Olympus E-P1 has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic V processor. On the other hand, Panasonic GH5S has a
10.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine 10 processor.
One other difference between these two cameras that is worth mentioning is that Panasonic GH5S's sensor doesn't have an 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 E-P1 and GH5S sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-P1 and Panasonic GH5S Cameras
Olympus E-P1 and Panasonic GH5S 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 GH5S has 20% larger pixel area (22.14µm 2 vs 18.45µm 2 ) compared to Olympus E-P1, it has larger pixel area to collect light hence potential to 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
Olympus E-P1
or the
Panasonic GH5S ,
including hyperfocal distance.
