Both Sony A230 and Sony A200 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 A230 and A200 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A230 and Sony A200 Cameras
Sony A230 and Sony A200 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
Sony A230
63
22.3 bits
11.4 Evs
531 ISO
Sony A200
63
22.3 bits
11.3 Evs
521 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
Sony A230
or the
Sony A200 ,
including hyperfocal distance.