Sharpness at 135mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The Canon EF 70-200mm F2.8L IS III USM lens was attached to a Canon EOS 5DS R body, which in turn was mounted on a sturdy tripod. Self-timer mode was activated. Slight tonal changes are due to slight changes in natural light during the session.

The full frame at 135mm

Both center and edge sharpness are outstanding between f/2.8 and f/11. At f/16 sharpness is beginning to drop off due to diffraction, becoming much more prominent at f/22 and f/32.

Aperture	Centre Crop	Edge Crop
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22
f/32