An overall DxOMark score of 100 points is the same as the Nikon D850. This makes it the highest-scoring mirrorless system camera to date, beating the A7R II by two points.
On the other hand this is the fourth-highest score ever recorded in DxO database. Sony A7R III score beaten only by the sensors in the medium-format Hasselblad X1D-50C and Pentax 645Z, and by the 12Mp full-frame Sony A7S II.
According to test results, the most significant improvement of the A7R III’s sensor over the A7R II’s is its dynamic range. The A7R III’s low-light ISO (Sports) score of 3523 is excellent. It’s actually only 0.4 EV higher than that achieved by the Nikon D850.
Sony A7R III Sensor Review : Ranks the same as D850 with 100 points
Sony A7r III sensor review compared to other related cameras:
From DxOMark conclusion:
It’s clear that the Sony A7R III has a high-performing sensor that’s capable of capturing images with a broad range of color and tone, while keeping noise well under control.
However, comparing the A7R III sensor to the Nikon D850’s reveals the advantage that the Nikon camera’s lower minimum sensitivity (ISO) value brings. Photographers who predominantly shoot in bright light or capture motionless subjects with the camera on a tripod will record the most information, be it color, tone, or detail with the Nikon D850 set to ISO 32. However, if they require values above that, the Sony A7R III sensor produces marginally better images.
Sony’s in-body 5-axis image stabilization system is widely respected, and if it achieves the 5.5 EV shutter speed compensation in the A7R III that the company claims, it would enable the camera to capture images at ISO 100 instead of at ISO 3200 (provided the subject is stationary).
Read more Sony Mirrorless talk / news.