The Nikon F-mount 18-400mm f/3.5-6.3 Di II VC HLD from Tamron is a true all-in-one lens to suit photographing the widest of vistas to the details of wildlife. In regard to the optics, a series of aspherical and low dispersion elements help to correct various aberrations and distortion for consistent sharpness and clarity throughout the zoom range. Additionally, supporting this 18-400mm all-in-one designation, a moisture-resistant construction ensures its use in trying environmental conditions. Two molded glass aspherical elements and one hybrid aspherical element help to reduce chromatic aberrations and distortion throughout the zoom range to deliver notable sharpness and accurate rendering.HLD (High/Low torque modulated Drive) motor delivers fast, precise, and responsive focusing performance that benefits both stills and video applications. The motor's design and circular arc shape also contribute to the lens's compact overall form factor. An electromagnetic diaphragm is used for more precise and consistent exposure control, especially when shooting at high continuous shooting rates. Both the zoom and focus rings are textured for improved grip and, additionally, a Zoom Lock mechanism prevents the zoom from accidentally extending when not in use.