Sharpness at 100mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The Sigma 100-400mm F5-6.3 DG DN OS lens was attached to a Sony A7 III camera 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 100mm

Centre and edge sharpness are commendably good wide-open at f/5, and remain high through from f/5.6 to f/11, with f/16 and f/22 being adversely affected by diffraction.

Aperture	Centre Crop	Edge Crop
f/5
f/5.6
f/8
f/11
f/16
f/22