Sharpness at 28mm

For this test, the Canon RF 28mm F2.8 STM lens was attached to a Canon EOS R8 body, which was in turn mounted to a sturdy tripod. Exposure delay mode was activated. Tonal and colour variance across the crops are due to change in natural light during the session.

The full frame at 28mm

Centre sharpness is outstanding from wide-open at f/2.8 all the way through to f/11, with f/16 being slightly affected by diffraction, and f/22 even more so.

The edges aren't as sharp as the centre, with the best results obtained from f/4 through to f/11.

Aperture	Centre Crop	Edge Crop
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22