Nikon Z6 III has a
24.0MP Full frame (35.9 x 23.9 mm ) sized Partially-Stacked CMOS sensor and features Expeed 7 processor. On the other hand, Panasonic GX9 has a
20.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor.
One other difference between these two cameras that is worth mentioning is that Panasonic GX9'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 Z6 Mark III and GX9 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon Z6 III and Panasonic GX9 Cameras
As seen above, Nikon Z6 III has a 3.8x Larger sensor area than Panasonic GX9. 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
Nikon Z6 III
or the
Panasonic GX9 ,
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.