ps, I have dug out the measured sharpness of the Sigma 500/5.6 on websites that do IMATEST.
https://www.pcmag.com/reviews/sigma-500mm-f56-dg-dn-os-sports
On the 61 Mpx A7Riv, the Sigma at f/5.6 gives 3,900 lines, which is less than the Sony FE 200-600mm with 4,000 lines at 600mm f/6.3. The...