Lens Lab
    Sigma 20mm F1.8 EX DG Aspherical RF
    Sigma 20mm F1.8 EX DG Aspherical RF

    Sigma 20mm F1.8 EX DG Aspherical RF

    20mm · f/1.8

    Overview

    The Sigma 20mm F1.8 EX DG Aspherical RF is a unique ultra-wide prime offering an f/1.8 aperture unmatched by competitors, ideal for low-light and astrophotography. However, wide-open image quality is very soft, effectively requiring stopping down to f/2.8 for decent sharpness. Build quality is solid with a sturdy barrel and included hood, though the crinkle finish scuffs easily. Autofocus is accurate in good light but noisy and prone to hunting in dim conditions. Strong vignetting and flare are additional drawbacks. Best suited for users who prioritize speed over ultimate sharpness.