AS stands for Aspherical lens elements. This type of lens utilizes non-spherical surfaces on either one or both sides of the glass in order to eliminate certain types of lens aberration.
ED (Extra-Low Dispersion) Glass
An optical glass developed by Nikon that is used with normal optical glass in telephoto lenses to obtain optimum correction of chromatic aberrations.
A NIKKOR lens in which only the internal lens group shifts during focusing. These lenses will be designated with the abbreviation IF on the lens barrel.