Sharpness at 8mm

For this test, the Fujifilm XF 8mm F3.5 R WR lens was attached to a Fujifilm X-S20 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 8mm

The centre is pleasingly sharp even wide open at f/3.5, with peak performance achieved in the f/4-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/3.5
f/4
f/5.6
f/8
f/11
f/16
f/22