The Leica L-mount Sigma 40mm f/1.4 DG HSM Art Lens is a wide normal-length lens characterized by a bright design and sophisticated optical layout. The fast f/1.4 maximum aperture helps to achieve shallow depth of field and selective focus effects and also suits working in difficult lighting conditions. A Super Multi-Layer Coating is also featured and helps to minimize flare and ghosting for greater contrast and color accuracy when working in strong lighting conditions. The physical design features a brass bayonet mount, which offers rigidity and mounting precision along with a seal to guard against dust and moisture. Additionally, a rounded nine-blade diaphragm contributes to a pleasing bokeh quality. Short-normal prime is designed for full-frame Leica L-mount mirrorless cameras, however, is also suitable for APS-C models where it provides a 60mm equivalent focal length. Three F Low Dispersion (FLD) and three Special Low Dispersion (SLD) elements are featured in the optical design and help to reduce color fringing and chromatic aberrations for improved clarity and color accuracy. A Super Multi-Layer Coating has been applied to lens elements in order to minimize lens flare and ghosting and contribute to producing contrast-rich and color-neutral imagery, even in backlit conditions. The integrated HSM (Hyper Sonic Motor) realizes quick and quiet autofocusing, which is further complemented by an optimized AF algorithm to produce smoother focusing performance. The HSM also permits full-time manual focus control simply by rotating the focus ring at any time. The bayonet mount is constructed from brass for ensured accuracy and durability. Additionally, rubber sealing is incorporated in the mount design to render it dust- and splash-resistant.