Sharpness at 40mm

For this test, the Sigma 40mm F1.4 DG HSM lens was attached to a Canon EOS 5DS R body, which in turn was mounted on a sturdy tripod. Exposure delay mode was activated. Tonal and colour variances across the crops are due to changes in natural light during the session.

The full frame at 40mm

Both centre and edge sharpness are excellent wide open at f/1.4, and outstanding through from f/2 to f/11, with f/16 being adversely affected by diffraction.

Aperture	Centre Crop	Edge Crop
f/1.4
f/2
f/2.8
f/4
f/5.6
f/8
f/11
f/16