ESSENTIAL SKILLS

How to Choose Binoculars: With Great Power Comes Great Vision

How to Choose Binoculars
Russell McCarty
Written by Russell McCarty

Do you love hunting or bird watching? Do you simply adore nature observation or hiking? Is stargazing more your thing? We bet you share at least one of these passions with us. Then you just need a good pair of binoculars to help you see better. But first, you should find out how to choose binoculars because different models suit different purposes.

So each characteristic of the binoculars will tell you something about its abilities and about the activity you can use it for. But there are a lot of specific features to take into account, like the lens diameter, the magnification, the coating or the materials used. Those are just a few since there are others, equally important. So how can you navigate this sea of very technical information in order to make a good choice?

How to Choose Binoculars

Well, we have your back. We’re going to untangle all these details together, we’ll try and explain everything in simple terms so you can understand how binoculars work. After that, we’re confident that you can apply all this info by yourself when you’re analyzing actual products on the market. So read on, we’ll make it worth your while.

Materials

The materials used are extremely important because they’ll show you how resistant your binoculars are. Metal-made binoculars from magnesium and titanium are great in terms of durability and ease of use even at very low temperatures, with no optical distortion. However, these will cost more, though you will likely use them for longer.

Bnoculars Material

Besides, polycarbonate reinforced with glass fiber is renowned for its great ability at withstanding shocks. On the other hand, plastic binoculars are less resistant, although they’re generally lighter and cost less. But if you’re willing to invest more in your binoculars,  a magnesium pair’s weight is on par with that of a plastic’s pair.

Magnification Power

There are two different numbers you’ll see on the specifications sheet, written like A x B mm. A is the first number and shows how close or bigger your target appears. Say you have an 8x 42 mm binoculars. The 8x shows you’re seeing it 8 times as close as it really is.

How can you put that into practice? If you’re varmint hunting with an 8x binoculars and the varmint is 400 yards away, you’re actually seeing it as if it would be 50 yards away. So you’re dividing the distance by the magnification to see the perceived distance.

Binoculars Magnification

A bigger magnification is also correlated with a decreased field of view, meaning that you’ll see enhanced details at the cost of less of the surrounding area. A bigger magnification means you’ll have to keep the binoculars pretty steady as your hands moving can mess with the image.

Lens Diameter

This is the second number in our example above, so 42 mm. The lens diameter is always expressed in millimeters and it shows you how big the lenses objectives are. We’re talking about the exterior lenses, not the ones that are closer to your eyes.

Binoculars Lens Diameter

So, lenses have the purpose of letting the light pass through them and amplifying that light to make things appear closer. The more light passes through the lenses, the crisper the end result. So if you plan on using your binoculars in low light conditions, you should choose a bigger lens diameter.

Exit Pupil

We’re not done with numbers yet, but this one is extremely important for image crispness in environments with low light. This number is calculated based on the other two dimensions, by dividing the lens diameter by the magnification. So with the 8x 42 mm binoculars, the exit pupil is 5.25 mm.

The exit pupil shows you how bright the image will be, so you should go with a bigger exit pupil if you want crisper images. If you choose a larger exit pupil, you will also get a steadier pair of binoculars against most on-field shakes.

Binoculars Exit Pupil

This is not just an artificially chosen feature, it’s really important to understand how it works. So, at dusk or dawn, when the light is very low, human pupils can dilate to 7 mm. Basically, binoculars with an exit pupil of less than 7 mm are minimizing the amount of light that gets to your eyes when it’s very dark.

Basically, make sure you get at least 5 mm for the exit pupil if you’re using the binoculars in low light. Otherwise, you can mostly use the binoculars for daytime activities, when the human pupil is around 2 mm wide.

Relative Brightness

From magnification and lens diameter to exit pupil and relative brightness, everything is connected. Since we’re off to such a good start with our math, let’s make one more calculation. So square the number represented by the exit pupil and you get the relative brightness. In our example above, multiplying 5.25 mm by itself gets us to 27.56 mm2. Yes, we used a calculator.

Binoculars Brightness

So we already discussed how a bigger exit pupil means increased image crispness. It stands to reason that a bigger relative brightness will also be correlated to an increased image brightens. However, the relative brightness is also impacted by other product characteristics, like lens design and coating.

Eye Relief

We’re not done with numbers yet, but at least we’re not doing any calculations. The eye relief shows you how far apart your eyes and the eyepieces are at full field of view. A longer eye relief means you can hold the binoculars further away from your face without affecting the field of view.

