a Time-Lapse Shutter Release

I plan to post again with the schematics and the math, but today I finished:

This circuit connects to all my other remote shutter peripherals. I used a 555 timer to generate the timing, and two potentiometers - one for on-time/exposure, one for off-time. Add the times together to see the times between shots. I also used a transistor, as the 555 generates an active-high pulse, and the Canon releases use a current-short to take photos.