Samsung NX20 has a
20.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor . On the other hand, Pentax K-m has a
10.0MP APS-C (23.5 x 15.7 mm ) sized CCD sensor .
Samsung NX20's sensor provides 10MP more than Pentax K-m's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the NX20 and K-m sensor size comparison.
Sensor Size and Resolution Comparison image of Samsung NX20 and Pentax K-m Cameras
Samsung NX20 and Pentax K-m 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. On the other hand, since Pentax K-m has 98% larger pixel area (36.75µm 2 vs 18.48µm 2 ) compared to Samsung NX20, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
DxOMark Sensor Scores
Both Samsung NX20 and Pentax K-m 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, NX20 has scored 75, 11 points higher than K-m.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Samsung NX20
75
23.4 bits
12.9 Evs
785 ISO
Pentax K-m
64
22.4 bits
11.4 Evs
513 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
Samsung NX20
or the
Pentax K-m ,
including hyperfocal distance.
