Sharpness at 20mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The Tamron 20mm F/2.8 Di III OSD M1:2 lens was attached to a Sony Alpha A7 III 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 20mm

Center sharpness is excellent wide-open at f/2.8 and outstanding between f/4 and f/11. At f/16 sharpness is beginning to drop off slightly to diffraction.

Edge sharpness is not quite so good as at the centre, with peak performance between f/5.6-f/11.

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