Useful replies so far, thanks.

winensky: I'm using a Canon dSLR through my telescope (Celestron NexStar 8" GPS) for the deep sky objects, mainly. The camera is capable of up to 30 seconds exposures, but, unfortunately, lacks a setting allowing me to keep the shutter open for an extended period of time without a remote.

As far as other (moon, planet) shots go, I've been using a CCD imager with registax, though I did not know that I could stack JPEG images in there as well, I suspect that I've been blind.

That's just the sort of information I needed, though, and I'll be sure to try using registax next chance I get for stacking regular images.

Thanks!