Both Pentax K-3 and Canon M3 have APS-C sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another difference between these two cameras is that Pentax K-3's sensor lacks 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 K-3 and M3 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-3 and Canon M3 Cameras
As seen above, Pentax K-3 has a 1.1x Larger sensor area than Canon M3. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
DxOMark Sensor Scores
Both Pentax K-3 and Canon M3 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, K-3 has scored 80, 8 points higher than M3.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Pentax K-3
80
23.7 bits
13.4 Evs
1216 ISO
Canon M3
72
22.8 bits
11.8 Evs
1169 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
Pentax K-3
or the
Canon M3 ,
including hyperfocal distance.
