Last Updated on January 11, 2021
Since the invention of the telescope in the 17th century, soldiers, sailors, and scientists have been inspired to put two spyglasses side-by-side to enjoy binocular vision. And while several technological advancements have been made since this time, many of the same professions and hobbies call on trusty binoculars for their work.
No matter whether you’re looking for a pair of binoculars for bird-watching, concert-going, or to gaze on the stars in the night sky, equipping yourself with knowledge and information will help you choose the best pair at the best price. Follow along as we explore the design and features of binoculars, discussing which types are best for which activities and what to look for when buying binoculars.
What to Look for in Binoculars
While each pair of binoculars is usually designed for a specific application, they are all built on a similar foundation of optical parameters and physical features.
Six optical parameters are adjusted in a fine balance to produce a wide variety of binocular applications. They are:
- Magnification, the first number given in a binocular description, describes how many times greater the size of the object in view is increased. For example, an 8x42 pair of binoculars would allow the viewer to see any object at 8 times the size of the original seen from that distance.
- Objective Diameter, the second number in a binocular description (e.g. 8x42), determines the resolution or sharpness of the final image. Generally, a larger objective diameter will produce a sharper image and be more useful for objects much further away.
- Field of View is related to the magnifying power and is inversely proportional to it. The greater the magnification, the smaller the total field of view that can be included in a single glance.
- Exit Pupil is calculated by dividing the objective diameter by the magnification and determines how well the human eye can see in a given light condition. Since the average human pupil operates best between 3mm and 8mm, many exit pupil diameters will fall in this range. In the example above, 42 divided by 8 will equal a 5.25mm exit pupil.
- Eye Relief describes how far away the viewer’s eyes must be from the rear end of the binoculars to see a clear and undistorted image. If you’ve ever found it difficult to use binoculars while wearing your eyeglasses, a larger eye relief can solve this problem.
- Close Focus Distance, just like it sounds, is the closest point that the binoculars can focus on and is largely a product of the specific optical design of a given pair of binoculars.
Features and Mechanical Design
Optics may steal the show in the world of binoculars, but certain mechanical functions and accessory features can turn a good pair of binoculars into a great one. Some of the most important features are:
- Porro Prism vs Roof Prism Design may be the most important physical distinction to make, as it will greatly affect the overall durability and image resolution of the binoculars. Roof prism binoculars have the edge in overall durability and waterproofing, but Porro prism lenses boast greater image quality and depth of focus.
- Image Stabilization is one of the most recent mechanical features to be added to high-end binoculars and is achieved via the integration of a gyroscope or internal vibration dampener. Though it cannot produce an image of the same quality as you’d find when using a tripod, this feature can make binoculars more accessible to people with chronic hand tremors.
- Parallel Alignment of the binoculars’ lenses allows them to produce a single image and can cause serious image distortion and headaches when disturbed. Internal support cells or external set screws allow for adjustments to alignment, though it’s often best to leave this delicate task to a professional.
- Optical Coatings allow for increasing specialization in general binocular categories. The most common types include anti-reflective coatings that increase image contrast and phase correction coatings that sharpen resolution.
The focusing arrangement of a pair of binoculars changes the distance between the lenses nearest you, known as the ocular lenses, and those farthest away, the objective lenses. The focus type can be broken into three main categories:
- Independent Focus allows for adjustments to a single eyepiece and has traditionally been favored for military applications.
- Central Focusing controls both lenses through a center-mounted wheel, allowing for quick refocusing without eyepiece readjustment.
- Focus-Free or Fixed Focus binoculars do away with focusing controls entirely and are set to a single range and magnification. They are often cheap and convenient but lack the image quality and subtlety prized by hobbyists.
When Do You Need to Use a Tripod with Binoculars?
Often relegated to use with high-powered telescopes or specialty camera lenses, tripods can also combine wonderfully with binoculars in a variety of hobbies or sporting interests.
While it’s rarely required to use a tripod for image stabilization, even an inexpensive pair of binoculars can be brought into a much clearer focus by mounting them on a tripod and reducing imperceptible shaking movements. If you’ve ever entertained the idea of using binoculars for hunting, bird watching, or astronomy purposes, a tripod can be a useful addition to your bag of tricks that extends the useful range of any pair of binoculars.
Pros & Cons of Using a Tripod with Binoculars
- Increases effective range of any pair of binoculars
- Sharpens image contrast and clarity
- Very useful for long-range spotting, including astronomy
- Added expense
- Increased weight can be inconvenient for spontaneous activities
- Requires precise dialing in and is not suitable for quick-moving activities
Uses for Binoculars
There are countless brand names and models to choose from, so it’s hard to know exactly how to buy binoculars. Newly armed with your background knowledge of binocular specifics, let’s take a closer look at which binoculars might be best for the most popular binocular-centric activities:
A broad category of potential activities and sights like hiking requires an equally versatile pair of binoculars to match. Choosing a portable, rugged pair of binoculars in the general area of 8×40 will give you the potential for scoping out new trails and observing wildlife, while a 10x magnification can let you get up close and personal with the sights from a mountaintop. But don’t forget to account for the actual weight of the binos.
Once you know how to buy binoculars for birding, the options are nearly endless. Like hiking binoculars, a perfect pair of handheld lenses for birding will need to be equal parts portable and versatile. Magnifications of 8x and 10x are most common, but 7x binoculars can allow for a wider field of vision that’s conducive to spotting more elusive birds. Because bird watching involves a lot of holding still in a single position, it’s wise to choose a pair of binoculars that’s lightweight and easy for you to handle.
Depending on what sort of game you may be hunting, magnifications from 8x to 10x will let you see your targets clearly while maintaining adequate distance for rifle setup. Given the often-stationary nature of hunting, a tripod may be your best investment to go alongside a simple pair of 8×40 binoculars.
Image credit: Fort Carson, Flickr
Sporting Events and Concerts
Choosing a pair of binoculars for sporting events and concerts is a matter of balancing width and depth in your field of vision. For long-distance sporting events, we’re big fans of 8×42 binoculars, while the less common 5×35 or 7×35 models may work better for mid-range viewing.
Seafaring folks require a wide field of vision to make the best use of a pair of binoculars, making 7x the preferred magnification of most sailors. The classic size for marine binoculars is 7×50, a perfect ratio to minimize the negative effects of the inevitable shaking and movement that occur while viewing from a sailing vessel.
Image credit: Jon Sosner
While telescopes will always reign supreme for serious astronomical observations, there are a surprising amount of astronomy-specific options out there for binoculars. They’ll feature massive magnification ranges, with 15×70, 20×80, or even 25×100 catering specifically to skywatchers.
How Much Do Binoculars Cost?
Available in an exceptionally wide range of designs, magnification powers, and intended purposes, a good pair of binoculars can cost anywhere from $100 to $500. General purpose, Porro prism binoculars will make up the low end of this range, while roof prism binoculars and ultra-powerful astronomy models will carry the highest price tags.
Final Thoughts on Choosing a Pair of Binoculars You’ll Love
Finding the right pair of binoculars for a single activity is challenging enough — and deciding on a single pair that’s perfect for your hobbies and activities is likely to require considerable testing and comparisons. When in doubt, start with the most common magnifications (such as 8×42), and test them side-by-side with less common magnifications to get a feel for your specific preferences. Once you find the pair that suits your eyes to a T, all of your time and efforts will be well worth the results.