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.
CRC (Close Range Correction) System
The Close-Range Correction (CRC) system is one of Nikon's most important focusing innovations, for it provides superior picture quality at close focusing distances and increases the focusing range. With CRC, the lens elements are configured in a "floating element" design wherein each lens group moves independently to achieve focusing. This ensures superior lens performance even when shooting at close distances. The CRC system is used in fisheye, wide-angle, micro and selected medium telephoto NIKKOR lenses.