Both Sony A6400 and Sony RX1R have 24.0 MP resolution sensors but Sony A6400's sensor is APS-C (23.5 x 15.6 mm ) and Sony RX1R's sensor is Full frame (35.8 x 23.9 mm ).
Since Sony RX1R'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 Sony A6400.
One other difference between these two cameras that is worth mentioning is that Sony RX1R'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 A6400 and RX1R sensor size comparison.
As seen above, Sony RX1R has a 2.3x Larger sensor area than Sony A6400. 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. Sony A6400 and Sony RX1R sensors have been tested by DxO and the results show that RX1R has a better overall score of 91, 8 points higher compared to A6400's score of 83.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Sony A6400 |
83 |
24.0 bits |
13.6 Evs |
1431 ISO |
Sony RX1R |
91 |
25.0 bits |
13.6 Evs |
2537 ISO |