Nikon uses ED (Extra-low Dispersion) and Super ED glass in their lenses. Here, we go into the technology behind this to find out why it's the ideal choice for optimum image quality.
ED and Super ED glass help correct chromatic aberrations and optical colour defects. These are caused when different wavelengths of light don't converge on the same point after passing through the glass of the lens.
In the past, calcium fluorite was used to get around the problem in telephoto lenses, but the substance was sensitive to temperature changes and because of this was prone to cracking easily.
To combat this Nikon came up with ED glass. It has all the pros, but none of the cons of calcium fluorite. ED glass helps to deliver amazing sharpness and contrast in images, even at maximum aperture.