Both Nikon D200 and Sony A300 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 A300 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D200 and Sony A300 Cameras
Nikon D200 and Sony A300 have the same sensor sizes so they will provide same level of control over the depth of field when used with 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
Sony A300
64
22.5 bits
11.4 Evs
538 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
Sony A300 ,
including hyperfocal distance.
