Pentax K20D has a
15.0MP APS-C (23.4 x 15.6 mm ) sized CMOS sensor . On the other hand, Samsung NX20 has a
20.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor .
Samsung NX20's sensor provides 5MP more than Pentax K20D'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 K20D and NX20 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K20D and Samsung NX20 Cameras
Pentax K20D and Samsung NX20 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 K20D and Samsung NX20 sensors have been tested by DxO and the results show that NX20 has a better overall score of 75, 10 points higher compared to K20D's score of 65.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Pentax K20D
65
22.9 bits
11.1 Evs
639 ISO
Samsung NX20
75
23.4 bits
12.9 Evs
785 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 K20D
or the
Samsung NX20 ,
including hyperfocal distance.
