Resolution comparison 40D vs 50D vs 7D


The target is  a Canadian twenty dollar bill taped to a wall. Cameras 40D, 50D and 7D were  used to shoot the target with with 300mm f2.8L IS (IS off) lens at f8 distance 2.58 meters, tripod, bounce flash manual power. Shutter 1\250, ISO 160. Ambient light did not contribute to the exposure. 

I shot several images with each camera using live view  to manually focus. There  were slight focus variations due to the difficulty of manually focusing the 300 f2.8 so only the sharpest frame was selected from each camera for the side by side comparison.

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, daylight color balance.

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 image show here is a JPG with low compression.

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




Test target


 
 
 
 

Actual pixels normalized from the above target crop


 
 

Conclusion:
The 7D images show slightly more detail than the 50D and significantly more than the 40D. 
 
 

Comments;

1 - The same test performed at f5.6 produced similar results.
2 - It is clear that slight focusing differences from frame to frame can easily influence the results.
3 - I have also sharpened these images and compared them side by side and the results are the same, the 7D has slightly more detail than the 40 and 50D.
 

 
 
 
 

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