Quote Originally Posted by KeVancity
40d has better iso performance than the 50d, let alone the T1i. The pixels are smaller on 50d to fit them all in - hence more noise.

That is a common misconception:


Myth busted: smaller pixels have more noise, less dynamic range


Specifically, here is a link demonstrating that the 50D has the same "ISO performance" as the 40D:


http://forums.dpreview.com/forums/read.asp?forum=1018&message=30211624