Sony A7 IV has a
33.0MP Full frame (35.8 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz XR processor. On the other hand, Nikon D800 has a
36.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor and features Expeed 3 processor.
Another difference between these two cameras is that Sony A7 IV's sensor lacks 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 A7 IV and D800 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A7 IV and Nikon D800 Cameras
Sony A7 IV and Nikon D800 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 Sony A7 IV and Nikon D800 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, A7 IV has scored 97, 2 points higher than D800.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A7 IV
97
25.4 bits
14.7 Evs
3379 ISO
Nikon D800
95
25.3 bits
14.4 Evs
2853 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 A7 IV
or the
Nikon D800 ,
including hyperfocal distance.