I've used Magic Lantern's Intervalometer set to every 15 seconds with my exposure time of 15 seconds and it works for me. It'll continue to fire constantly. I'm using a 600D with my lens at 17mm and 15 second exposures so I can have a still image if I want or time-lapse the footage or stack them in post. I stopped this sequence rather early due to sand-flies biting. https://www.facebook.com/photo.php?fbid=10151624114128719&set=a.10150261755648719.332147.122503888718&type=1&theater