When does spherical aberration occur?

Spherical aberration occurs when light rays pass through the edges of a lens due to the shape of the lens itself. In an ideal lens, all light rays would converge at a single focal point. However, lenses that have a spherical shape do not bend all incoming rays of light equally. Rays that pass through the center of the lens focus correctly at the focal point, but rays that pass near the edges are refracted at different angles. As a result, these rays converge at points that are further away from the intended focal point, leading to a blurred image. This effect is especially pronounced in lenses that are not designed to correct for spherical aberration.

The other options do not accurately describe the phenomenon of spherical aberration. When light rays are perfectly focused, this indicates an optimal lens performance without distortion. Complete absorption of light involves light not being transmitted at all, and when light rays diverge, it generally pertains to scenarios involving convex or concave shapes but does not define the specific aberration caused by spherical lens shapes.