What does this mean

[Imacer]

Anomalous Dispersion

[TCav]

Imacer wrote:

Anomalous Dispersion

anomalous 1 : inconsistent with or deviating from what is usual, normal or expected : IRREGULAR, UNUSUAL 2: of uncertain nature or classification

dispersion4 : the seperation of light into colors by refraction or diffraction with formation of a spectrum; also : the seperation of nonhomogeneous radiation into components in accordance with some characteristic (as energy)

anomalous dispersion 1 : an unusual dispersion of light into colors; or : a dispersion of light into unusual colors2 : a physical impossibility 3 : a meaningless assemblage of words intended to impress and confuse the casual reader. See political writingorcosmetics advertisements.

[[email protected]]

Could you give the context in which the term was used? It could be just poor translation of the term "chromatic aberration".

[Norm in Fujino]

It's a way of helping to correct Chromatic Aberration; from Tamron's website:

"
[align=left]About AD (Anomalous Dispersion) Lens Elements[/align] [align=justify]Anomalous Dispersion glass is a special optical glass that delivers an abnormally large partial dispersion ratio (amount of dispersion at a given wavelength range within visible light) relative to a specific wavelength zone. By combining AD glass elements with elements made of normal glass with different dispersion characteristics, dispersion factors of a specific wavelength can be controlled, resulting in effective compensation of on-axis chromatic aberration on telephoto lenses, or lateral chromatic aberration often associated with wideangle lenses of conventional optical configuration. (Model 190D)[/align] [align=justify]The difference in partial dispersion factors between normal optical glass and AD glass elements[/align][align=justify]
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