Truly wide and truly fast, the Canon EF mount 20mm f/1.4 DG HSM Lens is a member of the venerable Art series of Global Vision lenses from Sigma and pairs a sophisticated optical design with a robust physical construction. Comprised of 15 elements in 11 groups, the lens design includes two "F" Low Dispersion (FLD) elements, five Special Low Dispersion (SLD) elements, and two aspherical elements to significantly reduce chromatic and spherical aberrations, as well as limit distortion for clean, sharp, and evenly illuminated imagery. A Super Multi-Layer Coating has also been applied to minimize surface reflections, flare, and ghosting for increased contrast and color accuracy. The wide focal length and consistent image quality make this lens especially suitable for landscape, interior, architectural, and astrophotography applications, while the fast f/1.4 maximum aperture deems it ideal for natural and low-light shooting. Complementing the optical performance is an equally adept Hyper Sonic Motor, which provides fast, smooth, and near-silent autofocus performance. This focusing motor also enables full-time manual focus override at any time just by rotating the focus ring for refined manual control and focusing as close as 10.9". The lens barrel is constructed using a Thermally Stable Composite material, which supports working in a wide variety of temperatures and conditions, and the lens mount is constructed from brass for long-term durability and mounting accuracy. Additionally, this lens is also compatible with the optional Sigma USB Dock for fine-tuned control over focusing parameters and other lens characteristics. 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 full-frame format Canon EF mount DSLRs, and can also be used with APS-C models where it will provide a 32mm 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.
