This lens is at the end of the binocular away from the eyepiece. It gathers light to the eye.
is the lens in the eyepiece. It is usually smaller than the objective
lens except in the case of some roof prism binoculars.
objective lenses of a binocular with ruby coatings will be a bright
reddish-orange. Since red light is reflected the colors seen through
binoculars with ruby coatings are skewed to the cool end of the
Another result of using ruby coatings is a shortened color spectrum
which may increase the contrast and resolution of a binocular.
a roof prism binocular the light waves are reflected off the surfaces
and split into two out-of-phase beams of light. Application of a phase
correcting coating forces the light back into phase.
Note: Phase correction in a binocular greatly enhances color fidelity, also affecting brightness, contrast and resolution.
Porro Prism Binoculars
The Porro prism binocular has the "traditional" binocular appearance with offset prisms for image-erecting.
Roof Prism Binocular
The image-erecting prisms of the roof prism binocular are lined up for a compact, durable binocular body.