Both Pentax K-5 II and Pentax K-5 IIs have APS-C sized 16.0 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-5 IIs'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 K-5 II and K-5 IIs sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-5 II and Pentax K-5 IIs Cameras
Pentax K-5 II and Pentax K-5 IIs 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
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Pentax K-5 II
82
23.8 bits
14.1 Evs
1235 ISO
Pentax K-5 IIs
82
23.9 bits
14.1 Evs
1208 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-5 II
or the
Pentax K-5 IIs ,
including hyperfocal distance.
