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A Brief Guide to Understanding Binocular Specifications and Their Capabilities

Binoculars are some of the most useful and versatile optical tools ever made. However, not all binoculars are alike, so it’s important to understand the differences among binoculars and the various specifications that define their capabilities. Below is more information that can help you effectively evaluate binoculars.


One of the first specifications that binocular buyers often ask about is the power or magnification of the binoculars. The power is expressed in terms of how much closer a given object appears in the viewfinder.
For example, a five-power (5x) pair of binoculars will give the impression that the target is five times closer than it really is.
High power can be important for certain uses, such as for distant observations of game animals, but keep in mind that increased magnification comes at a cost. Not only are higher powered binoculars often more expensive but they are also heavier and more difficult to use.
Only buy the power you need, as too much power at a higher cost may be unnecessary for your specific activity.


The other major specification that classifies binoculars is objective. This measurement, which is expressed in millimeters, is the diameter of each front lens. A larger objective means the pair of binoculars has more light-gathering capability than binoculars with a lower objective. This feature is important to users, as the brightness of the view is directly affected by objective.
Higher objective comes into play for users who need the light-gathering capability for specific tasks. For example, astronomers often use binoculars instead of telescopes for general stargazing, and a high objective is invaluable in making deep, dim objects visible.
Increased objective will also raise the price of binoculars, but many more users will profit from higher objective as opposed to increased power.

Angle and Field of View

Two other specifications that provide important information about binoculars are angle and field of view. The first, angle of view, expresses how much of a 360-degree circle can be seen when looking through the binoculars.
For example, imagine yourself standing in the middle of a circle and looking outward; if your binoculars have an angle-of-view of six (6.0) degrees, then you are able to see a sliver of the circle that represents 1/60th of the total.
A related specification, field of view, refers to how much of a scene can be visualized at a distance of 1,000 meters from the observer. For example, if your binoculars have a field of view of 50 meters, then that means the observed scene will be 50 meters across when looking from 1,000 meters away.

Lenses and Prism Arrangement

Binoculars use lenses and prisms, which are precisely engineered pieces of optical glass, to shape incoming light and form the image seen by observers. There are two common arrangements of lenses and prisms in modern binoculars: porro and roof systems.
The porro system utilizes a cluster of offset prisms, and this arrangement gives binoculars their familiar shape. The other option, known as the roof system, has a straighter arrangement of prisms and lenses, and this arraignment creates a sleeker pair of binoculars.
Both porro and roof system binoculars are fully capable of providing excellent views, so visual performance is not the deciding factor for buyers. Instead, roof system binoculars have an advantage in terms of their size and improved user comfort. Roof system binoculars also cost more, so if you are able to handle the bulkier shape of porro system binoculars, you can save money by purchasing this traditional style.

Housing and Construction

Binoculars are made from a variety of materials, including aluminum, plastic, and magnesium. These materials and construction details determine how rugged binoculars are and if they are able to withstand abuse or other conditions.
For example, some binoculars are waterproof and can withstand full immersion. Others may use special gases inside the sealed optics compartments to make the binoculars fog resistant. All of these added features add to the cost of the finished product.
If you aren't sure what you need in a pair of binoculars, then take a few minutes to visit with a specialist in binoculars and other optics. This expert can provide you with guidance and help you select the best binoculars for your needs.