Both Sony A7 and Nikon D5500 have 24.0 MP resolution sensors but Sony A7's sensor is Full frame (35.8 x 23.9 mm ) and Nikon D5500's sensor is APS-C (23.5 x 15.6 mm ).
Since Sony A7'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.
One other difference between these two cameras that is worth mentioning is that Nikon D5500's sensor doesn't have an 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 A7 and D5500 sensor size comparison.
As seen above, Sony A7 has a 2.3x Larger sensor area than Nikon D5500. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
DxOMark Sensor Scores
Both Sony A7 and Nikon D5500 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, A7 has scored 90, 6 points higher than D5500.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Sony A7 |
90 |
24.8 bits |
14.2 Evs |
2248 ISO |
Nikon D5500 |
84 |
24.1 bits |
14.0 Evs |
1438 ISO |