Good for the eye relief

A longer eye relief is therefore extremely comfortable in at least two situations: when you’re wearing glasses and when you’re not staying still. The movements of a boat or of you walking downhill might require you to keep some distance between your binoculars and your face. So for these situations, aim for an eye relief that’s at least 12 mm.

Field of View

This is another important spec, and you can see it expressed in feet at yards or in degrees. The first one is the linear field of view, showing you how wide your scope is from left to right. You will also possibly read the angular field of view in the official scope, showing you a more precise angle that is covered by the pair of binoculars.

Binoculars Field of View

The field of view is connected to the magnification, as we’ve explained before, so a narrower field of view may be the result of a bigger magnification. But the eyepiece design impacts the field of view too so that a wide angle eyepiece that’s more expensive offers an increased field of view.

Focus

This is a feature of most binoculars on the market. There’s a sort of wheel or a knob in the middle that can focus both the barrels simultaneously. There’s the diopter adjustment ring too, but this one can only focus the barrels one at a time, which is extremely important if your eyes have vision differences.

Binoculars Focus

And don’t forget the matter of the minimum focus. That’s the shortest distance for which your binocular can focus, so the binoculars can never focus on something that’s closer than this distance. If you’re into bird watching, this is a useful detail.

Prism Type

The binoculars on the market have different designs, but they all magnify the image. However, the lens system has to be based on prisms because otherwise, the magnified image would look upside down when the light rays get through the lenses.

The Porro prism design is one such possible construction, and we appreciate how wide the field of view is and how accurate the depth perception. However, they offer bigger, bulkier binoculars, though they’re quite inexpensive because this construction is easy to manufacture.

Binoculars

Conversely, the Roof design means the prisms are very close to each other, so the objective and the eyepiece are in line with each other. That’s pretty hard to do, but you’ll be getting extremely clear and bright images, even if the retail price is more expensive.

Lens Coatings

We’ve talked about light passing through the lenses and what that means for the image brightness. But the lenses are made of glass, which happens to also reflect some amount of light, decreasing the proportion of light that gets through the lens.

To prevent that from happening, manufacturers use coatings. The simply coated lenses are covered with a layer of anti-reflective substance, but not entirely, while the fully coated lenses have one layer of coating on their whole surface. The same goes for multicoated lenses which feature multiple layers of coating, while the fully multicoated, which are the best, have multiple layers of coating throughout the lenses.

Binoculars Lens

Some coatings are better than others, though. For instance, an amber coating will also reduce the reflected light seeing as that’s one of its properties. So make sure to check which substance is used for the coating, along with how many layers of coating the manufacturer has applied.

Water and Weather Resistance

This is an important feature to account for, particularly if you’re using these binoculars in bad weather or if you’re boating. Waterproof binoculars mostly feature O-rings that keep water outside them, thus making them resistant to dust and debris too.

Waterproof Binoculars

Image credit: uplandoptics.com

If you read that a pair of binoculars is weather-resistant, that doesn’t make them completely waterproof. They can probably withstand a rain or two, but they’re not the best for boating when there’s the risk of you dropping them in water.

Fog Resistance

This feature isn’t included in the weather resistance specification because we’re talking about internal fog formation. If you’re moving the binoculars from a colder to a warmer temperature, the lenses could get foggy. That’s particularly irksome, but it’s also dangerous if water particles remain inside the binoculars.

Best compact binoculars

So that’s why some fog proof binoculars are nitrogen-purged or nitrogen-sealed to prevent internal fog formation. The air that would normally be inside the barrels is now replaced with nitrogen, which doesn’t condense. But there’s a difference between these two methods, though: the simple purging is not as effective as the full sealing.

Purpose

There are different sizes for binoculars, so you have to know what your magnification and the lens diameter are, as we explained above. The sizes and features above fits a different purpose, though, so let’s see which those are below.

Hiking and Outdoor Sports

These should be light and small, so you can carry them easily in your pocket or on a lanyard around your neck. That means they’re made from lighter and possibly not so durable materials, though they should be resistant to scratches and impacts.

Hiking Binoculars

In terms of the needed magnification, a 7 to 8x should be good enough for hiking and daily outdoor use. Choose a lens diameter of approximately 25 to 35 mm, which should give you enough light transmission during the day to see clear enough at a considerable distance.

Hunting

This definitely depends on the range you’re shooting at, but also on how big your game is. So you can definitely go with a smaller magnification of 4 to 5x for the short range for coyotes and other varmints. But if you’re hunting at a medium range, choose a 7x – 10x pair of binoculars, depending on how big your game is. The long-range demands a bigger magnification too, between 12x and 16x., but remember that the field of view decreases with the magnification.

