I just gotten my Canon 5Dsr for a week and has been trying it out with the Zeiss Makro Planar 50mm f;2.0 and find that the images are soft even at f-stop @ f;8.0. I have discussed with professional photographer that lenses other than the Otus series are in-comparable to the high 50.4mp resolution with the current non-Otus lenses.
The 5Dsr has a 16X live-view magnification and focus subject on the live-view screen appears to be soft. I yet to try this on my Zeiss 15mm, 21mm, 35mm f;2.0; hopefully I will test it in this coming weekend. I have processed captured images in Lightroom and it appear soft too.
As this Camera is still new in the market, I hope to get feed back from those who has it in regards to the non-optimisation of the lenses and the sensors pairing. Maybe Zeiss themselves can gives some comment on this issue.