Panasonic GF3 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine FHD processor. On the other hand, Olympus E-PL9 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VIII processor.
Below you can see the GF3 and E-PL9 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic GF3 and Olympus E-PL9 Cameras
Panasonic GF3 and Olympus E-PL9 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 Panasonic GF3 has 32% larger pixel area compared to Olympus E-PL9, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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
Panasonic GF3
or the
Olympus E-PL9 ,
including hyperfocal distance.