The target is  a grid pattern on paper. Cameras 40D, 50D and 7D were all used to shoot the target with one shot AF mode, Mirror lock up, 2 second timer and tripod with 300mm f2.8L IS (IS off) lens at f5.6 distance 2.97 meters.

I shot several images with each camera with autofocus and one shot mode, offsetting the focus manually and letting the auto focus refocus for each shot. There is variation due to slight focusing errors so I also shot some frames focused manually and slide the camera lens mount through the clamp 1 mm at a time. I then selected the sharpest image from each camera for the side by side comparison image. 

The 40D and 50D images were processed with a  Breezebrowser conversion from RAW to TIF and the 7D was converted with DPP (both use Canon conversion engines). No sharpening or noise reduction was used. Picture style was set to Standard, 8bit TIF, adobeRBG.

Corel Paint Shop Pro Smart resize method was used to resize the 40D and 50D images to 5184 pixels long side to match the resolution of the 7D. No sharpening or noise reduction was used.

The side by side  comparison is at actual pixels. The image show here is a JPG with low compression.

These results are representataive of what  I have found with past testing.