How do Binoculars Work? Leave a comment

Binoculars contain a magnification lens and a prism in each ocular. The lens performs the actual magnification of the object you are viewing. The purpose of the prism is to present the image right-side-up and in the correct direction. Without the prism, the image would be backwards and up-side-down.

How Binoculars Work

Binoculars are built in two basic designs – Porro prism and Roof prism style. The design that you choose depends partly on how they feel in your hands to what they can do. Roof prisms binoculars are a more-powerful category of binoculars. When binoculars are more powerful, it is necessary to have the oculars closer together at all times to hold the image steady. They are more powerful from the onset but are less adjustable and it is harder to hold the image steady for viewing.

It is far easier to view steady image with Porro prism binoculars because they are larger. There is a bigger hinge between the oculars that offers a much wider range of adjustment. They are also much larger and therefore easier to hold in your hands. Porro prims binoculars have less-powerful lenses. While they will have less distance than Roof prism binoculars, they are easier to see things with. It is far easier to get a steady view of an image with a less-powerful lens.

What do the numbers mean? The numbers that identify binoculars, like “8 x 42”, are magnification specifications (a.k.a. “mag specs”). They describe the manner in which the binoculars view the object or the terrain you want to look at. Specific mag specs are good for specific areas and situations.

The first number tells you how many times the object’s size is multiplied in your lenses, so “8” means the object will appear eight times closer to you than it is; it is easier to hold an image steady with binoculars that have lower mag specs. The second number is the physical diameter of each of your lenses, measured in milli-meters.

Binoculars are constructed to be air-tight and must not be dropped. If the air-tight seal is broken, they interior of the ocular will quickly collect moisture, get foggy and be unusable. Many binoculars nowadays have oculars filled with nitrogen to help keep the oculars clear and prolong the useful life of the instrument. The design of binoculars is basically the same as it was 80 years ago but each component, and the process construction of binoculars, has become ever-more precise.


Why Procular?

If you love the outdoors and always keen for a closer look then you’re in the right place! Featuring a huge selection of binoculars, telescopes, spotting scopes, monoculars and night vision – Procular’s got you covered! Be sure to checkout our expert buyer guides to see which product is right for you:


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