The photos were made with Canon EOS 6D camera, all handheld.
Lens was set on f/8.
Contrast, color and sharpness are very good except of extreme far corners, at least when the lens is used for landscape work focusing near infinity.
When I shoot with this lens at closer distances, softness of the far corners doesn't disturb. Photos of people or fashion even at f/2.8 are bit soft but acceptable.
I think I should close this lens to f/11 and pull back the focus towards the camera to get full frame sharpness when working at greater distances. You can read about it here.
Canon's 20 has just a little visible distortion.