Both Nikon D7100 and Sony A77 have APS-C sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another difference between these two cameras is that Nikon D7100's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the D7100 and A77 sensor size comparison.
Nikon D7100 and Sony A77 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.
DxOMark Sensor Scores
Both Nikon D7100 and Sony A77 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, D7100 has scored 83, 5 points higher than A77.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D7100 |
83 |
24.2 bits |
13.7 Evs |
1256 ISO |
Sony A77 |
78 |
24.0 bits |
13.2 Evs |
801 ISO |