Sharpness at 12mm

For this test, the Samyang AF 12mm F2 X lens was attached to a Fujifilm X-S10 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 12mm

Centre sharpness is excellent wide-open at f/2 through to f/11, with f/16 and f/22 being adversely affected by diffraction.

The edges aren't quite as sharp as the centre, with f/4 to f/11 producing the sharpest results.

Aperture	Centre Crop	Edge Crop
f/2
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22