Both Canon S120 and Canon G15 have 1/1.7-inch sized 12.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the S120 and G15 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon S120 and Canon G15 Cameras
Canon S120 and Canon G15 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 S120 and Canon G15 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, S120 has scored 56, 10 points higher than G15.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon S120
56
21.3 bits
11.9 Evs
246 ISO
Canon G15
46
19.9 bits
11.5 Evs
165 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 S120
or the
Canon G15 ,
including hyperfocal distance.
