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. Prime wide-angle 20mm f/1.4 lens is designed for FX format Nikon F mount DSLRs, and can also be used with DX models where it will provide a 30mm equivalent focal length. Fast 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. Two FLD, five SLD, and two aspherical elements have been incorporated within the lens design to correct for chromatic aberrations throughout the entire focusing range and help to ensure high image sharpness, clarity, and contrast regardless of focus point or aperture setting. This optical design also helps to control distortion and limit vignetting. 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. A rounded nine-blade diaphragm helps to produce an attractive out-of-focus quality. Fixed petal-shaped lens hood helps to reduce lens flare when working in strong lighting conditions and also offers some protection to the front element of the lens. The lens is constructed using a Thermally Stable Composite (TSC) material, along with traditional metals, for greater precision and use in wide temperature variations. The bayonet mount is constructed from brass for ensured accuracy and durability. This lens is compatible with the optional Sigma USB Dock for fine-tuning different lens characteristics and updating its firmware.