I have recently purchase a 5Ds R I have a trusty 24Mp 5D MkIII and I was interested to see how the 50Mp full frame sensor would behave under various conditions
Squeezing that many pixels into a a full frame sensor was asking a lot and because of that the noise levels at moderate ISO's say1600 are quite high compared with the 5D which will go to very high levels with ease due to its larger pixel size.
So I have been experimenting with a base ISO of 100 to get the best results that means in low light a tripod, in good light Canon's 4 stop IS lenses suffice.
The level of detail available with this sensor is amazing providing the best Canon lenses are used, I use a 16-35mm f4 IS L lens, a 24-70mm 2.8 mkii L and a 100-400mm IS Mkii L lens which covers most of my needs.
File size in RAW at maximum is about 65Mp a huge file size which means a large capacity fast memory card and a very large capacity hard drive.
I am using a Apple iMac and uploading some images to iCloud to save on hard disc space.
Below are two pictures where I cropped the road sign from the centre of the large image file size in RAW was 65mb to gauge enlargement potential.
These images have been exported in small jpeg size for showing here. I chose the "fine detail" setting in the menu and no post edit sharpening was applied