Both Sony A380 and Nikon D3100 have APS-C sized 14.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the A380 and D3100 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A380 and Nikon D3100 Cameras
Sony A380 and Nikon D3100 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 A380
67
22.6 bits
11.8 Evs
614 ISO
Nikon D3100
67
22.5 bits
11.3 Evs
919 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 A380
or the
Nikon D3100 ,
including hyperfocal distance.
