Binoculars By the Numbers
Binoculars are typically advertised with two different numbers (e.g. 10x50). The first number is the level of magnification, and the second number is the aperture. Anything that offers more than 10x magnification is very difficult to use without a tripod. Higher magnification also magnifies the natural tremors in your hands.
The second number is the diameter of the objective lenses of binoculars or the front lenses. The diameter of the lens determines the light gathering ability of the binocular, with the greater light gathering ability of a larger lens translating into greater detail and image clarity. This is especially useful in low light conditions and at night.
Doubling the size of the objective lenses quadruples the light gathering ability of the binocular. For instance, a 7x50 binocular has almost twice the light gathering ability of a 7x35 binocular and four times the light gathering ability of a 7x25 binocular. This translates to a brighter, more detailed image.
Our Favourite Birding Binocular Sizes
Binoculars are also great for birding and wildlife viewing. Our favorite format for birding and terrestrial viewing is 8x42. They give bright views and a nice wide field of view. They’re also versatile enough to use for astronomy.
If you’re looking for something suitable for beginners, kids, or anyone with more of a tremble in their hand, we love anything in the range of 6x30. This size offers a wider field of view that makes it easier to locate and follow the bird you’re watching. They also reduce any shake in the image.
Other Things to Look for in Binoculars
Compactness and Ruggedness
Compactness and ruggedness are two major features to consider when looking for a pair of binoculars. Compactness relates to whether roof, porro, or other prisms are used in the binoculars, which affect the weight and size of the binoculars. Water resistance, waterproofing, and rubber armour designs make the binoculars more durable to withstand the rigours of portable, outside use in all kind of weather.
Binoculars rely on pairs of prisms to fold and erect the image in each tube assembly (binocular half). Doubled roof prisms are small and light enough that a pair of binoculars designed around them can have short, straight, and lightweight tubes. Thus, they are very compact and are the better choice when weight and size are key considerations.
Porro prisms and other types of prisms are bulkier and, when paired, result in a tube design that bends out at a side angle. Porro prism binoculars have the classic bulged tube designs and are larger than roof prism pairs.
Weather-resistant binoculars have minimal openings that can allow water to enter the optics. Waterproof binoculars go further and are designed to totally exclude water. They also may be nitrogen purged--filled with dry, inert gas--as an additional barrier to internal moisture, rendering them fogproof as well.
Rubber armoring provides a final level of external ruggedness and helps protect your binoculars from abrasion, damage, or loss of collimation (alignment) if accidentally dropped. The rubber also makes them easier to grip in damp or wet weather conditions.
Exit PupilThe exit pupil is the width of the beam of light leaving the eyepiece, usually measured in millimeters (mm). The larger the exit pupil, the brighter the image will be under low-light conditions. Exit pupil size is calculated by dividing the objective lens size by the magnification power. For example: You want to know the exit pupil of an 8x42 binocular. 42mm / 8 = 5.25mm. The exit pupil of our Sport Optics should correspond with the amount of dilation of your eye's pupil after it is fully dark-adapted. This number will be between 5mm and 7mm (the maximum amount for the human eye).
- For daytime viewing, a large exit pupil is not necessary but that does not mean that a binocular cannot be used for daytime viewing if it has a large exit pupil.
- For night viewing, a binocular with a 5mm or larger exit pupil will provide the maximum amount of light to the eye.
Eye relief is the distance in mm between your eye and the binocular/ spotting scope eyepiece that allows the full field of view to be comfortably observed. It measures the spacing from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the image is formed. Your eye should be positioned here to see the full field of view of the eyepiece.
Eye relief should be at least 10mm; 15mm will provide the best comfort, and you may need more if you wear eyeglasses.
Put your eye so it's just behind the eyepiece to take advantage of its eye relief. You’ll lose field of view if you place your eye farther away and may even move your eye out of the beam of light from the eyepiece. Getting too close will prevent you from blinking and may also cause a black ring to appear around the field of view.
These are great for young kids just learning how to use and handle optics. They will deliver a good, magnified view of what you’re looking for, and you won’t cry when they get dropped. My seven year old has been stress testing these and they’ve been a great tool for teaching him how to find and focus on birds. It’s also been a great way to teach him about caring for optics.
These are great for responsible kids, and adults who want a nice wide field of view. Light in the hand, with a nice bright view thanks to a 5mm exit pupil, these will provide satisfying views of birds in most light conditions. The extra field of view that comes with the lower magnification is particularly nice for fast moving targets, or for new birders learning how to find the bird they want a closer look at.
Best Binoculars Under $300
These Pentax binoculars are a great performer. They deliver nice views, and great value. We really like them because of how sturdy they are, they’re a genuinely nice option for beginners, and a hidden value in the world of Japanese optics.
Best Binoculars Under $600
These Kowa’s are quite special. They’re built incredibly well and outperform much more expensive binoculars. The fit and finish is excellent and this price point and so are the views. You get nice, close focus, and good field of view and depth.
Best Binoculars Under $1200
Zeiss has an incredible heritage, and there’s something (maybe snobbery) about a pair of good German engineered binoculars. These offer incredible, accurate color and a nice feel in hand. The also offer a nice close focus and a good field of view.
Best Binoculars at Any Price
If you’re looking for the absolute best, you’re going to wind up with a lot of different opinions. In our view, the Leica Noctovids are extraordinary binoculars. They are solid, lightweight, with a wide field of view and a large sweet spot for viewing. We don’t think there’s a better pair of binoculars available at any price.
Binoculars are a great tool to have. They're easy to carry around with you and to travel with. They can be an incredible instrument for astronomy, and they're the best equipment for birding.
There are a lot of factors to consider when choosing a pair of binoculars. We have a great selection of the best binoculars from Leica, Pentax, Celestron and more that will help you with birding, astronomy and anything else. If you have any questions, we're here to help you make the right choice.