Difference of lens dispersion

The biggest problem with chromatic dispersion on lenses is that it affects your wearing comfort. Dispersion is called Abbe number. The higher the Abbe number, the smaller the dispersion, and the two are inversely proportional. The Abbe number of the human eye is 58.6, so the closer the Abbe number of the lens is to this value, the more comfortable the lens will be. At present, only the Abbe number of a lens with a refractive index of 1.50 can approach this effect, which was first discovered by the German physicist Ernst Karl Abbe, who also used this effect.

Here are several graphs with different Abbe numbers.

The lower the Abbe number, the more obvious the rainbow phenomenon around things will be. From here, we can directly see the influence of Abbe number on vision, which is one of the reasons why lenses need a certain adaptation period. If you look out from the center of the lens, the dispersion will not be so obvious, and it will only appear in the peripheral field of vision of the lens when you look sideways. However, in practical application, the situation of turning eyes is far more than turning heads, so Abbe number is very important, which is also an important index of lenses. The lenses produced by regular manufacturers must indicate the Abbe number of the lenses on the packaging bag.

1.56 refractive index lens can hardly exceed Abbe number 40. Because of this problem, many high-end lens manufacturers, such as Rodenstein in Germany, directly eliminated the refractive index of 1.56.

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