Olympus E-620 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic III+ 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.
Olympus E-M1 II's sensor provides 8MP more than Olympus E-620'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.
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 E-620 and E-M1 II sensor size comparison.
Olympus E-620 and Olympus E-M1 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. Olympus E-620 and Olympus E-M1 II sensors have been tested by DxO and the results show that E-M1 II has a better overall score of 80, 25 points higher compared to E-620's score of 55.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Olympus E-620 |
55 |
21.3 bits |
10.3 Evs |
536 ISO |
Olympus E-M1 II |
80 |
23.7 bits |
12.8 Evs |
1312 ISO |