Spherical Aberration Calculator

About this calculator

Spherical aberration is an optical defect where light rays striking a spherical mirror or lens far from its center focus at a different point than rays near the center — the mirror simply can't bring every ray to one perfect focus. Longitudinal spherical aberration (LSA) measures how far along the optical axis that focus point shifts, approximated for a spherical mirror as LSA ≈ h² / (2·R), where h is the height of the ray from the axis and R is the mirror's radius of curvature.

This approximation is a standard tool in optics and telescope design: it's the reason amateur and professional telescope makers often favor parabolic mirrors over cheaper spherical ones for large apertures, and it's used to estimate image blur before deciding whether a design needs a corrector lens or a different mirror shape.