Sony A7R IV has a
61.0MP Full frame (35.8 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz X processor. On the other hand, Sony A7 III has a
24.0MP Full frame (35.8 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz X processor.
Sony A7R IV's sensor provides 37MP more than Sony A7 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.
Another difference between these two cameras is that Sony A7R 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 A7R IV and A7 III sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A7R IV and Sony A7 III Cameras
Sony A7R IV and Sony A7 III 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. On the other hand, since Sony A7 III has 150% larger pixel area (35.50µm 2 vs 14.15µm 2 ) compared to Sony A7R IV, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
DxOMark Sensor Scores
Both Sony A7R IV and Sony A7 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, A7R IV has scored 99, 3 points higher than A7 III.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A7R IV
99
26.0 bits
14.8 Evs
3344 ISO
Sony A7 III
96
25.0 bits
14.7 Evs
3730 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 A7R IV
or the
Sony A7 III ,
including hyperfocal distance.
