Nikon D3200 has a
24.0MP APS-C (23.2 x 15.4 mm ) sized CMOS sensor and features Expeed 3 processor. On the other hand, Pentax K-S2 has a
20.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features PRIME MII processor.
One other difference between these two cameras that is worth mentioning is that Pentax K-S2'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 D3200 and K-S2 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D3200 and Pentax K-S2 Cameras
Nikon D3200 and Pentax K-S2 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
Nikon D3200
or the
Pentax K-S2 ,
including hyperfocal distance.
