Street Photography Magazine

C

hromatic aberration is a widespread

phenomenon that occurs in both

contemporary and legacy lenses. The term is

used to describe a number of different types

of focusing errors.

Spectral Colors

Whether you use high-end or cheap

equipment, most lenses display one sort of

chromatic aberration or another. Regardless

of exactly how they are formed, chromatic

aberrations are always caused by light of

different wavelengths being refracted to

differing degrees. The individual elements in

a lens not only direct the incident light but

also split it into its component colors the same

way that a prism does.

This article introduces various types of

chromatic aberrations and explains how to

distinguish them from other types of optical

errors such as sensor blooming or flare. We

also test a range of dedicated software tools

designed to correct lens errors.

Axial and Transverse

Aberrations

Generally, we distinguish between

longitudinal (axial) and transverse (lateral)

aberrations as seen in relation to the optical

axis of the lens. Both types can cause false

colors and halo effects, but have

fundamentally different characteristics.

Fringing

Lateral color errors often occur at the edges of

images because the images of red, green and

blue spectra are reproduced at slightly

different sizes. This causes color fringing,

which is especially obvious at high-contrast

edges. The further a point is from the center

of the image, the more prone it will be to this

type of error, whereas fringing doesn’t occur

at all in the center of the frame. Stopping the

aperture down neither reduces nor increases

the likelihood of this type of error occurring.

All non-radial high-contrast edges are

likely to suffer from fringing. Sure-fire sources

of this type of artifact are subjects at the edge

of the frame that contain thin black lines

against bright backgrounds, such as the

leafless branches of a tree in the snow or a

chain link fence shot against a bright sky.

The color of a fringing artifact depends on

whether it occurs at a dark-to-light or a

light-to-dark transition, seen relative to the

center of the frame.

Lateral aberrations are relatively simple

to correct, provided a couple of basic

preconditions are met. You need to know in

detail about the specific optical characteristics