Nikkor 400mm F/2.8D ED IF is a high-performance ultra telephoto prime lens designed for Nikon F mount cameras. The internal focusing lens employs the Silent Wave Motor to drive the focusing mechanism to deliver smooth, silent and semi-instantaneous autofocusing. Featuring lens construction of 11 elements in 9 groups, including 3 Extra-low Dispersion (ED) glass elements to reduce chromatic aberrations. Its 9-blade round diaphragm creates a natural blur for out-of-focus background. Offering approximately 12.47 feet close focusing distance during AF operation provides 1:8.3 magnification ratio. In addition, the lens has M/A mode for swift changes between manual and autofocus operation.