Nikon D5 has a
21.0MP Full frame (35.8 x 23.9 mm ) sized CMOS sensor and features Expeed 5 processor. On the other hand, Sony A7S III has a
12.0MP Full frame (35.6 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz XR processor.
Nikon D5's sensor provides 9MP more than Sony A7S III'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.
Below you can see the D5 and A7S III sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D5 and Sony A7S III Cameras
Nikon D5 and Sony A7S III 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
Both Nikon D5 and Sony A7S III sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, D5 has scored 88, 3 points higher than A7S III.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Nikon D5
88
25.1 bits
12.3 Evs
2434 ISO
Sony A7S III
85
24.2 bits
13.4 Evs
3900 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
Nikon D5
or the
Sony A7S III ,
including hyperfocal distance.