Olympus E-520 has a
10.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor . On the other hand, Olympus E-620 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic III+ processor.
Below you can see the E-520 and E-620 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-520 and Olympus E-620 Cameras
Olympus E-520 and Olympus E-620 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-520 has 22% larger pixel area compared to Olympus E-620, 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-520
55
21.4 bits
10.4 Evs
548 ISO
Olympus E-620
55
21.3 bits
10.3 Evs
536 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-520
or the
Olympus E-620 ,
including hyperfocal distance.