Also, why not just pick up the RF 16mm F2.8 STM and the RF 28mm F2.8 prime lenses instead? These are Canon's smallest lenses for full-frame cameras and the pair combined costs half the price of ...
Central sharpness is outstanding from f/2.8 to f/5.6, excellent from f/8 to f/16 and still very good at f/22. The edges do not fare so well, but are very good from f/2.8 to f/5.6, good from f/8 to ...