Scott,
Re: Barnards loop in 10seconds...actually if you really contrast stretch the modified 300D will start to record Barnards loop in 10 seconds - just need to use a fast lens. See attached image which is 10 seconds @ f2 and ISO1600.
I have just uploaded a modified 300D shot of Orion, processed identically to Berts 5D shot. Field of view, ISO and focal ratio where the same as his shot - the important DIFFERENCE is the exposure is 3x longer for the 300D!
http://www.pbase.com/terrylovejoy/image/54146739
http://www.pbase.com/terrylovejoy/image/53965466
Happy new year all...16 minutes to go for us
Terry