Nikon AF Nikkor 18mm f/2.8D

The AF Nikkor 18mm f/2.8D was introduced as a native AF-D spec ultra-wide-angle lens. Until up to eventual debut of the AF-S Nikkor 14mm f/2.8D ED in 2003; this AF Nikkor 18mm lens has remained as the only option of a fixed focal length ultra-wide beyond the 20mm focal length. The 10 years of wait probably may provide some justification as Nikon seemingly had poured some real effort by designing this lens from ground up. As compare to the old classic manual focus 18mm, Nikon has improved it in a few areas. Firstly, the AF-D ultra-wide lens has been boosted with a faster maximum lens speed of f/2.8 from f/3.5. Internally, it uses an all new optical design in a rather complex 13 lens elements in 10 groups optical train. To counter any possible common aberrations commonly found in ultra-wide-angle lens design, an aspherical lens element has been added, which serves in suppressing coma and spherical aberrations and partly contributes to its overall high image definition. The lens can focus down to a minimum distance of 0.25m (0.85 ft) and delivers a magnification ratio of approx. 1/9.1 - it was slightly weaker than the MF counterpart in this area. Further, Nikon also incorporated the lens with a Close Range Optical Correction System so as to auto compensate via its rear optical groups to retain its excellent optical quality when shooting in close distances.