Nikon D90 has a
12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor . On the other hand, Sony A77 II has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz X processor.
Sony A77 II's sensor provides 12MP more than Nikon D90's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the D90 and A77 II sensor size comparison.
Nikon D90 and Sony A77 II 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 D90 and Sony A77 II sensors have been tested by DxO and the results show that A77 II has a better overall score of 82, 9 points higher compared to D90's score of 73.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D90 |
73 |
22.7 bits |
12.5 Evs |
977 ISO |
Sony A77 II |
82 |
24.4 bits |
13.4 Evs |
1013 ISO |