Sharpness at 70mm

For this test, the Samyang AF 24-70mm F2.8 FE lens was attached to a Sony Alpha A9 body, which was in turn mounted to a sturdy tripod. Exposure delay mode was activated. Tonal and colour variance across the crops are due to change in natural light during the session.

The full frame at 70mm

The centre is soft wide open at f/2.8, with peak performance achieved in the f/5.6-f/11 range. Diffraction sets in at f/16.

The edges are not as sharp as the centre, with f/8 to f/11 the optimum settings.

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