Both Nikon D200 and Pentax K200D 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 K200D sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D200 and Pentax K200D Cameras
Nikon D200 and Pentax K200D have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the 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
Pentax K200D
64
22.4 bits
11.4 Evs
561 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
Pentax K200D ,
including hyperfocal distance.
