Sharpness at 18mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The Canon EF-S 18-135mm f/3.5-5.6 IS USM lens was attached to a Canon EOS 80D 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 18mm

Centre sharpness remains high through from f/5.6 to f/11, with f/16 and f/22 being adversely affected by diffraction. The edges are almost as sharp as the centre, with f/5.6 to f/11 again producing the sharpest results.

Aperture	Centre Crop	Edge Crop
f/3.5
f/5.6
f/8
f/11
f/16
f/22