Sigma 693955 50-100mm f/1.8 DC HSM Art Lens for Nikon, Black 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. Spanning a range of short telephoto focal lengths, this 50-100mm Lens is designed for Nikon F-mount DX-format DSLRs, where it provides a 75-150mm equivalent focal length range. Impressively fast f/1.8 constant maximum aperture benefits working in difficult lighting conditions