Pentax K-70 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features PRIME MII processor. On the other hand, Sony A58 has a
20.0MP APS-C (23.2 x 15.4 m ) sized CMOS sensor .
Another difference between these two cameras is that Pentax K-70's sensor lacks 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 K-70 and A58 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-70 and Sony A58 Cameras
Pentax K-70 and Sony A58 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
Pentax K-70
or the
Sony A58 ,
including hyperfocal distance.
