Found a really cheap solution for hands-free operation. Introducing the handy TI-83 graphing and programmable calculator (emphasis on programmable). Told about this link regarding time lapse photography while surfing for a commercial solution. A good colleague turned me onto this; Geoff is a real jack-of-all-trades sort. Turns out the remote shutter jack on my Rebel XT camera is a 2.5mm audio jack. The data port on the TI-83 is also a 2.5mm audio jack. By programming a routine to time mirror lock up and shutter release, the TI-83 send() command is used to pulse the data line...the same way a remote shutter control pulses the camera. The only difficulty I encountered was locating a male-to-male 2.5mm cable. Only thing I could find was online at BoxWave.
This is so cool! As I type this, the camera is outside working on 200 exposures of M17 tonight. No need for a laptop and cabling, now I'm free to grab the binoculars, star map, a beer, or two. The picture below is a little fuzzy, but you can see my messages printing to the screen as it operates the shutter release.
I programmed the calculator with the following:
[7/13/2008] Thanks to Craig on Andy's Shot Glass site, I've corrected listing. You MUST use the programs menu to enter commands, and remember to use the STO key to assign values to variables (the -> notation):