Sony A9 has a
24.0MP Full frame (35.6 x 23.8 mm ) sized Stacked BSI-CMOS sensor and features BIONZ X processor. On the other hand, Sony A7S II has a
12.0MP Full frame (35.6 x 23.8 mm ) sized CMOS sensor and features Bionz X processor.
Sony A9's sensor provides 12MP more than Sony A7S II'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 A9 and A7S II sensor size comparison.
Sony A9 and Sony A7S II 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. On the other hand, since Sony A7S II has 99% larger pixel area (70.55µm2 vs 35.30µm2) compared to Sony A9, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
DxOMark Sensor Scores
Both Sony A9 and Sony A7S II 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, A9 has scored 92, 7 points higher than A7S II.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Sony A9 |
92 |
24.9 bits |
13.3 Evs |
3517 ISO |
Sony A7S II |
85 |
23.6 bits |
13.3 Evs |
2993 ISO |