How can coma in optical systems affect image quality?

Coma is a type of optical aberration that occurs when off-axis points of light are not focused correctly, leading to distortion in the image. Specifically, coma results in the blurring of points that are out of focus, which makes them appear elongated or smeared rather than sharp dots. This effect can significantly degrade image quality, particularly in wide-angle lenses and systems with large apertures.

When an optical system is affected by coma, points of light that are located away from the center of the field of view do not converge to form a clear image. Instead, they are elongated and can exhibit a tail or streaking effect, resembling a comet—a characteristic that gives the aberration its name. In practical terms, this means that when viewing objects with fine details or bright points of light, the image can appear less defined, resulting in a loss of clarity and detail.

In contrast, other effects like sharpening image focus or improving color accuracy are not connected to the nature of coma and its impact on light convergence. The starburst effect is also not a result of coma but instead arises from diffraction or certain lens designs. Therefore, the blurring of out-of-focus points directly relates to how coma disrupts the intended image formation in optical systems, confirming that