The Vivitar 75-205mm f/3.5-4.5 is short to medium telephoto manual focus lens. This version of Vivitar 75-205mm is designed for Nikon F mount cameras. The designated AI indicates Auto Indexing capabilities. This means the lens features AI ridge that meter couples when mounted to Nikon F cameras. The integrated prongs have cut-outs to help illuminate the f/stop markings for ADR. This multi-coated lens is ideal for travel, portraiture or candid photography.