Nikon D3100 has a
14.0MP APS-C (23.1 x 15.4 mm ) sized CMOS sensor and features Expeed 2 processor. On the other hand, Sony A57 has a
16.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor .
Below you can see the D3100 and A57 sensor size comparison.
Nikon D3100 and Sony A57 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. Nikon D3100 and Sony A57 sensors have been tested by DxO and the results show that A57 has a better overall score of 75, 8 points higher compared to D3100's score of 67.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D3100 |
67 |
22.5 bits |
11.3 Evs |
919 ISO |
Sony A57 |
75 |
23.4 bits |
13.0 Evs |
785 ISO |