I lucked out and it looks like I’ll be getting both the Canon 5DS and 5DS R, so among other things, I can compare the two (5DS has an anti-aliasing filter, 5DS R does not).
Which lenses for 50 megapixels?
These are the lenses that I recommend for the best odds of actually recording 50 megapixels of detail and/or the best chances of approaching the best possible in that focal length range (takes into account sharpness-damaging behaviors like focus shift and field curvature as well as absolute performance:
- Zeiss Otus 55mm f/1.4 APO-Distagon and Zeiss Otus 85mm f/1.4 APO-Planar and Zeiss 135mm f/2 APO-Sonnar.
- Sigma 24mm f/1.4 DG HSM Art, Sigma 35mm f/1.4 DG HSM Art, Sigma 50mm f/1.4 DG HSM Art.
- Canon 11-24mm f/4L IS and Zeiss 15mm f/2.8 Distagon.
- Canon 200m f/2L IS, Canon 300mm f/2.8L II, Sigma 120-30mm.
Even so, few of these lenses will be free of various weaknesses.