Sony RX1 has a
24.0MP Full frame (35.8 x 23.8 mm ) sized CMOS sensor . On the other hand, Pentax 645D has a
40.0MP Medium format (44 x 33 mm ) sized CCD sensor and features Prime II processor.
Pentax 645D's sensor provides 16MP more than Sony RX1'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.
One other difference between these two cameras that is worth mentioning is that Pentax 645D's sensor doesn't have an 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 RX1 and 645D sensor size comparison.
As seen above, Pentax 645D has a 1.7x Larger sensor area than Sony RX1. 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 Sony RX1 and Pentax 645D 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, RX1 has scored 93, 11 points higher than 645D.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Sony RX1 |
93 |
25.1 bits |
14.3 Evs |
2534 ISO |
Pentax 645D |
82 |
24.6 bits |
12.6 Evs |
1262 ISO |