Both Nikon D5500 and Sony A77 have 24.0 MP resolution sensors but Nikon D5500's sensor is APS-C (23.5 x 15.6 mm ) and Sony A77's sensor is APS-C (23.5 x 15.6 mm ).
Since Sony A77's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Nikon D5500.
Another difference between these two cameras is that Nikon D5500'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 D5500 and A77 sensor size comparison.
Nikon D5500 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 D5500 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, D5500 has scored 84, 6 points higher than A77.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D5500 |
84 |
24.1 bits |
14.0 Evs |
1438 ISO |
Sony A77 |
78 |
24.0 bits |
13.2 Evs |
801 ISO |