I use one like that. You might not need it if you're willing to try the Magic Lantern firmware. It works great on my 550D. I usually use my Canon G10 for timelapses. There's the CHDK hack for that. The shutter seems to last longer than with DSLR's, I can take photos with my main camera while doing timelapses and there's less noticeable flicker. There is the slightly turning the lens trick with Canon DSLR's but I find it easier to have my G10 setup and ready to go.