Both Canon 80D and Pentax K-3 II have APS-C sized 24.0 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 Pentax K-3 II'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 80D and K-3 II sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 80D and Pentax K-3 II Cameras
Canon 80D and Pentax K-3 II 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
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It 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. Canon 80D and Pentax K-3 II sensors have been tested by DxO and the results show that K-3 II has a better overall score of 80, 1 points higher compared to 80D's score of 79.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 80D
79
23.6 bits
13.2 Evs
1135 ISO
Pentax K-3 II
80
23.6 bits
13.6 Evs
1106 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 80D
or the
Pentax K-3 II ,
including hyperfocal distance.
