Thanks for your input guys.
I am not new to astrophotography, but certainly not an expert. I use a GStarEX2 ( a high sensitivity but unfortunately low res. camera) and my Nikon D90 DSLR. I do want to advance though and am looking at getting a ZWO ASI1600MM sometime soon. I'm particularly interested in narrow-band imaging. So, all that being said, I'm going for my 1st choice - The Astrophotography Manual, A Practical and Scientific Approach to Deep Space Imaging, by Chris Woodhouse. Thanks again for your replies and advice.
Robert
