Both Pentax K-S2 and Panasonic GX9 have 20.0 MP resolution sensors but Pentax K-S2's sensor is APS-C (23.5 x 15.6 mm ) and Panasonic GX9's sensor is Four Thirds (17.3 x 13 mm ).
Since Pentax K-S2's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Panasonic GX9.
Another similarity between these two cameras is that both Panasonic GX9 and Pentax K-S2 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 K-S2 and GX9 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-S2 and Panasonic GX9 Cameras
As seen above, Pentax K-S2 has a 1.6x 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
Pentax K-S2
or the
Panasonic GX9 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(APS-C 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.
