Pentax 645D has a
40.0MP Medium format (44 x 33 mm ) sized CCD sensor and features Prime II processor. On the other hand, Sony A99 II has a
42.0MP Full frame (35.9 x 24 mm ) sized BSI-CMOS sensor and features Bionz X processor.
Another similarity between these two cameras is that both Sony A99 II and Pentax 645D 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 645D and A99 II sensor size comparison.
As seen above, Pentax 645D has a 1.7x Larger sensor area than Sony A99 II. 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. Pentax 645D and Sony A99 II sensors have been tested by DxO and the results show that A99 II has a better overall score of 92, 10 points higher compared to 645D's score of 82.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Pentax 645D |
82 |
24.6 bits |
12.6 Evs |
1262 ISO |
Sony A99 II |
92 |
25.4 bits |
13.4 Evs |
2317 ISO |