How To Choose The Right Binoculars For You

How to Choose The Right Binoculars For You

So you want to get binoculars? Great! Head down to your local sports store or jump online and order a pair with big numbers, spend the maximum you can afford, and you’ll be happy as can be. Eh! Wrong.

Ask Questions First

You wouldn’t call a shoe store and say “give me the biggest size you have that cost $100”. There are a few things you better be descriptive about. Say, men’s or women’s? Your particular size?… How about this one – What are you going to use them for?

When it comes to buying binoculars, you gotta know when, where, why and how you plan on using them.  For hunting? That’s a start. When? Early morning and evening when the light is low? Or, during the day in bright light? Are you in a blind, or moving? How far away do you want to see? Do you wear glasses?

How about for star-gazing, or bird watching? Maybe for whale watching, or just out hiking? What about to watch a football game from the upper deck? Or at a concert?  Hmmm, time to think about size and weight. And, do you need waterproof or water-resistant?


Here are a couple of guidelines that will make your purchase one you’ll be happy with.

  • Determine use
    • How, When, Where, Why, How Often, What do you need to see?
  • Set a price range
    • Without including night vision or range-finding binoculars, the cost range is anywhere from $30 to $9,300. Don’t let a low cost keep you from buying the perfect binoculars for your situation.

Binocular Definitions

Done? Great! Here are some definitions to help you pick the best binoculars for your use.


This is the first number used. General-purpose use ranges are from 7-10X. This means that objects appear that much closer.  A robin that is 100 yards away looks like it would at 10 yards with a 10X lens. Here’s the catch, as magnification goes up, your field of view (how much of something you see) goes down and shakiness goes up.


The second number is the diameter, in millimeters, of the main lens. Diameter determines how much light gets in. The larger the diameter, the more light and the heavier they are. The diameter should be at least 5x the magnification, so 10X binoculars should have a diameter of 50mm. Anything less means that there may not be enough light, depending on the amount of light available.


Some binoculars have a zoom function. For example, a 6-9×42 allows you to focus the magnification from 6x to 9x. The larger lens, known as the objective, is 42mm. Keep in mind that in this example, a 42mm objective would not allow as much light in at full magnification.

A few binoculars have diopter control, meaning that you can focus each lens individually. You’ll pay much more for this feature.

Besides being able to adjust the focus many binoculars also allow you to adjust each of the eyepieces for a better fit.  This is usually done by squeezing the two sides together and pushing them apart.

Eye Relief

Eye Relief is the distance you can hold the binoculars away from your eyes and still have a full field of view. Having a long eye relief, say of 16mm or greater, reduces eye strain and is critical if you wear glasses.  Look for an eye relief of 17mm to 19mm in order to capture the complete FOV the binocular was intended to show if you wear glasses or you will be looking through the binoculars for long periods of time.

Exit pupil

Hold a pair of binoculars away from your eyes about 10 inches. You’ll see a white disk in the center of each eyepiece.  That’s the light coming to your eyes. It should match the size of your pupils. As we get older, that size drops. My exit pupil at 50 years old is 5mm. My 25-year-old son has an exit pupil of 7mm. To find out what the exit pupil size is of the binoculars, divide the magnification into the diameter of the objective lenses. For example, 8×40 binoculars have an Exit Pupil of 5mm.


The two most common types of prism glass are the BK7 and BAK4. BK7 is the most common. The difference comes from the quality of the glass and how finely ground it is. BAK4 is considered better because it gives a round exit pupil, meaning you have a clearer picture. BAK4 prisms cost more and most common situations won’t need the difference. Be aware! There’s a difference between the barium-made and the cheaper Chinese phosphate-made crown glass.

ED and HD Glass

ED or extra-low dispersion glass lowers how much light separation there is. It reduces colored edges while giving clearer and sharper images. It also provides colors that are truer, greater contrast, greater resolution and better performance in low-light. Like all components, these come in different levels of quality.  Also, keep in mind that it takes more than just the glass to make a quality pair of binoculars.

HD or “High Def” is really nothing more than a marketing term for ED glass. Unless specifically noted, ED and HD glass mean the same thing. Some consider the highest quality glass to be FL, made of fluoride.

Lens Coatings

There’s nothing more frustrating, and hard on the eyes than looking across a body of water with the sun shining across it. That glare makes your binoculars useless unless they have a coated lens. The coating removes the glare and brings in more light. There are four levels of coating. With each additional layer of coating comes an increase in price.  Here’s what to look for:

  • Coated: A minimum of one lens with one coating
  • Fully-Coated: Each of the air to glass surfaces has a single layer of coating
  • Multi-Coated: A minimum of one lens with multiple layers of coating.
  • Fully Multi-Coated: Each of the air to glass surfaces has multiple layers of coating.

Porro Prism or Roof Prism

The Porro Prism binoculars are the original design. The eyepiece and the objective lens are not in a straight line. The Roof Prism binoculars are in a straight line. While this makes the Roof Prism ones more comfortable to hold and are more compact, you’ll have to pay more to get the same level of quality you’ll find in the Porro Prism design. The best bang for your buck, in the medium to low-cost binoculars, in terms of overall quality is found with the Porro Prism design.

Putting it All Together

Now that you know what your options are, you probably have a good feel for what you need. Let’s look at some common uses and recommendations.

General Purpose – let’s define these as the binoculars you keep in a drawer, at home. You pull them out every once in a while to look at a bird in your yard during the day or take with you on an occasional hike.  Choosing a lighter, compact, set with an adjustable range of magnification from 7-10X with an objective of at least 42, will provide you a good solution at well under $100.

Bird Watching – there are a lot more choices here. For general birdwatching, during the day in dry weather, a roof prism with at least 8X magnification and an objective of 42mm is a good start. Keep in mind that you want a good field of view to help you spot the birds. Most birders recommend water-resistance also. Use 10×50 or 12×50 for greater detail of smaller species at a distance.

Hunting – for low-light situations be sure the objective is at least 5X or greater than the magnification. If you are looking at long-range shooting, say over 300 yards, consider fully multi-coated, 12 X 60, with ED glass and a tripod as a mount. If hunting under 200 yards, during the day, choose magnifications greater than 8 and a 40mm objective. Make sure they are waterproof and fog proof!

Star-gazing – high magnification and a large objective lens are required. A magnification of 15 or greater, with a diameter of 70mm, will be found on your top-end glasses. Yet, many people who just want to scan the skies will choose a lightweight 8×42. When considering a high-end set, buy with your exit pupil diameter in mind.


Weight and ease of use are important factors. Consider the compact (roof prism) binoculars with a wide-angle are best. 4×30, 5×25, 8×25 and 7×18 or 7×21 are all great for the opera, theater and concerts.

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