Camera Labs posted the RAW quality comparision of the new Sony a7RII (Amazon | B&H | Adorama) and Canon EOS 5Ds R (Amazon | B&H | Adorama), using the same Sigma 50mm f/1.4 DG HSM Art lens set to f8 and the same 100 ISO and metered the same exposure. He processed the RAW files from both cameras in Adobe Camera RAW using identical settings: Sharpening at 70 / 0.5 / 36 / 10, Luminance and Colour Noise Reduction both set to zero, and the Process to 2012 with the Adobe Standard profile, and the same daylight white balance. Lens Profile Corrections were disabled.
From Camera Labs:
Looking closely, the slightly higher resolution of the 5DSr means the crops show a slightly smaller area, but I can’t see any additional detail in this particular example, nor indeed in any others I’ve made with other subjects. When both files are processed identically using ACR, the EOS 5DSr is a little more contrasty and the A7r II a little sharper, but both can be adjusted as desired.
The fact is the EOS 5DSr and Alpha A7r Mark II are capable of resolving very similar degrees of real-life detail and I wouldn’t choose one over the other in this regard. A handful of photographers who make huge tonal adjustments in RAW may prefer Canon for its uncompressed RAW files, and I certainly wish Sony would offer an uncompressed RAW option just to satisfy a complete market, but personally speaking I’ve never had any issues with retrieving reasonable highlight or shadow details from Sony files. Your mileage may vary, but again in this comparison, I’m satisfied the A7r Mark II and EOS 5DSr share essentially the same real-life resolving power.
Sony Alpha A7r Mark II sample movie: 4k UHD / 30p / 800 ISO / 100Mbit / 35mm / Standard style
Sony Alpha A7r Mark II sample movie: low light / 4k UHD / 30p / Super-35 OFF / 1600 ISO / 100Mbit / 70-200mm / Standard style