This Canon EF-mount Sigma 50-100mm f/1.8 DC HSM is an Art-series zoom mixing impressive versatility with advanced optics. The bright f/1.8 constant maximum aperture offers consistent low-light performance throughout the zoom range and also affords greater control over focus placement for shallow depth of field and selective focus applications. The optical design incorporates a series of low dispersion and high-refractive index elements, which help to achieve high clarity and sharpness by suppressing various aberrations, color fringing, and distortion. A Super Multi-Layer Coating has been applied, too, which controls lens flare and ghosting for improved contrast and color accuracy. Balancing the optical merits, this 50-100mm also sports an advanced Hyper Sonic Motor, along with an internal focusing and zoom design, to promote fast, quiet, and precise autofocus performance. 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. Impressively fast f/1.8 constant maximum aperture benefits working in difficult lighting conditions throughout the zoom range and also offers increased control over focus when working with selective focus techniques. 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. Internal zoom and focus designs limit the overall length of the lens during operation for more intuitive, controlled handling as well as faster performance. Constructed using a Thermally Stable Composite (TSC) material for greater precision and use in wide temperature variations. Additionally, a brass bayonet affords improved mounting accuracy and rigidity. This lens is compatible with the optional Sigma USB Dock for fine-tuning different lens characteristics and updating its firmware.