Phase Fresnel (PF) lens elements effectively compensate for chromatic aberration and ghosting when combined with ordinary glass lens elements. The PF lens element is based upon the Phase Fresnel lens, which appears to have a series of concentric circles engraved onto it. Utilizing a Phase Fresnel lens element allows Nikon engineers to use fewer lens elements, resulting in a more compact and lightweight lens. Due to the characteristics of a PF (Phase Fresnel) lens that utilizes the photo diffraction phenomenon, when there is a strong light source within the frame or when light enters the lens from outside of the frame, ring-shaped coloured flare may occur according to shooting conditions. This phenomenon can be minimized with "PF Flare Control" to be included in Capture NX-D (ver.1.1.0 or later). For more information, see software Help/manual. Capture NX-D is available from the Nikon website. Be sure to keep your software up to date.