Which statement about chromatic aberration and Abbe value is true?

• A. The Abbe value has no effect on chromatic aberration.
• B. Higher Abbe value reduces chromatic aberration.
• C. Higher Abbe value increases chromatic aberration.
• D. Chromatic aberration is independent of Abbe value.

Answer: (B)

Chromatic aberration happens because different wavelengths refract by different amounts as light passes through a lens. The Abbe number of a glass captures how much its refractive index changes with wavelength: a higher Abbe value means less dispersion across the spectrum. With less dispersion, the focal points for red, green, and blue light are closer together, so the lens exhibits less chromatic aberration. That’s why materials with higher Abbe numbers reduce chromatic aberration, while those with lower Abbe numbers increase it. This is also the principle behind achromatic combinations, where lenses of different Abbe numbers are paired to cancel dispersion effects.