What is spherical aberration caused by?

Spherical aberration occurs when light rays that strike the edges of a spherical lens do not converge at the same point as those that hit closer to the center. This optical phenomenon arises specifically from the improper curving of the lens surface. When a lens is designed with a spherical shape, ideally, all incoming light rays should converge at a single focal point. However, if the curvature is not executed correctly, light rays that enter the lens at different distances from the center are focused at different points, leading to blurred or distorted images.

This misalignment in the focusing of light creates a situation where the image quality is degraded, especially for objects that are either very close or very far away from the lens. Proper curvature and design of the lens surface can minimize this issue, making it a critical factor in lens design and optical performance.