Sharpness at 40mm

For this test, the Panasonic Lumix S 20-60mm f/3.5-5.6 lens was attached to a Panasonic S1 IIE body, which was in turn mounted to a sturdy tripod. Exposure delay mode was activated and image stabilisation turned off. Tonal and colour variance across the crops are due to change in natural light during the session.

The full frame at 40mm

The centre is a little soft wide open at f/2.8, sharpening up at f/4, with peak performance achieved in the f/8-f/11 range. Diffraction starts to set in at f/16.

The edges are almost as sharp as the centre, with f/8 to f/11 again being the optimum settings.

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