A numerical value indicating the dispersion of optical glass, using the Greek symbol v. Also called the optical constant. The Abbe number is determined by the following formula using the index of refraction for three Fraunhofer s lines: F (blue), d (yellow) and c (red). Abbe number = sqrt(d) = nd ∙ 1/nF − nc An optical glass characteristic distribution chart is a graph using the Abbe number as the horizontal axis and the d line index of refraction as the vertical axis.

canonglossaryeuNULL

Foto-Magazin

NULL

F/64

denotes the degree of refraction of light of different wavelengths to different extents, given by a transparent material, such as glass. The lower the Abbe number, the greater the dispersion of colors.

profotoseducationglossary