Sony A57 has a
16.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor . On the other hand, Nikon D500 has a
21.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor and features Expeed 5 processor.
Nikon D500's sensor provides 5MP more than Sony A57'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 D500'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 A57 and D500 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A57 and Nikon D500 Cameras
Sony A57 and Nikon D500 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the 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 A57 and Nikon D500 sensors have been tested by DxO and the results show that D500 has a better overall score of 84, 9 points higher compared to A57's score of 75.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A57
75
23.4 bits
13.0 Evs
785 ISO
Nikon D500
84
24.1 bits
14.0 Evs
1324 ISO
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sony A57
or the
Nikon D500 ,
including hyperfocal distance.
