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. On the other hand, Ricoh GR IIIx HDF has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor .
One other difference between these two cameras that is worth mentioning is that Ricoh GR IIIx HDF'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 DP2 Quattro and GR IIIx HDF sensor size comparison.
Sensor Size and Resolution Comparison image of Sigma DP2 Quattro and Ricoh GR IIIx HDF Cameras
Sigma DP2 Quattro and Ricoh GR IIIx HDF 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
Sigma DP2 Quattro
or the
Ricoh GR IIIx HDF ,
including hyperfocal distance.
