So here is my totally unscientific look at  Canon 40D vs. Orion Star Shoot Pro   I normally use an Orion ED 80 APO refractor for imaging. As it turns out another happy Astro Acres user had a matching OTA. How convenient. Through much cajoling he was convinced to  let me borrow he baby for a few nights. I have a mounting bracket on my Orion Atlas mount that can accommodate 3 OTA's at once So I setup the 2 Orion ED80s and the Orion Short Tube 80 Guide scope all together. I was able to shoot Simultaneous images of the same exposure and at the same conditions. IE seeing , temperature , guiding consistency., and what not. You know how this astro photo stuff is. Lots or variables. 

Well I picked three convenient objects that I liked but still they were different enough to test various attributes of the cameras. I chose M31 because it is huge and bright. The core always blows out so that would test the blooming or saturation . It also has a little faint color in the edges of the arms that is hard to get. And the dust lanes would be a test for contrast. I shot M33 because it is much fainter but still huge-ish.   And I  shot the Horsehead because it is a nebula and not a galaxy. But mostly because it is the coolest thing in the Whole Universe. IMHO.

I stacked various numbers of frames to see how the noise varied. And I used Maxim for all of the Image processing for consistency.   I shot series of 180seconds  300 seconds and 600seconds. I used mostly the 600 second sets because. Duh, they always look the best. The 180 and 300 were dimmer. I really don't know why I mess with the shorter exposures. I shot all of the DSLR image at ISO 800. You can click on any image to get a larger version.  A word of warning. I left he images at full resolution and quality. Some of them are several megs each. They may take a while to load. But I figured this is a pixel peeking exercise so there you have it.

That said here's the poop. 

10 Mega pixels

14 bit

6 Mega pixels

16 bit