OM System OM-5 has a
20.0MP Four Thirds (17.4 x 13 mm ) sized CMOS sensor and features TruePic IX processor. On the other hand, Olympus E-M5 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VI processor.
Below you can see the OM-5 and E-M5 sensor size comparison.
Sensor Size and Resolution Comparison image of OM System OM-5 and Olympus E-M5 Cameras
OM System OM-5 and Olympus E-M5 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-5
or the
Olympus E-M5 ,
including hyperfocal distance.