Both Panasonic GX850 and Pentax K-5 II have 16.0 MP resolution sensors but Panasonic GX850's sensor is Four Thirds (17.3 x 13 mm ) and Pentax K-5 II's sensor is APS-C (23.7 x 15.7 mm ).
Since Pentax K-5 II's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Panasonic GX850.
Another difference between these two cameras is that Panasonic GX850's sensor lacks 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 GX850 and K-5 II sensor size comparison.
As seen above, Pentax K-5 II has a 1.7x Larger sensor area than Panasonic GX850. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in 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. Panasonic GX850 and Pentax K-5 II sensors have been tested by DxO and the results show that K-5 II has a better overall score of 82, 9 points higher compared to GX850's score of 73.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Panasonic GX850 |
73 |
23.2 bits |
13.3 Evs |
586 ISO |
Pentax K-5 II |
82 |
23.8 bits |
14.1 Evs |
1235 ISO |