Chromatic Aberration

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Chromatic aberration is probably most easily understood as a prism effect. When light shines through a prism, you see that different colors of light bend (undergo Refraction) differently and create a rainbow effect. When light shines through any lens, including glasses and the natural lens of your eye, the same occurs to a lesser degree. The effect of this is that the Focal length of the lens is not exactly the same for all colors of light.

Chromatic aberration lens diagram

Duochrome test


The chromatic aberration expected during a normal eye exam is about a half diopter difference between red and green. This can be a handy test to dial in a final prescription by looking at text on red and green backgrounds and seeing which is clearer.

External Sources

Lens Material

Different materials have different Abbe numbers. Materials with higher values are better, since they tend to have less chromatic aberration.

Here are some typical values:[1]

Material Index Abbe Value
Crown Glass 1.523 59
High Index Glass 1.60 42
High Index Glass 1.70 39
Plastic CR-39 1.49 58
Mid Index Plastic 1.54 47
Mid Index Plastic 1.56 36
High Index Plastic 1.60 36
High Index Plastic 1.66 32
Trivex 1.53 43
Polycarbonate 1.58 30
MR-174 1.74 32