Roger at LensRentals.com has completed his initial resolution tests on the brand new Canon EOS 5DS and EOS 5DS R camera bodies.
The cameras were tested with the Zeiss 21mm f2.8, EF 50mm f/1.4, Zeiss 85mm f/1.4 Otus and Canon EF 300mm f/2.8L IS II. As LensRentals.com found, the EOS 5DS and EOS 5DS R outresolve the Canon EOS 5D Mark III without much issue, although the differences do vary depending on the lens.
Summary from LensRentals.com:
Just as it was the Nikon high resolution cameras were released, it will take months of testing and photographer experience to determine which lenses do exactly what with the new cameras. But it's not a critical thing to know at first. Every lens will provide better on the new cameras, at least in the center of the image. How much of a difference will range from noticeably better, to “wow” depending upon the lens, type of photography, and subject matter.
There are many other things that are going to be as, or more, important to the photographer than absolute resolution. But absolute resolution is always a good thing. And these cameras certainly deliver phenomenal resolution. Read the full article