Olympus E-PM1 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VI processor. On the other hand, Panasonic GX8 has a
20.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor.
Panasonic GX8's sensor provides 8MP more than Olympus E-PM1'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 E-PM1 and GX8 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-PM1 and Panasonic GX8 Cameras
Olympus E-PM1 and Panasonic GX8 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 Olympus E-PM1 has 65% larger pixel area compared to Panasonic GX8, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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-PM1 and Panasonic GX8 sensors have been tested by DxO and the results show that GX8 has a better overall score of 75, 23 points higher compared to E-PM1's score of 52.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Olympus E-PM1
52
21.0 bits
10.3 Evs
499 ISO
Panasonic GX8
75
23.5 bits
12.6 Evs
806 ISO
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Olympus E-PM1
or the
Panasonic GX8 ,
including hyperfocal distance.
