Pentax K-S1 has a
20.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Prime MII processor. On the other hand, Pentax K-5 IIs has a
16.0MP APS-C (23.7 x 15.7 mm ) sized CMOS sensor and features Prime II processor.
Another similarity between these two cameras is that both Pentax K-5 IIs and Pentax K-S1 sensors lack anti-alias (Low-Pass) filters. 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-S1 and K-5 IIs sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-S1 and Pentax K-5 IIs Cameras
Pentax K-S1 and Pentax K-5 IIs 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. Pentax K-S1 and Pentax K-5 IIs sensors have been tested by DxO and the results show that K-5 IIs has a better overall score of 82, 4 points higher compared to K-S1's score of 78.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Pentax K-S1
78
23.5 bits
13.0 Evs
1061 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-S1
or the
Pentax K-5 IIs ,
including hyperfocal distance.
