Both Nikon D800 and Nikon D810 have 36.0 MP resolution sensors but Nikon D800's sensor is Full frame (35.9 x 24 mm ) and Nikon D810's sensor is Full frame (35.9 x 24 mm ).
Since Nikon D810'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 Nikon D800.
One other difference between these two cameras that is worth mentioning is that Nikon D810'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 D800 and D810 sensor size comparison.
Nikon D800 and Nikon D810 have the same sensor sizes so they will provide same level of control over the depth of field when used with 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. Nikon D800 and Nikon D810 sensors have been tested by DxO and the results show that D810 has a better overall score of 97, 2 points higher compared to D800's score of 95.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D800 |
95 |
25.3 bits |
14.4 Evs |
2853 ISO |
Nikon D810 |
97 |
25.7 bits |
14.8 Evs |
2853 ISO |