Sigma's third generation 12-24mm f/4 DG HSM Art Lens, available here with a Sigma SA mount, refines their ultra-wide arena and delivers an image with little distortion and with a high resolution for crisp photos with a modern full-frame digital image sensor. A member of Sigma's Art series, it boasts high image quality which is helped out by the use of FLD and aspherical elements, including an 80mm large-diameter molded glasses aspherical lens, that minimizes aberrations and distortion. Furthermore, it uses a Super Multi-Layer coating that minimizes flare and ghosting.,,Benefitting handling, the 12-24mm is equipped with a Hyper Sonic AF motor with an optimized algorithm for speed and accuracy. The lens also offers a large focusing ring with full-time manual override settings for quickly making adjustments. A rounded 9-blade diaphragm improves image quality by helping create smooth bokeh while the lens is constructed from a lightweight and durable thermally-stable composite. Also, the 12-24mm has a brass bayonet lens mount and is dust- and splash-proof. And, it is fully compatible with Sigma's USB Dock.,,,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.,This wide-angle 12-24mm f/4 zoom lens is designed for full-frame format Canon EF-mount cameras, and can also be used with APS-C models where it will provide a 19.2-38.4mm equivalent focal length.,Constant f/4 maximum aperture provides consistent performance throughout the zoom range.,F Low Dispersion and aspherical elements, including an 80mm large-diameter molded glass aspherical element, 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.,Minimum focus distance of 9.4" when shooting at 24mm for getting close to your subjects.,A rounded nine-blade diaphragm helps to produce an attractive out-of-focus quality.,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.,Dust- and splash-proof construction with rubber sealing to protect the mount and a water- and oil-repellent coating on the front and rear elements.,This lens is compatible with the optional Sigma USB Dock for fine-tuning different lens characteristics and updating its firmware.