Pentax 645D has a
40.0MP Medium format (44 x 33 mm ) sized CCD sensor and features Prime II processor. On the other hand, Canon 5D MIII has a
22.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Digic 5+ processor.
Pentax 645D's sensor provides 18MP more than Canon 5D MIII'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.
Another difference between these two cameras is that Pentax 645D'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 645D and 5D MIII sensor size comparison.
As seen above, Pentax 645D has a 1.7x Larger sensor area than Canon 5D MIII. 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
Both Pentax 645D and Canon 5D MIII 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, 645D has scored 82, 1 points higher than 5D MIII.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Pentax 645D |
82 |
24.6 bits |
12.6 Evs |
1262 ISO |
Canon 5D MIII |
81 |
24.0 bits |
11.7 Evs |
2293 ISO |