Värihajonta

Värihajonta, known in English as chromatic aberration, is an optical phenomenon that occurs when a lens fails to focus all colors of light at the same convergence point. This is due to the fact that a lens refracts, or bends, different wavelengths of light by slightly different amounts. This dispersion of light causes colors to "fringe" or appear as halos around objects, especially in high-contrast areas.

There are two main types of chromatic aberration: longitudinal and transverse. Longitudinal chromatic aberration occurs when different colors focus at different distances along the optical axis. This results in colored fringes appearing either in front of or behind the plane of focus. Transverse chromatic aberration occurs when different colors are magnified by different amounts, leading to color fringes appearing at the edges of the image, even when the image is in focus.

Chromatic aberration is a common issue in simple lens systems and can be reduced or eliminated through the use of achromatic or apochromatic lens designs. These designs use multiple lens elements made from different types of glass with varying refractive indices and dispersion properties to bring multiple colors of light to a common focus. In digital photography, chromatic aberration can often be corrected in post-processing software.