I'm certain you're aware that deep down all us Canon uses know we made a huge mistake; we're full of regret and disappointed with the performance of our cameras and ultimately disheartened by the photographs they produce. Nikon and Sony are much, much better cameras in every way and you guys really know your stuff... can we carry on with the reason for the thread now "5ds or 5dsr"?
Indeed.
Carl, I think it has a lot to do with the subject matter one shoots. Technically, a discrete image sensor
has to be bandwidth limited (by an AA-filter), it's Digital Signal Processing 101. The simple reason is that it will otherwise generate aliasing artifacts, such as stairstepping, coarser(!) or fake moiré detail, False color aliasing, and it is harder to sharpen without exaggerating the aforementioned artifacts. However, that will only happen if there is more/finer detail than the sensor can resolve. Having a high resolution sensor with dense sampling helps, as does getting the subject as large as possible in the frame, with little cropping.
That means that the subject matter has to be in the plane (a DOF zone) of optimal focus, otherwise defocus will kill the potentially troublesome subject detail. Also narrow apertures that cause diffraction blur will reduce the chance of fine detail getting through with enough modulation to cause aliasing issues. And obviously the lens must be reasonably good. So, one
may get away with the negative effects of the lacking AA-filter, but it's more risky because when it strikes, there is little to do about it (except time consuming postprocessing).
The 5DS does not totally eliminate the chance of Aliasing artifacts from damaging the subjects (surface) structure, because it is underdimensioned, but it does reduce common risks. Proper deconvolution Capture sharpening will restore a lot of the detail/contrast that looked like it had been lost. Sharpening 5DS R shots risk bringing out the aliasing, if there is any. So with more sharpening potential for the 5DS and less (or only targeted) for the 5DS R, the effective visual resolution differences will be small. There will be differences, but they will be small.
There is one additional factor that makes a difference, and that is the Raw converter. Capture One for instance does a very good job handling the aliasing artifacts that
both cameras can generate. It can't unscramble the mess that aliasing is, but it does not over-accentuate it either, while still extracting higher levels of detail than e.g. Lightroom does.
Cheers,
Bart