Ricoh GR III has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor . On the other hand, Sigma DP2 Quattro has a
20.0MP APS-C (23.5 x 15.7 mm ) sized CMOS (Foveon X3) sensor and features TRUE III engine processor.
Another difference between these two cameras is that Ricoh GR III'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 GR III and DP2 Quattro sensor size comparison.
Sensor Size and Resolution Comparison image of Ricoh GR III and Sigma DP2 Quattro Cameras
Ricoh GR III and Sigma DP2 Quattro 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
Ricoh GR III
or the
Sigma DP2 Quattro ,
including hyperfocal distance.
