Ok - Thought I would post this to show why it's not a good idea to use an Unmodified EOS DSLR for Deep Sky work on objects rich in Ha. Basically the filter in front of the CCD on EOS blocks about 90% of available Ha... It is possible to remove the filter but I'm not sure about ripping my EOS to bits..
Anyway image is 1hr 20mins on North American in 3min subs ISo 400. There was a full moon near by & it was night before Bonfire night so was a bit hazy... I guess from a dark site & higher ISO it might be better but not a lot to show for 1hr 20min...
Cheers, John
(http://homepage.ntlworld.com/john.punnett/graphics/oas/Na_colour2.jpg)