Looks like the new Sony FE 24-70mm F2.8 GM is competitive with similar Nikon and Canon zooms, by DXO’s measure, but DXO hasn’t compared them with comparable sensors yet so sharpness isn’t overly relevant in their test, because of the substantially differing pixel count.
“In this comparison we’ve tested the Sony against the equivalent Canon and Nikon rival models. We’ve chosen the higher resolution 50-Mpix Canon EOS 5DS R to highlight the potential of the Canon combination, but even when tested on the lower 22-Mpix resolution Canon EOS 5D Mark III, the EF 24-70mm F2.8L II still achieves peak sharpness levels similar to the Sony. Still, it will be interesting to see just how the lens performs with the newer sensor in the A7R II.”
It is also interesting that the Sony performs best at 50mm, while the Canon is best at 24mm, and the Nikkor is best at 35mm. Many photographers prefer 50mm or 35mm, but I do not know many that shoot 24mm regularly. I’m curious to see if the Sony FE 24-70mm F2.8 GM will continue to shine on sensors like the 42MP a7R II and beyond.
“Given the emphasis on the high-grade components and construction to match the maker’s high-resolution sensors, we had high hopes for the Sony FE 24-70mm F2.8 GM, and we weren’t disappointed. It is the best-performing zoom in the maker’s range and can easily hold its own against the new AF-S Nikkor 24-70mm F2.8E ED VR. However, for edge-to-edge to sharpness, the Sony isn’t quite in the same league as the Canon EF 24-70mm F2.8L USM II, but we still have to add the Sony A7RII to propose a fair comparison with the 50 Mpix Canon EOS 5DSR. Nevertheless, the Sony does have certain strengths — better transmission and lower lateral chromatic aberration than many high-grade primes — and while certainly pricey, it’s still a competitive and tempting addition to the range.”