How Do Binoculars Work

Binoculars use a series of lenses, prisms, and elements to produce a clear view of distant things, places, and people. The two parallel optical tubes allow us to view with both eyes open, which is more natural and comfortable than using a spotting scope or telescope that requires keeping an eye closed. However, opening both eyes can maintain your depth of field and gives you a vivid and immersive experience where the scene takes on a more lifelike3D appearance.

Types of Lenses

1. Convex Lens:

A lens is a round-shaped piece of glass, a bit like a lentil (a dome). When a light ray hits the glass lens, it slows down and bends. If the lens curves like a lentil or a dome, so its outside is thinner than it’s middle and it is called Convex Lens. Light rays enter a convex lens and bend in towards the middle as if the lens is sucking them in. that shows a convex lens brings distant light rays into a focus. It is called Converging Lens because it makes light rays come together and makes things appear bigger.

2. Concave Lens:

The other kind of lens covers opposite way, with the middle thinner layer than the outside and this is called Concave Lens. A concave lens works light rays spread out like the lines of firework. Suppose light rays coming into a concave lens and after that shooting out in all directions. Therefore, a concave lens is also called Diverging Lens. These lenses are used in movie projects to bring the light from the film, spread out, and then cover the big area when it hits the wall.

The Optics of Binoculars and how they Work

If you wish to see something in the distance, you can use two convex lenses that are placed in front of the other. The first lens catches light rays from the faraway object and makes the focused appearance a short distance behind the lens. This is called the Objective lens because this is the nearest to the object you are looking at. The second lens picks up the image and tries to magnify it, as a magnifying glass magnifies an image on paper and this is called an eyepiece.

When light rays pass through a convex lens from a distant object, they cross over. That is why sometimes the distant things look upside down if you look at them through a magnifying glass. The second lens can’t sort out that problem so; binoculars have a pair of Prisms inside them to revolve the image through 180 degrees. The first prism rotates the image through 90 degrees while the other prism rotates it through another 90 degrees finally; the prism effectively turns it upside down. The prism can be organized in a back-in-back arrangement or at 9 degrees.

How Do Binoculars Work?

By principles, the binoculars are two small telescopes that are mounted side by side. They are hinged in the center so they can be detached and closed to fit different-sized focuses.

Do simply, the objective lens takes in light and captures an image and you will see that the second eyepiece lens magnifies the image and make it clear for your eye.  Let’s have a closer view of each part of this procedure to get a full picture of how binoculars work.

Light Refraction:

Light refraction is the way light bends when it goes through different objects, such as the glass in the objective lens in a set of binoculars.  The light turns as it goes through the objective lens. By changing the objective lens, binocular manufactures can control the light.

Lenses and Magnification:

In a convex lens like an objective lens, the middle is thicker than the outer sides. This causes the light to divert towards the middle, permitting the lens to focus distant rays of light into a small image that is planned a short distance away. The eyepiece is a magnifying glass that expends the small image into a larger one for you to view.

8-Power Binoculars: An extensive field of view

10-Power Binoculars: A closer and more detailed look


There is one problem with consuming these convex lenses to refract light. When light is diverted through a convex lens, the light rays can cross over and gives result in an upside-down image. And if you think the eyepiece lens takes care of this matter, but it does not. Prisms are engaged to rotate the image for your eyes. These prisms are just large wedges of glass that rotate and reflect the image. It takes two prisms to revolve the image 180 degrees, each prism effectively revolving the image 9 degrees.


Most of the binoculars are similar and they have the same functions of focusing. You will find a large center ring that can rotate to focus the barrels at the same is great for quickly focusing on an object and getting a clear image without much irritation. Several binoculars also include a diopter adjustment ring that allows you to focus one barrel alone from the other.

Field of View :

To determine the area of viewing the optics market represents a field of view. It is a measurement of how many feet across you can see with your binoculars. The measurement starts from 5 to 1000 yards and so on. Higher magnification shows the smaller field of view while the lower magnification larger field of view, you might not see as much detail, but you will be taking in a lot more.

Eye Relief:

Whether you are a regular hunter or a beginner Eye Relief has much importance while you are going to experience with binoculars. You may attempt to stick the eyepieces directly against your eyes but you need to have a short distance there so that the entire field of view is visible. What the exact distance you need to hold them from your eye is called eye relief. This feature has a lot of importance for you if you a user of eyesight glasses because if the eye relief is too small, you would not have room to get close enough to see the whole image without your glasses hitting the eyepiece.

Many optics manufacturers are introducing adjustable eyepieces that considered being a good thing in binoculars. The adjustable eyepieces will let you set the eye relief to whatever is most comfortable for you.

Exit Pupil:

The width of the light-ray coming through the eyepiece is called the exit pupil. If you observe you’re binocular and hold it from a distance before your face, you will come to know that there is a small round dot of light in the eyepiece. There are also some considerations of the small and large exit pupil. But keep in mind that how much the bigger is exit pupil, the bigger the image you will see. You can make an experience with the exit pupil in the low-light, where a small exit pupil prevents you from seeing clearly.

Binoculars for birding & Hunting:

If you are going hunting, your Binocular’s size and weight have much importance. You need compact binoculars with a magnification of 8 or 10 along with a lens diameter of 32 to 42. Birding and hunting are not much easier; an ideal pair of binoculars with the magnification of 8 will have a wider field of view that is a key to birding or hunting.

Water & Fog Resistant Binoculars:

Though the optics of binoculars is much important yet the feature of water and fog resistance is not less than that, because hunting is not a game that is played on some smooth and preplanned grounds.  If you are a regular hunter you know well the more the ways rough or tough the more you find the prey. A binocular must be waterproof and fog-resistant because of unexpected weather you may damage your gear.


Binoculars use a series of lenses, prisms, and elements to produce a clear view of distant things, places, and people. Binoculars have great value during your journey of hunting, hiking, golfing or climbing. It of users to view with both naked eyes, which is more natural and comfortable than using a spotting scope or telescope that requires keeping an eye closed. However, it gives you a vivid and immersive experience where the scene takes on a more lifelike3D appearance.

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