ED (Extra-low Dispersion) glass lenses effectively compensate for color fringing especially at high magnification, effective remove chromatic aberration. When observing white subjects such as swans or white eagles with an ordinary lens, a chromatic aberration is prominent at the border of the background and white part of the bird.
Nikon developed this optical glass for correction of chromatic aberrations. If the lens features both Nano and ED, the ED designation moves down to a part of the descriptor text—that’s the line below the Nikon name and the indicator window.
ED lens are high-quality Nikkor glass that come with built-in feature to correct image and color distortion that occurs when light rays of varying wavelengths pass through optical glass and don’t converge same focus point. Those lens deliver superior sharpness and contrast, even at maximum aperture.