As part of the Art line within Sigma's Global Vision series, this lens is designed to achieve truly notable optical performance and is ideally suited for creative and artistic applications. Wide-angle prime is designed for full-frame Canon EF-mount cameras, however is also suitable for APS-C models where it provides a 56mm equivalent focal length. Impressively bright f/1.4 maximum aperture is well-suited for working in low-light conditions and also provides greater control over the focus position when using shallow depth of field techniques. One F Low Dispersion (FLD) element and four 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. Two aspherical elements are used to help limit distortion and spherical aberrations and also contributes to greater overall sharpness and accurate rendering. Floating elements system helps to realize consistent optical performance throughout the focusing range, from 11.8" to infinity. 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. Rounded nine-blade diaphragm contributes to a smooth and pleasing bokeh quality. 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. This lens is compatible with the optional Sigma USB Dock for fine-tuning different lens characteristics and updating its firmware.