The first ED lens

Although the fluorite lens developed by Canon is famous for a while, the early calcium fluoride lens will make the refractive index of the lens deviate and affect the focus, and it is expensive, which is beyond the reach of ordinary amateur photographers. Nikon, also a top photographer in Japan, successfully trial-produced a synthetic ed lens named "Ultra-low Dispersion" at 1972, which not only has excellent sharpness performance, but also has anti-chromatic performance not inferior to Canon UD series. Nikon can't wait to apply this product to the Nikkor 300mm f/2.8 ED telescope released in the same year.

Because Nikon's ED lens anti-dispersion technology is cheap and reliable, it is widely used in astronomical telescopes and telescope heads. In addition, Nikon adopted an open marketing strategy to sell ed lenses to other manufacturers who could not produce anti-dispersion lenses, which gradually opened the popularity of ED and its effect was widely accepted by the public.