...or if you are using a Canon DSLR (T2i) and it supports Magic Lantern - you can install that firmware and turn on the intervalometer and just let it go taking images every so many seconds. Works great, it is one less thing to think about as you are flying. ...or if you have a camera that supports continuos shots while pressing the button, you can put an elastic band over the button with a round eraser and simulate holding down the button, I have used that as well (probably works better with slower cameras (frame rates) so you don't fill up your memory card.