Hi Mr. Sully,
Thanks for that link. It is a very interesting article. That guy has taken some beautiful shots and really favors the Nikon cameras. What I have found is that the longer you are able to track and expose the light to your sensor the lower you can go with the ISO and less noise your picture will have. Shooting deep space objects at 60 or 90 seconds like I am doing requires the higher ISO's to even begin to see any details in the them.
This has stirred my curiosity though to prove or disprove my point. I have been wanting to gather more data on M1 so the next clear night I will shoot for 1 hour at 800 and 1 hour at 1600 ISO and compare those stacked shots with my previous shot at 3200. ( I started setting up tonight but clouds began to roll in from Spiral's neck of the woods! (Tennessee))