How To Choose Binoculars

Having binoculars on a trip into the outdoors can make your time more pleasurable. Learn what you need to know to get the right pair.
The Mountaineers The Mountaineers
May 16, 2018
How To Choose Binoculars

Having binoculars can make any trip more fun and memorable. At The Mountaineers, we aren't experts in the technology that goes into seeing far away, but lucky for us, our friends at Binoculars Today like to share!

Binoculars are easy to find, but sifting through all of the technical jargon and figuring out which pair is best for you can be intimidating for a beginner. To make things easier, here's a comprehensive buying guide that discusses the specifications and factors you need to consider before buying binoculars.

How to choose Binoculars

How to Choose Binoculars

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Understanding binocular specs & features

What do the numbers on binoculars mean?

The first thing you notice is two numbers (ex: 7X35, 10X50). The first number 7 (in 7X35) represents magnification. Its 7  times zoom, so the object appears 7 times closer than it is. In 10X50 binoculars, the object appears 10 times closer. The second part of the number, 35 (in 7X35) represents the diameter of the objective lens in millimeters. The objective is the larger lenses away from the eyepiece.

As the magnification (first) number increases, the object appears bigger but the field of view gets narrower, making it harder to focus or stabilize. If you pick one with higher than 10 times zoom, you will need a tripod or monopod.

As the objective lens size (second number) increases, more light gets in and the image gets brighter. Small objective lens sizes are better for low light activities, but the binocular gets bigger and heavier.

Most binoculars fall in range 30-50mm objective lenses. Compact binoculars have less than 40mm lens. Astronomy binoculars have greater than 50mm lens.

Eye relief

The eyepiece should be at a comfortable distance from your eyes while viewing. The distance of the eyepiece from your eyes when viewing is called ‘eye relief’.

  • 5-15mm distance from eyes is comfortable for normal viewing
  • 12-15mm eye relief if wearing glasses

Porro Prism Vs Roof Prism

Porro Prism and Roof Prism differ in how they send light from the objective lens to the eyepiece.

Porro Prism is older, and have been around since World War II. These are “A” shaped, and they are generally cheaper but bigger in size.

Roof Rrism is newer. These are “H” shaped, and they are generally a little costlier but more compact.

Field of View

Field of view is measured in feet at 1,000 yards. Ex: 380 ft at 1000 yards. Its also represented in degrees. Ex:  Angular field of view – 6.1 degrees. As the magnification increases the field of view decreases.

Glass grade

  • BAK4 (barium crown glass) is the costlier option and is most effective.
  • BK-7 (borosilicate glass) is also good, but the light at the edges is low and the view is a bit like a square.

Lens coating

Lenses and glasses are applied with anti-reflective coating. These are coated to prevent the light that falls on the glass from reflecting. 

  • Coated (C) – Some glasses are coated.
  • Fully coated (FC) – All glasses are coated.
  • Multi-coated (MC) – Some glasses are multi-coated.
  • Fully multi-coated (FMC) – Fully multi-coated.

Focusing ability

Binoculars focus in two ways.

  • Centre-Post Mechanism – Both the lenses are focused by the common central control.
  • Individual Lens Focusing – Each lens has a separate control.

Image stabilization

Image stabilization is a recent addition to binoculars, and manufacturers use the same technology found in cameras to stabilize the image. There are two main categories.

  • Active: These use electronic sensors and adjust some part of the view to correct the shake.
  • Passive:  These use an internal gyroscope to minimize the shake from the hand of the holder. 

Night Vision

If you are more of a night person and you use binoculars for watching nightlife or hunting in the dark, you could choose the binoculars with night vision. These optico-electronic devices work by amplifying the available light. Some night vision binoculars come with digital cameras,which record/shoot low-quality images/videos with very minimal magnification.

Understanding your requirements

There are so many models available on the market that each option is better designed to suit some specific activity. While some are good for bird watching, others are handy while hunting, and others have better night vision ... and so on. So while looking at the specifications and other features, keep in mind the activity for which you are going to use your binoculars the most.

Binoculars for Sports, hiking & Birdwatching

This is the most general use of binoculars, and most of the binoculars on the market fit into this category. For these purposes, one prefers to have compact and lightweight binoculars so that it is easy to carry around. At the same time, the power of the binoculars is also equally important.

Binoculars with the power 8x to 12x and objective lens of 25mm to 50mm are preferred for this purpose.

Binoculars for Stargazing – Astronomy

Most people usually overlook binoculars for stargazing, but binoculars are smaller and have certain advantages over telescopes. Unlike telescopes, you don’t necessarily need to have a tripod for binoculars. Good astronomical binoculars are cheaper than basic telescopes and are a good start for beginner astronomy enthusiasts.

Astronomy binoculars need high magnification power. Usually, a magnification greater than 12x is preferred. These are bigger and bulkier that standard binoculars. Sometimes you would need a tripod to comfortably use these for a long time.

Other things to consider


You can get decent binoculars for under $100, and the features and the quality increase as you invest more money. In general, very good binoculars with high-end features will cost $200-$500.

Would you need a tripod/monopod?

If you are going for very heavy binoculars with magnification greater than 10X, chances are you might need a tripod or a monopod to be able to hold such heavy binoculars for a longer time. Usually, binoculars used for astronomy would need a tripod. Even some bird watchers use tripods.

Additional accessories

Carrying case, eyepiece and lens protection covers, cleaning cloth, binoculars neck strap – these are some basic accessories you would need along with your binoculars. If you are going with night vision binoculars or binoculars with a camera, you will also need a power cable and memory stick. Some binoculars come with accessories included. 

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Dominique Blachon
Dominique Blachon says:
Feb 07, 2022 11:23 PM

" Small objective lens sizes are better for low light activities, but the binocular gets bigger and heavier." ==> shouldn't this be >LARGE< objective lens sizes...? 50 mm and above are better for low light.