On Sun, 21 Jun 2020 15:23:09 -0400, me wrote:

On Fri, 19 Jun 2020 13:13:19 +0200, Paul Carmichael
wrote:

The Sigma 120-400mm 5.6 is the only tele/autofocus that I have. My other lenses are mostly
Samyang primes.

FYI, Review of the lens at imaging-resource.com
https://www.imaging-resource.com/len...sm-apo/review/

Sharpness
The 120-400mm is a fairly sharp lens, but its performance is optimized
for the wider range of its focal length spectrum. As you zoom in
towards the 400mm range, image sharpness degrades significantly.

and

Between 300 and 400mm, performance when used wide open (ƒ/5.6) is
nothing to write home about - very uneven and soft (3-5 blur units at
300mm, and 5-8 units at 400mm). Stopping down to ƒ/8 or ƒ/11 is
necessary to get any kind of sharpness out of the lens at this focal
length. Interestingly, image sharpness is better at ƒ/22-29 than when
used wide open at these focal lengths.