Some general thoughts on the Canon 5DS R, backed up by my review of the Canon 5DS R so far. More field work coming of course, and I now have the Canon 5DS as well. The differences are subtle but visible: I strongly recommend the 5DS R model for most users.
FOR SALE: my Canon 5D Mark III in original box, etc with Really Right Stuff L bracket $2100 available early July.
vs Nikon D810
The Canon 5DS R is no match for the dynamic range of the Nikon D810. It can record more detail (17% more resolving power), but dynamic range and color quality are not to be set aside (these areas perhaps even more important when resolutions are similar).
Nikon is not likely to sit idly by, and can at the least be expected to get to 42 megapixels using the sensor in the Sony A7R II. If Nikon follows the 42MP path, it likely means high quality 4K video—which the 5DS R does not have. So a decision should take into account likely developments over the next 6-9 months since cameras are accessories (lenses are the primary). I would not be a “switcher” right now—give things a little time. But if you already have Canon, the 5DS R is a no-brainer.
I’ll be buying the Canon 5DS R shortly (just a matter of paying for the loaner); it’s a great camera in many ways and I look forward to using in the field over over the 5D Mark III: why should I waste my time shooting 24 megapixels when I can shoot 50MP with no more effort? For starters, focusing precisely in Live View is massively better on the 5DS R due to its 16X zoom and crisp details. But I love detail so great that later post-shot I can see details that the naked eye missed!
Sharpness and noise overall image quality
The Canon 5DS R delivers more than double the megapixels of its 22-megapixel predecessor, the Canon 5D Mark III. It does so without giving anything up—it’s an unequivocal win. Even if the final desired output is a lower file size, it’s a winner, because various good things happen via downsampling.
I’ve looked at the monochrome results with the Canon 5DS R, and I’d say unless you have money to discard or an ego problem and/or must employ M lenses (that’s a reasonable justification), the 5DS R blows away the Leica M Monochrom Typ 246 as a monochrome camera at less than half the price, with equal if not superior pixel resolution and tremendous flexibility and power of mapping tones when converting to monochrome (not to mention it can shoot color and autofocus and so on).