Both Sony A7 III and Canon R3 have Full frame sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the A7 III and R3 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A7 III and Canon R3 Cameras
Sony A7 III and Canon R3 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.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A7 III
96
25.0 bits
14.7 Evs
3730 ISO
Canon R3
96
25.0 bits
14.7 Evs
4086 ISO
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 A7 III
or the
Canon R3 ,
including hyperfocal distance.
