ED APO FCD100 Triplet Series
Chromatic aberration is the phenomenon of different colors focusing at different distances from a lens. Telescope objective lenses for wide-band digital imaging in astronomy must have apochromatic correction, as the optical sensitivity of typical CCD imaging arrays can extend from the ultraviolet through the visible spectrum and into the near infrared wavelength range. Apochromatic designs require optical glasses with special dispersive properties to achieve three color crossings. Explore Scientific achieves this using costly ED (Extra-Low Dispersion) glass.