OM System OM-3 has a
20.0MP Four Thirds (17.4 x 13 mm ) sized Stacked BSI Live MOS Sensor sensor and features TruePic X Dual Quad Core 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.
Another difference between these two cameras is that OM System OM-3's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the OM-3 and E-PL9 sensor size comparison.
Sensor Size and Resolution Comparison image of OM System OM-3 and Olympus E-PL9 Cameras
OM System OM-3 and Olympus E-PL9 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
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
OM System OM-3
or the
Olympus E-PL9 ,
including hyperfocal distance.
