DxOMark has published their Sony a7R III sensor review and test results: “The Sony A7R III achieves an overall DxOMark sensor score of 100 points, the same as the Nikon D850. This makes it the highest-scoring mirrorless system camera to date, beating the A7R II by two points.”
So, the Sony a7R III ties the Nikon D850 as the best full-frame camera they’ve ever tested with a score of 100. And it means the Sony a7R III is the best full-frame mirrorless camera DxOMark has ever tested, besting the former king, the Sony a7R II, which scored a 98.
The Nikon D850, Sony A7R III, and A7R II sensors occupy the third, fourth, and fifth slots in our scoring hierarchy. They are beaten only by the medium-format sensors in the Hasselblad X1D-50C (102 Points) and the Pentax 645Z (101 Points), which take the first and second slots, respectively.
Conclusion from DxOMark:
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).