Chromatic Aberration in Photography!

(Last Updated On: August 24, 2021)

Chromatic Aberration in Photography!

Chromatic aberration is the parasitic dispersion of light passing through the optical system. It can occur due to the lens or improper refraction of light when photographing. Chromatic aberration leads to a decrease in the clarity of the image and sometimes the appearance of colored outlines, stripes, and spots absent in the subject. In addition, although modern lenses and cameras are developed using technologies aimed at reducing such glitches, the fact remains – they still pop up in our images.

Chromatic aberration is a common optical problem when a lens cannot transmit all color rays to one focal plane, or different color rays are focused on other points on the same focal plane. The cause of chromatic aberration is that the objective lens has dispersion; light waves of different colors pass through it at different speeds. In practice, this is manifested because the image is blurred, and around some objects, a colored “fringe” is formed – an outline of red, green, yellow, or purple.

Ideally, the lens should focus all light waves at one point, where the so-called minimum geometric scattering region is present. However, in reality, the refractive index is different for waves of different lengths, which means that waves of different colors intersect at different points of the same plane or in other planes. The result of this is the emergence of aberrations of one type or another. There are two main types of aberration: longitudinal and transverse.

During photography, the transmission of light varies and affects the frequency. When light passes through the lens, different wavelengths (colors) move at different speeds and are fixed in various places on the sensor. Often, improper use of a lens for a specific shooting can cause chromatic aberration. As a result, red, green, and blue do not converge at the desired point and create a display of channels that do not match.

Aberrations, or distortions, are geometric and chromatic (color). With geometric ones, everything is straightforward; you can and should fight with them if this is not an artistic idea. In modern lenses, geometric aberration, also called distortion, is primarily corrected by an “aspherical” element. That is a lens with a more complex profile than a spherical one.

You can successfully correct the residual distortion in the editor. However, with chromatic aberration, everything is a little more complicated. The nature of chromatic aberration in glass dispersion. Dispersion is different refractive indices for different wavelengths.

In the latest generation cameras, the processor automatically corrects chromatic aberrations at the stage of converting to JPEG. Either way, you better think about what you are photographing, not how much your lens is prone to anomalies. A lens without noticeable aberrations contains many expensive low-dispersion and aspherical elements; therefore, it is much more costly than its counterparts with aberrations.

In addition, a variable focal length (zoom) design is much more complex than a fixed focal length design, as aberrations appear differently at different focal lengths. That is why “fixes” are of higher quality and cheaper than “zooms.” The presence of ED elements in Nikon lenses is marked with the letters ED. If you see ED in the lens markings, then you can forget about chromatic aberrations.

 

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