Nikon AF-S FX NIKKOR 400mm f/2.8E FL ED Vibration Reduction Fixed Zoom Lens with Auto Focus for Nikon DSLR Cameras Fast f/2.8 maximum aperture is well-suited to working in difficult lighting conditions Silent Wave Motor autofocus mechanism provides quick, quiet and precise autofocus performance Full-time manual focus override allows instant switching between AF and MF focusing systems by just rotating the focus ring at any time