Since the focal length f of a lens is dependent on n, it follows that different wavelengths of light will be focused to different positions. Chromatic aberration of a lens is seen as fringes of color around the image, because all colors cannot be focused at a single common position on the optical axis. However, there exists a point, called circle of least confusion, where this effect can be minimized.

Chromatic aberration can be further minimised by using an achromatic doublet or achromat in which two materials with differing dispersion are bonded together to form a single lens. This reduces the amount of chromatic aberration over a certain range of wavelengths, though it does not produce perfect correction.

Also, special glasses have been developed, notably containing the mineral called fluorspar, which have such a low dispersion that using two lenses already give a very good correction.

Optical engineers can design lenses that bring several colors to a focus at the same distance from the lens. Such lenses can be apochromatic, and can give sharper images than uncorrected optics. However, it requires extra pieces of glass in the optical path, and additional kinds of glass. This makes apochromatic lenses heavier and more expensive than their uncorrected counterparts.

An apochromatic lens is often called an apochromat, or apo, for short.