Olympus E-510 has a
10.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor . On the other hand, Olympus E-PM1 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VI processor.
Below you can see the E-510 and E-PM1 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-510 and Olympus E-PM1 Cameras
Olympus E-510 and Olympus E-PM1 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-510 has 22% larger pixel area compared to Olympus E-PM1, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Olympus E-510
52
21.2 bits
10.0 Evs
442 ISO
Olympus E-PM1
52
21.0 bits
10.3 Evs
499 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-510
or the
Olympus E-PM1 ,
including hyperfocal distance.