...your guide to using optics.

Binocular Terms: (O - Z)

Objective Lens

This lens is at the end of the binocular away from the eyepiece. It gathers light to the eye.

Ocular Lens

This is the lens in the eyepiece. It is usually smaller than the objective lens except in the case of some roof prism binoculars.

Ruby Coatings

The 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 spectrum.

Note: Another result of using ruby coatings is a shortened color spectrum which may increase the contrast and resolution of a binocular.

Phase Correction

In 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.

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