Periscopic lens

Ica Periskop

A periscopic lens is a symmetrical lens, consisting of two equal periscopic convex lens elements and the aperture between the elements. The periscopic lenses have no correction of chromatic aberration, are free from distortion and maybe a little faster than the simple color corrected achromatic lenses. According to Ludwig David periscopic lenses were the cheap lenses for the poor.

Glossary Terms