Sharpness at 40mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The LUMIX G VARIO 7-40mm F2.8 ASPH lens was attached to a Panasonic Lumix DMC-GX7 compact system camera, which in turn was mounted on a sturdy tripod. The self-timer was used to avoid any vibrations from pressing the shutter release. Slight tonal changes are due to slight changes in natural light during the session.

The full frame at 40mm

The centre is a little soft wide open, with peak performance achieved in the f/8-f/11 range. Diffraction sets in at around f/16 with its effects becoming much more visible at f/22.

The edges are somewhat soft at f/5.4, but sharpen up very nicely at f/8, which is the optimum setting.

Aperture	Centre Crop	Edge Crop
f/5.4
f/8
f/11
f/16
f/22