Lens Lab
    Sigma DG 20-40 mm f/ 2.8 EX Aspherical
    Sigma DG 20-40 mm f/ 2.8 EX Aspherical

    Sigma DG 20-40 mm f/ 2.8 EX Aspherical

    20–40mm · f/2.8

    Overview

    The Sigma 20-40mm f/2.8 EX Aspherical offers good sharpness, especially at 20mm wide open, with minor corner softness at 40mm that clears by f/4. Distortion is present at 20mm but diminishes by 24mm. Build quality is solid, with smooth focus and zoom rings, though the 82mm filter thread is large and may cast shadows with built-in flash. It suits professionals seeking a budget f/2.8 zoom and enthusiasts wanting a fast constant aperture, but the price and filter size may deter some.