Hi Steve,
Thanks for those pointers.
Looks like I've got a lot of learning to do - I had not heard of DSS prior to your mentioning it. I googled it and see what it is for (I have been using Photoshop for stacking images).
What do you mean by flat and darks, though?
Have you done any imaging using a 2x teleconverter between the camera and the t-ring? It doubles your focal length, and I was using that with an old Nikon D60 and a 500mm lens (effective 1500mm once you consider the 1.5x focal length multiplier of the CX sensor inside the camera) - that was good for imaging NGC 1514 despite only using an ordinary camera tripod and no tracking. Check out the second-last photograph in this blog post:
http://astro.huntergeophysics.com/catching-up-on-2012/
I am hoping that idea will work with the telescope as well, as the result will be a focal length of 1800mm!
Thanks again,
David