Both Nikon D200 and Canon 40D have APS-C sized 10.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the D200 and 40D sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D200 and Canon 40D Cameras
As seen above, Nikon D200 has a 1.1x Larger sensor area than Canon 40D. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Nikon D200
64
22.3 bits
11.5 Evs
583 ISO
Canon 40D
64
22.1 bits
11.3 Evs
703 ISO
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Nikon D200
or the
Canon 40D ,
including hyperfocal distance.
