DxOMark published their test results of the Canon 5DS and 5DS R cameras:
One of the more interesting comparison is agains the Nikon D810 and Sony a7R cameras:
Canon 5DS & 5DS R DxOMark's conclusion:
Boasting an unprecedented 50.6Mp resolution, the EOS 5DS and 5DS R offer a unique DSLR shooting solution. What’s more, our industry standard tests have shown these are the best sensor results yet for a Canon chip, with the 5DS cameras offering a small step up for image quality against other full-frame semi-pro models such as the EOS 6D and EOS 5D Mark III. Our measurements show that there’s very little difference between the 5DS and 5DS R sensors, but we’ve seen both models post better scores in print results compared to those on screen.As usual, the best scores are recorded at each sensor’s base ISO setting, and here the 5DS sensors are a little off the pace against the best chips we’ve analyzed (in the Nikon D810 and the Sony A7R). This is particularly true for Dynamic Range, where the Nikon and Sony models boast around a two-stop advantage at base ISO, although the gaps narrows as sensitivity is increased.
With its massive resolution and best results in print, the EOS 5DS and 5DS R are great solutions for photographers shooting at low ISO sensitivities for large scale prints.
