Sony A99 has a
24.0MP Full frame (35.8 x 23.8 mm ) sized CMOS sensor and features Bionz processor. On the other hand, Olympus E-M1 II has a
20.0MP Four Thirds (17.4 x 13 mm ) sized CMOS sensor and features TruePic VIII processor.
One other difference between these two cameras that is worth mentioning is that Olympus E-M1 II'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 A99 and E-M1 II sensor size comparison.
As seen above, Sony A99 has a 3.8x Larger sensor area than Olympus E-M1 II. 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 A99 and Olympus E-M1 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, A99 has scored 89, 9 points higher than E-M1 II.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Sony A99 |
89 |
25.0 bits |
14.0 Evs |
1555 ISO |
Olympus E-M1 II |
80 |
23.7 bits |
12.8 Evs |
1312 ISO |