OK, I have heard many times about BackyardEOS for controlling Canon EOS cameras used in Astrophotography.  Unfortunately my 1st generation Digital Rebel (300D) with its now ancient DIGIC-I processor is not a supported platform.  Even though it does have USB and you can trigger the shutter through that you can only use the predefined exposure lengths up to 30 seconds.  You cannot use Bulb mode through the USB port, only through the 2.5mm phono plug.  The 300D only has USB 1.1 so even if you could hold the shutter open indefinitely, downloading a full raw image would take an age.  Added functionality in the DIGIC-II and greater processors includes things like sub-frames and live view which lets you do lovely things like live preview for frame and focus.  I didn’t realize how incredibly useful that was until I borrowed my mom’s 1100D and tried BackyardEOS out for myself.  Let me tell you, that is WONDERFUL.  I didn’t get to experiment with the drift alignment routine in BYEOS but if it is even as simple as the parallel crosshair it is a useful tool indeed.  BackyardEOS is a complete bargain for $30, $38 if you want to use ASCOM to control the focuser.  What’s that ASCOM plugin all about?  Well, if you have an ASCOM compliant focuser and the appropriate drivers on your PC, BYEOS can do all the FWHM auto-focus thing for you so all you do is find a nice star to focus on and press GO!  Then magic happens and your image is focused for you.  Fan-frickin-tastic!  Great stuff that BYEOS

Backyard EOS