Sony A55 has a
16.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz processor. On the other hand, Nikon D3100 has a
14.0MP APS-C (23.1 x 15.4 mm ) sized CMOS sensor and features Expeed 2 processor.
Below you can see the A55 and D3100 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A55 and Nikon D3100 Cameras
Sony A55 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
Both Sony A55 and Nikon D3100 sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, A55 has scored 73, 6 points higher than D3100.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A55
73
23.0 bits
12.4 Evs
816 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 A55
or the
Nikon D3100 ,
including hyperfocal distance.
