Both Nikon D200 and Pentax K10D 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 K10D sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D200 and Pentax K10D Cameras
Nikon D200 and Pentax K10D 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
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Nikon D200 and Pentax K10D sensors have been tested by DxO and the results show that K10D has a better overall score of 66, 2 points higher compared to D200's score of 64.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Nikon D200
64
22.3 bits
11.5 Evs
583 ISO
Pentax K10D
66
22.7 bits
11.6 Evs
522 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 K10D ,
including hyperfocal distance.
