The Sigma 20mm f/1.4 DG HSM Art Lens for Leica L-Mount is a member of the "Art" series of Global Vision lenses from Sigma. The 20mm f/1.4 combines a sophisticated optical design with a durable physical design. This lens has 15 elements in 11 groups, including two "F" Low Dispersion (FLD) elements, five Special Low Dispersion (SLD) elements. Two aspherical elements are featured to significantly reduce spherical & chromatic aberrations, & to limit distortion for sharp, clean, & evenly illuminated images. A Super Multi-Layer Coating has been applied to minimize flaring, ghosting, & surface reflections, as well as to provide increased contrast & color accuracy. The lens' wide focal length & consistency of high quality images makes this lens especially suitable for landscape, architectural, interior, & astrophotography applications. The fast f/1.4 maximum aperture makes it ideal for natural & low-light shooting. Its Hyper Sonic Motor, which provides smooth, fast, & near-silent autofocus performance. The focusing motor also allows for full-time manual focus at any time by rotating the focus ring. The focus ring allows for refined manual control & focusing as close as 10.9". Its barrel is designed using a Thermally Stable Composite material, which assists with working in a variety of temperatures & conditions. The lens mount is designed from brass, making it a durable and long-term choice, while increasing the ease of mounting.