I've been shooting some timelapse with a T2i using an off-brand intervalometer. A coworker, who also has a T2i and I were discussing creating a 3D timelapse. The issue of firing the cameras simultaneously arose. So, the question for the board is... what methods are you using to fire two cameras and or, can you point me towards information regarding how to alter my intervalometer so it will control two cameras?

thanks!

If you want to play it safe, it would pay to go through an electrical isolation circuit, eg opto-isolator.
I have done it by just wiring up a splitter cable to run off my normal intervalometer though.

Thanks Antz. I'll have to do a google search to understand what an opto-isolator is. In the meantime, was the splitter something off the shelf, or did you have to make it yourself? (I'm not really electrically inclined, if that's not obvious).

You could get an RF-602 transmitter and 2 RF-602 receivers (or the new RF-603 transceivers). Have your intervalometer go into the Tx, and the receivers on the cameras to trigger them both simultaneously.

I've done this before when triggering multiple cameras. They're cheap enough, and WAY more reliable than the other cheap Chinese triggers. I've never had a flash misfire using RF-602 gear (even shooting @ 8fps), and I've used them up to about 100ft away through two thick concrete walls with no issues (manufacturer claims much further than this, but I haven't had a need to test personally).

An optoisolator is a LED and (usually) phototransistor pair inside an IC. When you send current to the LED side, it completes the circuit on the other side because the phototransistor's seeing light from the LED (you can't see it, as it's all inside a little 4, 6 or 8 pin chip). Basically it optically isolates one circuit (your intervalometer) from another circuit (your camera(s)) so that current doesn't flow between them.

There's more on optoisolators/photocouplers/optocouplers (there's a million names for 'em), on the OpenMoco basic arduino intervalometer page.

http://openmoco.org/node/88

You'd just replace the Arduino with your own intervalometer going into the optoisolator.

I went out and splasehed out on 2 Giga T Pro 11 wireless transmitters today and have just returned from shooting a 3D timelapse here in Sydney on the 5D's worked a treat..