Sigma 20mm F1.4 DG DN | Art (L-Mount)

Reviewers call it a well-featured, well-priced f/1.4 ultra-wide whose best results come a stop down. Wide open it shows some overall softness, even in the centre; f/2 is clearly sharper and f/2.8 is close to its best, though corners never become outstanding and Sony's 20mm f/1.8 G is a little crisper. Coma is well controlled and the field is flat at infinity, which suits astro work, and vignetting and distortion are well handled once profiles are applied.

Autofocus is fast, accurate and nearly silent, with an occasional faint buzz and little focus breathing. Testers like the focus-ring lock, the de-clickable aperture ring and the thorough sealing, and find bokeh pleasant for an ultra-wide. The criticisms are size and weight against f/1.8 rivals, the length with the hood fitted, and the need for specific sheet filters at the rear.