Binoculars shopping can be confusing with so many numbers and specs to understand. And the price differences between one pair and another can be staggering. When asking yourself “what do the numbers on binoculars mean?” the manufacturer’s information isn’t always clear.We’ll take a look at what it all means in this binocular buying guide so you understand binocular numbers, pick the best magnification for binoculars that’ll fit your use, and know exactly why you are spending more for benefits that will actually make a difference in your viewing. Once you understand binocular specs, you can read those binocular reviews and tell the difference between high-end binoculars and cheap ones. That way if you decide to shell out your hard-earned cash, you’ll be confident you’re getting your money’s worth. If you want some great options you can read our article: Best Binoculars for Outdoor Adventures. For the skinny on how to shop for binoculars, read on.Photo by Pawel Janiak on Unsplash
Magnification:
The first number in a binocular description on the packaging is magnification. Generally, the best magnification for binocular is either an 8 or 10 magnification. If the package says 8 x 30, then the object you are viewing looks eight times closer than with the naked eye. If it’s 10 x 25, then its ten times closer.As magnification goes up, the steadiness of the image goes down. A magnification of 10 is about the highest a human hand can hold without the image jumping around too much to see clearly, and anything higher than 10 will require a tripod. Anything lower does not bring the image close enough to warrant the weight of the binoculars around your neck.
TL:DR Choose either 8x or 10x binocular numbers on magnification for the outdoors
Objective lens:
The second number in our 8 x 40 designation indicates the size in mm of the objective lens (the one farther from your eye). This determines how much light gets into the lenses, so it has a lot to do with the amount of detail you can see. The higher the objective lens number, the bright and sharper your image. An 8 x 32 pair of binoculars will cost less and have less detail than an 8 x 40 pair. The trade-off here is weight. The bigger the objective lens, the larger the binoculars, and therefore, the more weight you are hefting around as you hike.TL:DR Choose between 30 and 45 objective lens for clear viewing without killer weight
The exit pupil is the second number divided by the first. The larger the exit pupil, the more steady the image you are viewing will be. For example, a pair of 8 x 40 binoculars has an exit pupil of 5. A pair of 10 x 30 binoculars has an exit pupil of 3.
What you can expect from your exit pupil binocular specs:
2-3 exit pupil is a fine choice for day viewing
4-5 exit pupil is good for dawn and dusk viewing
5-6 exit pupil is good for astronomy use
7+ exit pupil is ideal for marine (moving deck)
Prism:
There are two kinds of prisms, roof prisms and Porro prisms. Roof prisms are the newer kind. The tubes of the binoculars are straight from eye piece to objective lens. Porro prisms are the older design and are angled, which means the eye piece is narrower and the shaft widens to the objective lens. It’s hard these days to find Porro prisms, so we don’t need to discuss this too much.TL:DR Go with roof prisms
This is perhaps the most important aspect for your purchase, and weighs most heavily in the cost difference. Time to sit up and pay attention. There are three basic coatings.
Fully-coated binoculars mean that every lens has a single coat of anti-reflective coating to allow more light through the leans. Less light is lost as it bounces from one lens to another.
Multi-coatedbinoculars mean that some of the lenses have more than one coat making them slightly better than simple “fully-coated”.
Fully multi-coatedbinoculars mean both sides of every lens are coated with more than one layer. This is the pinnacle of the lens coating pyramid, and you will pay a premium for fully multi-coated. You will also get more light through the binoculars, so for activities like bird watching where the objects are small, fast-moving, and colors matter, it‘s worth the cost.
TL:DR Go with fully multi-coated if you can afford it
Final thoughts
There is a world of detailed knowledge out there if you want to dig deeper into binocular specs and uses, but this overview should make you well-armed to judge where to spend and where to save as you shop, depending on what you are going to use the binoculars for, and how much each feature brings you in terms of benefits vs. cost. Happy shopping!
Cecily has been camping and backpacking for more than 40 years. Her trips range from a quick overnight adventure in the woods to living out of her tent for months on end. Cecily’s knowledge and experience, gained from solo excursions as well as family camping with her 5 kids, can help you find the best camping gear for your needs.
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