Thanks - yes I want to do some experimenting with dark frames & more post processing to improve the images when I get more time.
I would like to get a CHDK capable camera with a wider FOV than the A490/A495 (I have both) offers though. I have a Sony NEX-5N as well with a remote time-lapse / astrophotography trigger I can use too, but the Canon's are fun to tweak and experiment with.