A zoom monocular is an adjustable optical magnification instrument intended for use with one eye. Zoom monoculars are often used by hikers, hunters, and soldiers to see clearly over long distances. The narrow end of the zoom monocular is usually held to the eye socket as the lenses are rotated into focus, much like a sea captain's telescope. Fixed power monoculars are restricted to one particular magnification setting and cannot be adjusted like zoom monocular varieties. Many zoom monoculars have secondary features like laser range finders and night vision capabilities.
Portability and function can make a quality zoom monocular the superior option for anyone on the move. Monoculars are available with zoom distance ranges to meet almost any sporting or military personnel need. Bulky binoculars are often worn around the neck and can become an annoying weight burden after hours of wear. The small and lightweight zoom monocular often has all the capabilities of a pair of binoculars at less than half the size and weight. Most zoom monoculars are small enough to fit into the pockets of a pair of pants or slide into the side pocket on a golf bag.
The majority of zoom monoculars have multiple adjustment zones for magnification control and fine focus. Changing the position of the control moves lenses and alters the visual delivered through the monocular. The fine focus ring is often positioned near the narrow eyepiece end of the zoom monocular. Magnification adjustments are usually made by turning the wider end of zoom monoculars to move the largest lens back and forth. More specialized and powerful monoculars may have additional adjustment controls to set light levels and other features.
Zoom monoculars with enhanced features are useful in more situations and can often provide additional helpful information. Night vision capabilities make it possible to multiply the available light entering a zoom monocular in low light situations. Early morning and late night excursions can render a monocular without night vision practically useless. Laser range–finding technology gives the user a distance reading on the target they view through a monocular. Understanding the distance of the viewed scene is useful for making estimations of scale and a fully informed field decision.
Most zoom monoculars do not pull open and collapse closed like the common folding telescope. Powerful compact lenses in a zoom monocular are capable of projecting distant images. Many monoculars can be concealed in the hand for use without giving away a location.