Both Olympus E-PM1 and Panasonic GF2 have Four Thirds sized 12.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the E-PM1 and GF2 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-PM1 and Panasonic GF2 Cameras
Olympus E-PM1 and Panasonic GF2 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.
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 GF2 sensors have been tested by DxO and the results show that GF2 has a better overall score of 54, 2 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 GF2
54
21.2 bits
10.3 Evs
506 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 GF2 ,
including hyperfocal distance.