Hunting Binoculars

It’s also important to pick the proper lens diameter. So you should go with a smaller one of 25 to 35 mm if you’re hunting during the day. However, it’s better to pick one bigger than 35 mm if you’re hunting at dusk or dawn or when it’s foggy.

Bird Watching

For this activity, you need to see good details at a considerable distance. That means choosing a magnification of 8 – 12x, depending on how far your bird is and how big it is. The usual magnification chosen for this type of binoculars is 8x, though.

The lens diameter that fits most types of bird watching is 42 mm, good enough for low light conditions as well as full sunshine. However, you can go even higher, at 50 mm or more if you’re after increased image brightness.

Bird Watching

Don’t forget to choose binoculars that have a longer eye relief here, you want them to be as comfortable as possible. You should also make sure the close focus feature works well since you’re probably want to zoom in often enough.

Boating

Because you’re out on the water, you don’t need a big magnification that’s bound to hurt your eyes. The usual magnification used is 7x, though 10x can also fit professional marine activities. You’ll also want a large diameter, between above 40 mm, at any rate, considering you want the best light transmission and image crispness.

Boating Binoculars

However, there are other similarly important features to consider for boating, like the overall build. A waterproof construction is essential seeing as there’s always the danger of dropping the binoculars in water. You should also get a pair that’s really resistant, so a rubber armor design could protect it from forceful impacts caused by shakes and turbulence.

Outdoor Concerts

At this point, you should be after a smaller magnification like 4x or 5x. This should give you a wide enough field of view to see the whole setup, as well as minute details of the performers’ faces and gestures. If you’re at an open-air theater, you might need a 7x, since now the focus is more on the actors.

Outdoor Concerts Binoculars

Depending on the available light, the lens diameter should be around 20 mm or so. If the concert is at night, with artificial light, you should probably choose a lens diameter closer to 30 mm, though.

Price vs. Quality

This is a pretty sore spot for most users, so it’s good to mention a few things about it. Most binoculars aren’t cheap, but that doesn’t mean that inexpensive binoculars work badly. Even if better materials and craftsmanship cost more, there are some decent designs which use quality materials too.

Binoculars

So your purpose is what should dictate who wins in the battle between price and quality. For instance, if you’re getting binoculars for constant use in inclement weather and for professional activities, you will probably have to invest a bit more than the average Joe.

Included Extras

Now, you’ll have to review everything else that comes in the package and how each item can be useful for you. We like to see things like cleaning cloths, carrying cases and lanyards for easy maintenance and for portability.

However, the cleaning cloth should be made from a material that doesn’t scratch the lenses, like microfiber, and the carrying case should be resistant to impacts. Needless to say, the lanyard should be resistant enough for prolonged use.

Included Extras

We also love stuff like tripod, head or helmet mounting which allow you more mobility or a better grip in situations when you can’t use both of your hands. So these are ideal for prolonged nature observation or for hunting. And don’t forget the warranties, which can be extremely helpful in case you need to repair or exchange your pair of binoculars for a new one.

Night Vision

If you’re getting a pair of binoculars for nighttime applications, you need to consider the generation you’re picking too, apart from the other specifications we’ve discussed above. So you first need to take into account the light gain, meaning how many times the light is amplified. With just a maximum of 900 times for Gen 1, Gen 2 can easily beat that with at least 20,000 times.

The system resolution is also better for Gen 2, which amplifies the light more, meaning the rendered images will be sharper. The sensor for Gen 2 binoculars is also more sensitive to light, so the resolution is better since it picks more light, from throughout the lens, including the periphery.

Night Vision Binoculars

The infrared LED is another feature to consider since it allows you to see good images in pitch black. Make sure you can see far enough with it, though, particularly if you’re into star gazing. And for night vision binoculars, the ability of you mounting them on your helmet becomes quite essential.

Final Thoughts

We’ve taken you through the most important features that influence your choice of a reliable pair of binoculars. We’ve tried to explain everything as simply as we could, so you can put these notions into practice and make an informed choice. We know it’s better to test out various binoculars with the same features and from different brands to pick something that fits, but we also know that’s not always possible.

So now tell us a bit more about yourself. What will you use these binoculars for? Do you already have a pair? What features do you think are more likely to influence your purchase? What have we missed in this article? Leave us a comment below!

ABOUT THE AUTHOR

Russell McCarty

Russell McCarty

Russell considers backpacking one of his great passions in life. He actually managed to transform his passion into a living becoming a professional adventurer. Russell loves long-distance backpacking and he enriched his portfolio with famous trails like the Alaska-Yukon Expedition or the Appalachian Trail. With thousands of miles under his feet, Russell is the expert to consult when it comes to how to prepare for a successful outdoor adventure.