Both Canon 1D X III and Canon 1D X II have Full frame sized 20.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the 1D X MIII and 1D X MII sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 1D X III and Canon 1D X II Cameras
Canon 1D X III and Canon 1D X II 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.
DxOMark Sensor Scores
Both Canon 1D X III and Canon 1D X II sensors have been tested by DxoMark. DxoMark scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Of the two cameras that we are comparing, 1D X MIII has scored 91, 3 points higher than 1D X MII.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 1D X III
91
24.2 bits
14.5 Evs
3248 ISO
Canon 1D X II
88
24.1 bits
13.5 Evs
3207 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
Canon 1D X III
or the
Canon 1D X II ,
including hyperfocal distance.
