Sigma 20-60mm F2.8-4 DG | Contemporary (L-Mount)

Reviewers found it sharp in the centre throughout the zoom range even wide open, and unusually good to the corners at 20mm; edges are a little softer at mid and long focal lengths at wide apertures, and the lens is sharp corner to corner around f/8 to f/11. Colour fringing is minimal and removed by in-camera correction. Autofocus is quick, quiet and accurate, focus breathing is low, and close-up results are sharp.

The main caveat is reliance on software: uncorrected files show strong, complex barrel distortion at 20mm, pincushion at 60mm and fairly strong vignetting wide open, all corrected by camera or raw profiles. Reviewers also note the inner barrel extension, plastic build and the lack of an aperture ring or AF/MF switch, but call it a fine-value lightweight alternative to 24-70mm zooms.