Sharpness at 50mm

For this test, the Tamron 28-200mm F2.8-5.6 Di III RXD lens was attached to a Sony A7 III 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 50mm

Centre sharpness remains high through from f/3.5-f/11, with f/16-f/20 being adversely affected by diffraction. The edges aren't quite as sharp as the centre, with f/5.6-f/11 producing the sharpest results.

Aperture	Centre Crop	Edge Crop
f/3.5
f/4
f/5.6
f/8
f/11
f/16
f/20