This lens is the first lens produced as part of Sigma's Sports line, making it ideally-suited for capturing fast-moving action with high precision. Its telephoto-length zoom range and fast maximum aperture make it especially useful for sports photography as well as wildlife, birding, and other fast-paced applications. Also benefitting these shooting scenarios is a wide range of customizable functions availed through the use of the Sigma USB Dock.Well-suited to outdoor photography, a dust- and splash-proof construction enables use of this lens in adverse conditions. Joint parts, such as the mount, focus and zoom rings, and switches, are sealed to provide this resistance and improve overall durability. Parts of the lens have also been optimally designed for more comfortable use, including textured rings and well-placed switches for more efficient operation. A brass bayonet mount is also used to increase the durability at this connection point, giving more strength and rigidity between the camera and lens system.The lens construction integrates two FLD (F Low Dispersion) glass elements and one SLD (Super Low Dispersion) glass element to help reduce color aberrations and sagittal coma flare to improve overall image quality. Lens elements also feature a Super Multi-Layer Coating to reduce flare and ghosting, which helps to improve image contrast and color fidelity throughout the zoom range.This lens is compatible with the Sigma USB Dock for fine-tuning and personalizing certain functions of the lens to fit your personal shooting style. A focus limiter can be set to constrain your lens' focusing distances to suit the distances at which you are shooting. Additionally, this lens features an inner focusing and zooming configuration so the physical length of your lens does not change during use; which greatly benefits the use of certain filters such as a polarizer.The USB Dock also allows you to customize the speed at which the autofocus system performs, how active the Optical Stabilizer system is during shooting, and allows you to easily update the lens' firmware