Both Canon 1Ds MIII and Nikon D7500 have 21.0 MP resolution sensors but Canon 1Ds MIII's sensor is Full frame (36 x 24 mm ) and Nikon D7500's sensor is APS-C (23.5 x 15.7 mm ).
Since Canon 1Ds MIII'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 D7500.
One other difference between these two cameras that is worth mentioning is that Nikon D7500'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 1Ds MIII and D7500 sensor size comparison.
As seen above, Canon 1Ds MIII has a 2.3x Larger sensor area than Nikon D7500. 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 1Ds MIII and Nikon D7500 sensors have been tested by DxO and the results show that D7500 has a better overall score of 86, 6 points higher compared to 1Ds MIII's score of 80.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Canon 1Ds MIII |
80 |
24.0 bits |
12.0 Evs |
1663 ISO |
Nikon D7500 |
86 |
24.3 bits |
14.0 Evs |
1483 ISO |