skyports were designed to trigger studio flash units, and they do that extremely well. However, they will not trigger my 20D directly. There are a couple of problems, not the least of which is the interactivity between the "half-press" and "full-press" of the shutter release button (or the circuits for them that a remote switch activates).
I tried all sorts of simplistic methods such as a pair of diodes to isolate the two switch circuits, but nothing worked. The circuit I designed closed the "half-press" circuit for about 65 milliseconds and then closes the "full-press" circuit for a little longer than that.
The beauty of this setup is that is will wake up a "sleeping" 20D with a single press of the transmitter's "test" button, and I can do it from up to about 300 feet from the camera.
To see the schematic, go post #52 of this thread where you'll find a lot more discussion about this subject.
