A mid-tele zoom lens delivers prime lens-level image quality with a large F1.8 aperture throughout the zoom range.The SIGMA 50-100mm F1.8 DC HSM | Art lens covers the focal lengths of three prime lenses in one package: 85mm F1.8, 105mm F1.8, and 135 mm F1.8 (35mm equivalent). A true game-changer, this lens is perfect for portraits with subtle bokeh effects and more, and it sets a new standard for zoom lens image quality. FLD glass, SLD glass, and high-refractive index, high-dispersion glass help minimise aberrationsTo help minimise axial and transverse chromatic aberration, this lens features an optimal arrangement of three FLD ("F" Low Dispersion) glass elements, one SLD (Special Low Dispersion) glass element, three high-refractive index SLD glass elements, and one high-refractive index, high-dispersion glass element. By including one or more low-dispersion element in every element group, this lens ensures outstanding image quality throughout the zoom and focal range. From the start of the design process, SIGMA measured flare and ghosting to establish an optical design that is resistant to strong incidental light sources such as backlight. Featuring a newly designed Hyper Sonic Motor To achieve outstanding image quality and F1.8 brightness, SIGMA has enhanced its Hyper Sonic Motor (HSM). Optimising the layout as well as the shapes of the individual parts, SIGMA has made the HSM 30 percent slimmer than before. In turn, this slimmer HSM has made possible the combination of F1.8 brightness and high image quality in a zoom lens. Diaphragm unit designed for smooth operation The diameter of the diaphragm is the second-largest in the SIGMA lens line-up after that of the SIGMA 200-500mm F2.8 / 400-1000mm F5.6 EX DG, necessitating smoother and quicker operation than ever before. To achieve this goal, the diaphragm blades feature Carbon Feather film, and the diaphragm unit features a new polycarbonate made with fluorine. Thanks to these innovations, diaphragm operation is exceptionally smooth even during continuous shooting, while the new polycarbonate is exceptionally durable and wear-resistant. The 9-blade rounded diaphragm creates an attractive blur in the out-of-focus areas of the image. Inner focus and inner zoom Since its release, the SIGMA 18-35mm F1.8 DC HSM | Art has been widely used for videography. Understanding that the SIGMA 18-35mm F1.8 DC HSM | Art and new SIGMA 50-100mm F1.8 DC HSM | Art will often be used together, SIGMA has made the style of operation the same for both lenses, including the feel of focusing and zooming. Thanks to SIGMA's inner focus and inner zoom technologies, adjusting the focus and zoom rings does not change the length of the lens, and turning the zoom ring is not prone to cause focus shift. Other features The brass mount combines high precision with rugged construction. Its treated surfaces and enhanced strength contribute to the exceptional durability of the lens. The tripod socket is compact, making operation more stable and comfortable during handheld photography. Parts with electro-less nickel plating help ensure the quality and durability of the 90-degree click stops and smooth switching between the horizontal and vertical position. The shape of the socket also enhances ease of handling and carrying when the lens is not attached to a camera. New SIGMA GLOBAL VISION product lines are setting new benchmarks for image quality To ensure precise operation, internal parts feature generous use of metal and Thermally Stable Composite (TSC), which is highly compatible with metal parts. The lens barrel is engraved with the year of release for instant access to this information. TSC offers thermal expansion characteristics similar to those of aluminium. Parts made with TSC deform less, making lens construction of extremely high precision possible. Made in Japan With only a few minor exceptions, all of SIGMA's manufacturing, including moulds and parts, takes place under a single integrated production system in Japan. SIGMA is now one of the very few manufacturers whose products are truly made in Japan. SIGMA has developed their own proprietary MTF measuring system (A1)* using 46-megapixel Foveon direct image sensors. Even previously undetectable high-frequency details are now within the scope of their quality control inspections. All SIGMA 50-100mm F1.8 DC HSM | Art lenses are checked using this A1 system before they are shipped. SIGMA USB DOCK for SIGMA GLOBAL VISION lenses (optional) The SIGMA 50-100mm F1.8 DC HSM | Art is compatible with the optional SIGMA USB DOCK, allowing you to update your lens firmware and adjust the focus position and other settings. Simply connect the lens to the SIGMA USB DOCK and the dock to a computer to use the dedicated SIGMA Optimization Pro software and perform various types of customisation and adjustment.