Both Sony A65 and Nikon D3200 have APS-C sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the A65 and D3200 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A65 and Nikon D3200 Cameras
Sony A65 and Nikon D3200 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. Sony A65 and Nikon D3200 sensors have been tested by DxO and the results show that D3200 has a better overall score of 81, 7 points higher compared to A65's score of 74.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A65
74
23.4 bits
12.6 Evs
717 ISO
Nikon D3200
81
24.1 bits
13.2 Evs
1131 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 A65
or the
Nikon D3200 ,
including hyperfocal distance.
