Panasonic LUMIX S 20mm F2.5

Testers find the centre of the frame very sharp from f/2.5, but the edges and corners are soft wide open and only become fully convincing around f/8. Colour fringing is mostly well controlled, though one test saw corner fringing persist through the middle apertures. Distortion is strong in uncorrected raw files and is corrected automatically. Autofocus is quick, accurate and close to silent.

The main optical weakness reported is ghosting and flare against bright light, which matters more because no hood is supplied. Build quality impressed reviewers for the size, with a metal mount, a sealing gasket and a function button. The verdict is a well-built carry-everywhere wide for compact bodies, fairly priced rather than a bargain, and not the choice for critical edge-to-edge sharpness.