Chromatic aberration How does this optical defect occur?
Chromatic aberration is an optical defect that is reflected in photographs as a result of lens dispersion. It is also known as “color fringes or halos”, since they appear this way at the edges of a capture.
In other words, it is a visual phenomenon that occurs when the lens focuses different lengths of color on the same plane. In other words, the camera is not capable of taking these lengths within the same focal plane.
How chromatic aberration manifests
The manifestation of this aberration is not a consequence of objects in the real world, this is due to the use and technique of the camera. In other words, said optical defect can be avoided by applying a series of methods to avoid the appearance of color halos.
It is worth mentioning that the length of the colors and the focal plane are not the only elements that influence the appearance of chromatic aberration. It is also considered that the distance and the opening play a key point in the appearance of this defect.
In this sense, chromatic aberration is a phenomenon that cannot be detected at the moment of taking the photo, but only after it has been captured. More than anything in spaces with high contrast, and its intensity can be so high that it manages to ruin many photographs.
It is usual that when zooming in the image it looks blurry, or captured elements are shown with borders or colored spots composed of blue, yellow, violet, green and magenta.
However, these tones will not always occur at the same time during the shot, as it will depend on the type of chromatic aberration occurring in the photo.
Types of chromatic aberration
There are two types of chromatic aberration that depend on the refractive index at each wavelength when taking a photograph: longitudinal and lateral chromatic aberration.
Longitudinal Chromatic Aberration
This optical defect occurs when different wavelengths pass through the lens, but fail to converge at the same focal point.
This happens when the photographer uses a higher aperture rate to take advantage of natural light. Which causes distortion to be generated around each object or in the corners of the captures. The colors that usually occur in longitudinal chromatic aberration are blue, red, and green.
The best way to reduce this phenomenon is by stopping down the lens, or by using another aperture setting (f/1.2, f/1.4, f/1.8). Although this may slightly affect lighting, it will also prevent the formation of longitudinal-type chromatic aberrations.
Lateral Chromatic Aberration
This type of aberration occurs when lengths of color are focused at several different positions in the same focal plane. Unlike the longitudinal, it does not appear in the center of the image but in the corners, in spaces where the contrast is greater.
Likewise, the most frequent colors are green and purple tones and they appear with the use of wide-angle lenses or better known as “fisheye”. This defect occurs with most mobile device lenses, in which yellow and red are present within the chromatic aberration.