Originally Posted by M_Six
I took two identical shots, one with the 7D and one with the T1i. Both with the 35mm lens at F2, ISO100, and 1/125. These were shot just a few seconds apart (the time it took to swap the lens over). These are 640x480 100% crops. The T1i fares well against the 7D, but the 7D had lighter exposure for the same shot. Just a pixel number or pixel pitch thing?
If these are in-camera jpegs they don't mean a thing, other than the processors are programmed slightly differently for the different sensors. Shoot RAW and convert to jpegs with the same settings. Even if they're a little different, you can always adjust during RAW conversion.
The T2i shares the sensor with the 7D, but with the T1i I think that you have a higher pixel-pitch (larger pixels). Where the 7D shines is taking something very detailed and looking at it at 200%. It'll resolve more detail than most of Canon's other cameras.