If I didn’t have XBee’s kicking around from some other fanciful endeavour I probably would’ve purchased an inexpensive Aputure remote trigger for the photobooth at my wedding reception — but instead I decided to make an RF camera trigger system from parts I had around, mainly two XBees and a relay. XBee’s are great little wireless mesh transmitter/receivers, much like Tomax and Xamot what you do to one is instantly reflected by the other, so you need only connect a pin to high on the transmitting XBee and the same pin on the receiving XBee will go high — perfect for remotely triggering a relay.
The plan was to have one XBee with a simple pull-down button which would trigger a relay on the receiving XBee and whaddya know — it worked. The receiver relay was attached to a wired camera remote (Canon TC-80N3) I already had from a previous project which allowed the relay to trigger both a Canon Rebel XT and, after splicing in the original connector, a Canon 5D Mark II.
With this setup, two AA batteries for both the transmitter and receiver lasted for days. The only issue I found was that the Rebel XT needed about a 500 millisecond signal whereas the 5D Mark II would trigger instantly on a contact of any duration, I thought about a capacitor, timed-delay relay or 555 solution to keep the relay open longer, but never got around to implementing any solution — after all the 5D would capture the shot if not both cameras.
To be honest, this project survived to the night before, but I decided to scrap the photobooth entirely from the wedding reception to reduce complexity — the lighting turned out to be insufficient and, as the groom, I had no time left to deal with the camera setup. That being said, the theory is sound and it worked quite well for days in my living room, taking shot after shot of me and my fiancée lounging on our couch.