How Do Binoculars Work: The Function of Prisms

How do Binoculars Work

A Binocular is a must-have accessory for every one of us who is a keen traveler and loves to adore the natural beauty of animals without even getting closer to them. Generally, a binocular is a set of two telescopes which assist the viewer in accurately pointing in any direction.

This device is based on a simple principle that is to make distant things appear closer and clearer. Binoculars may look similar, but there is a massive difference between every pair. From the thickness of the lens to its shape and curve, everything has a great impact on the type of view and distance covered.

Before jumping on the thorough guide of how to select a pair of binoculars, you should know how binoculars work.

The Working Process of Binoculars

Binoculars have two specific lenses that are mounted on each end. The core purpose of these lenses is to accumulate the light from the destination object at which the user is focused. This light is then transmitted to the receiver’s end and the user gets a clear and a zoomed image of the object.

The image generated by the lenses is in upside and backward position, but the user is able to see it in a proper way. Here’s how?

Prisms are small glass blocks that are amalgamated with the binocular lens. With the help of a small prism, the viewer is able to see the correct image in the perfect orientation. This is one of the core reasons why prisms are used in binoculars.

What is The Function of Prisms in Binoculars?

What is The Function of Prisms in Binoculars

Binoculars manufacturers use two types of prisms in their product i.e. Porro prisms and roof prisms. Roof prisms are used by the manufacturers which are indulged in lightweight and smaller binoculars.

The core principle of roof prism is to substitute the light into two pieces and couple it again for a clear view. This whole process of substituting the light and joining it again is termed as phase shifting. In the case of roof prisms, the viewer will face less contrast, because less light is transmitted from the main lens to the eyepiece.

When talking about Porro prisms, the working is completely distinct. These kinds of prisms offer a wider and better view than roof prisms. Porro prisms are based on an offset arrangement to align the eyepiece lens and the objective lens.

A great binocular set is indispensable for a fantastic view but buying the perfect one is next to daunting. Here is a thorough guide that will assist you in purchasing the best product.

Diameter of Lens

A diameter of a lens is the most imperative thing to look for before buying a binocular. The compact sized binoculars have 25mm lens diameter whereas the regular ones are 32mm to 42 mm in diameter. Bigger lenses have a dramatic significance and can enhance the performance in low light conditions.

Type of Glass

There are a plethora of glasses used by binoculars manufacturers and every glass type has its own significance which can affect the quality of the image in a huge way. You can consider a set of binoculars that are manufactured with FL (fluoride) and ED (extra-low dispersion). These glasses can help you with a clean image by terminating the abbreviations and less fringing of colors. (Fringing refers to the blurring which occurs in-between the darker and brighter parts of an image).

Prism Type

As discussed above, there are mainly two types of prism used by binoculars makers- roof and Porro prism. A Porro prism produces an image that is clearer and crisp looking than the casual roof prism. If you are a professional and want to purchase the right product, then settling down with Porro prism binoculars is suggested.

Other Factors to Consider


The weight plays a very important role in the choice of binoculars. If you buy a device that is bulky then you will not be able to hold it for longer durations and it will be hard to focus in a certain direction.

Field of View

The field of view means the area that can be seen through the binoculars. The larger the field of view is, the better the binoculars are. (Keep in mind with an increasing field of view- the price of binoculars also increases).

How Far Can You See With 10×50 Binoculars?

Binocular specifications are dependent on the type of view you want to have. In the case of 10X50 binoculars, you will be able to spot things that are located within a distance of 2 KM. In order to spot things at a far distance, consider having 20X or 16X binoculars.

Wrap Up

With each day passing, binoculars are becoming better. New models are much improved and can help with a better vision. Some binoculars even have infrared technology for outstanding night vision. So, get yourself a new pair looking upon the factors mentioned above.

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