Binocular Vocabulary

May 03, 2018 - By Hayden Outdoors

Decode Basic Technical Jargon Associated with Consumer Optics


A good pair of binoculars is a must-have for a landowner, the kind of essential gear that should always be close at hand to provide a better look at livestock and wildlife, scan for predators, or check fence conditions from afar.


“Binoculars Seem Simple Enough”

Look through the lenses and what’s far away appears close. However, when shopping for binoculars, consumers often find just enough technical lingo, rooted in the vernacular of optical engineering, to find the process intimidating. Buyers shopping for a basic set of binoculars can benefit from some decoding of the most common technical terms.



Binoculars will be described with a set of numbers – for example, “7×35.” The first number refers to magnification; in this example, the binoculars would show the subject seven times closer than it would appear to the naked eye.


Objective Diameter

That second number – the “35” in the above example of “7×35” – refers to the lens diameter, the measurement across a binocular lens; the larger the number, the larger the lens; a larger lens allows in more light, providing for a brighter view.


Field of View

This might be described as a linear measurement, in feet or meters, or as an angle, in degrees, and indicates the width of the area that will be visible through binoculars. In general, the greater the magnifying power, the narrower the field of view.


Eye Relief

The distance between the back of the eyepieces and the user’s eyes when the user has a clear, “un-vignetted” view through the binoculars. This is a particularly important detail for users who wear glasses. As a means of reference, longer focal length generally means greater eye relief.


Image Stabilization

When using high-powered binoculars, users might struggle to keep an image steadily in view. Higher-end options can come with image-stabilization technology that helps lessen the effects of an unsteady hand. On the downside, binoculars with such technology tend to be heavier than options without it.


Anti-reflective Coating

This helps prevent a hazy, low-contrast view of a subject, caused by lenses “losing light” due to reflection.


Range-finding Capability

Look through binocular lenses and you might see a superimposed scale showing the angular height of the subject in view. With a fairly basic algebra formula, a viewer can use that scale to estimate the range, or distance, to the subject, if that subject’s height can be estimated. That formula:

Distance = (Estimated Height/angular height of object) x 1000


The Ultimate Landowner Utility

Once a landowner begins using binoculars, it can be hard to live without the utility they offer. Having a set of binoculars in the home and in every vehicle can help meet the unpredictable need to get a quick, up-close look at a trophy elk, an injured horse, a trespasser, or a distant gate that appears open. Equipped with a basic understanding of the technical specs associated with binoculars will help ensure a consumer is properly equipped.