undercorrected

Updated: January 24, 2026

Any irregularity in the shape of the rings which persists after the lenses have been accurately adjusted and the telescope has properly cooled may be ascribed to imperfections, such as veins or spots of unequal density in the glass forming the objective. The spherical aberration of an object glass may be undercorrected or overcorrected.

Garrett Putman Serviss - Pleasures of the telescope: An Illustrated Guide for Amateur Astronomers and a Popular: Description of the Chief Wonders of the Heavens for General: Readers