Leica SL3-S has a
24.0MP Full frame (36 x 24 mm ) sized BSI-CMOS sensor and features Maestro IV processor. On the other hand, Olympus E-M1 III has a
20.0MP Four Thirds (17.4 x 13 mm ) sized CMOS sensor and features TruePic IX processor.
Another similarity between these two cameras is that both Olympus E-M1 III and Leica SL3-S sensors lack anti-alias (Low-Pass) filters. 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 SL3-S and E-M1 III sensor size comparison.
Sensor Size and Resolution Comparison image of Leica SL3-S and Olympus E-M1 III Cameras
As seen above, Leica SL3-S has a 3.8x Larger sensor area than Olympus E-M1 III. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in 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
Leica SL3-S
or the
Olympus E-M1 III ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(Full frame versus Four Thirds),
so compare them at the same framing rather than the same focal length.
Put the same focal length on the smaller sensor and it will show less depth of
field, not more, because it also crops tighter. The calculator shows the
full frame equivalent focal length for each body so you can match the framing.