Compound lens' focal length


A lens is a transmissive optical device which affects the focusing of a light beam through refraction. A simple lens consists of a single piece of material, while a compound lens consists of several simple lenses (elements), usually along a common axis.
A compound lens is a collection of simple lenses of different shapes and made of materials of different refractive indices, arranged one after the other with a common axis. If “thin” lenses are placed in contact, then the combined focal length of the lenses is related to its one of the focal lengths.

Related formulas


fCompound lens' focal length (m)
f1Focal length of one of the lenses (m)
f2Focal length of the other of the two lenses (m)