Canon 40D has a
10.0MP APS-C (22.2 x 14.8 mm ) sized CMOS sensor . On the other hand, Nikon D850 has a
46.0MP Full frame (35.9 x 23.9 mm ) sized BSI-CMOS sensor and features Expeed 5 processor.
Nikon D850's sensor provides 36MP more than Canon 40D'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 Nikon D850'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 40D and D850 sensor size comparison.
As seen above, Nikon D850 has a 2.6x Larger sensor area than Canon 40D. 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. Canon 40D and Nikon D850 sensors have been tested by DxO and the results show that D850 has a better overall score of 100, 36 points higher compared to 40D's score of 64.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Canon 40D |
64 |
22.1 bits |
11.3 Evs |
703 ISO |
Nikon D850 |
100 |
26.4 bits |
14.8 Evs |
2660 ISO |