Both Pentax K-m and Nikon D80 have APS-C sized 10.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the K-m and D80 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-m and Nikon D80 Cameras
Pentax K-m and Nikon D80 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
Both Pentax K-m and Nikon D80 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-m has scored 64, 3 points higher than D80.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Pentax K-m
64
22.4 bits
11.4 Evs
513 ISO
Nikon D80
61
22.1 bits
11.2 Evs
524 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-m
or the
Nikon D80 ,
including hyperfocal distance.
