20mm (3) Minolta, CZ and Sigma at f/8.0 or f/11.0

At f/8.0, the three lenses are still noticeably different. I would say that the prime is best and the Sigma zoom needs to be stopped at f/11.0 to be similar. But what is wrong with f/11.0 for landscape pictures? ;)
The CZ zoom gives stellar performance, except in the extreme-extreme corner: on the corner crops, the top right is noticeably sharper than the bottom left.


Center performance at f/8.0, CZ 16-35, Minolta 20, Sigma 12-24:

and as a bonus, the Sigma at f/11.0:

Corner performance at f/8.0, CZ 16-35, Minolta 20, Sigma 12-24:

and again as a bonus, the Sigma at f/11.0:

Conclusion: the CZ is sharp at the center wide open, perfect for snapshots, street photography, etc... (where corner performance is relatively unimportant). The Minolta prime can be used for landscapes at f/5.6. The Sigma needs to be stopped at f/11.0 for best corner performance.


Next, 24mm CZ and Sigma with an additional lens, the Minolta 24-105 f/3.5 - 4.5 D.