It's such general assumptions that cause some people feel "obliged" to afford $$$$ for a specific lens with the hope to improve their photography (if not also to satisfy some other needs.)
I have run some tests of various lenses (Leica, Zeiss, Leica-R, CV, Canon, Nikon, etc.) on a Nex-5N, pixel density corresponding to 36MP on FF; also some tests of Leica-R lenses with Leitax adapters on my D800E against the 1.8G series lenses. Resolution tests were performed at enlargements of about 1.80m in horizontal length for all.
To give you an idea about "super sharpness" compare the MTF value of the Apo-Summicron 50/2 vs Macro-Elmarit-R 60/2.8 at their sharpest aperture of f5.6
at the central portion from the curves published by Leica AG. See any difference? None?
Now if you want to see how a Nokton 50/1.5 stands against the "super sharp" Macro-Elmarit-R 60/2.8, both at f5.6; check the below crops, all again about 1.80m on horizontal edge.
Short:
1. Generally the visual resolution differences may not be that "striking" as the hype the manufacturers try to create.
2. If you are after "super sharpness" then rather pay attention to FF-sensors with "super" pixel quantities. Such sensors may stun you with their resolution powers even with lowly 50mm lenses costing around $200. (Try to see a D800E shot with 50/1.8G for example.)
3. The recent trend is to "handle" distortion, CA or other optical deficiencies through in-camera or PP softwares. Old methods of "taking care" of such things on the drawing board is going to phase out. Smart techniques are being developed each year, to offer first-class optics with plausible costs. Many such lenses today provide
zero distortion and
zero CA either OOC or after PP.
