Both Sony FX30 and Ricoh GR IV have APS-C sized 26.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
One other difference between these two cameras that is worth mentioning is that Ricoh GR IV'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 FX30 and GR IV sensor size comparison.
Sensor Size and Resolution Comparison image of Sony FX30 and Ricoh GR IV Cameras
Sony FX30 and Ricoh GR IV have the same sensor sizes so they will provide same level of control over the depth of field when used with 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
Sony FX30
or the
Ricoh GR IV ,
including hyperfocal distance.
