If you’ve ever looked at a pair of binoculars, you’ve seen a set of numbers printed on them. Understanding what do numbers mean on binoculars is the first step to choosing the right pair for your needs. These figures aren’t just model codes; they tell you exactly how the binoculars will perform in the field, from watching birds in your backyard to observing stars at night.
What Do Numbers Mean On Binoculars
The most common numbers you’ll see look something like “8×42” or “10×50.” This combination is the binocular’s magnification and objective lens size. It’s the core specification that defines its capability. Let’s break down what each part means so you can make an informed decision.
The First Number: Magnification Power
The number before the “x” is the magnification. For example, in 8×42, the “8” means the object will appear eight times closer than it would with your naked eye. If you’re looking at a bird 80 feet away, it will seem like it’s only 10 feet away.
- Higher Magnification (e.g., 10x, 12x): Brings subjects much closer. Good for long-distance viewing like astronomy or open-field wildlife.
- Lower Magnification (e.g., 7x, 8x): Offers a wider field of view and a brighter image. They are also easier to hold steady. Ideal for general use, birding in woods, or sports events.
A common mistake is thinking bigger is always better. High magnification also amplifies hand shake, making the image jittery without a tripod.
The Second Number: Objective Lens Diameter
The number after the “x” is the diameter of the front lenses in millimeters. In 8×42, the “42” means each front lens is 42mm across. This is crucial because it determines how much light the binoculars can gather.
- Larger Objective Lens (e.g., 42mm, 50mm): Captures more light, resulting in a brighter image, especially in low-light conditions like dawn, dusk, or indoors. They are, however, heavier and bulkier.
- Smaller Objective Lens (e.g., 25mm, 32mm): Makes for a more compact, lightweight pair that’s easy to carry. Image brightness can be excellent in full daylight but diminishes faster as light fades.
Putting It All Together: 8×42 vs. 10×50
Let’s compare two popular configurations to see how the numbers play out in practice.
8×42 Binoculars: This is arguably the most versatile all-around choice. The 8x power provides good detail with a stable view, and the 42mm lens offers a bright image for most daytime activities. They are a perfect balance of performance, size, and weight.
10×50 Binoculars: These pull subjects closer and gather even more light than an 8×42. They excel for viewing over vast distances or in poorer light. The trade-off is a narrower field of view, more noticeable hand shake, and increased weight. They are often preferred for hunting or astronomy.
Other Important Numbers and Specs
While magnification and lens size are the headliners, other numbers on the binoculars body are also important.
Field of View
This number, often listed in feet at 1000 yards or degrees, tells you how wide an area you can see. A wider field of view (e.g., 393 ft) makes it easier to follow moving subjects like birds or athletes. Generally, lower magnification offers a wider field of view.
Exit Pupil
You can calculate this yourself. Divide the objective lens diameter by the magnification. For 8×42 binoculars, 42 ÷ 8 = 5.25. The exit pupil is 5.25mm. This is the diameter of the light beam that reaches your eye. A larger exit pupil (over 4mm) means a brighter image and easier eye placement, which is great for low-light use.
Close Focus
This is the minimum distance at which the binoculars can focus. If you enjoy looking at butterflies or insects, you’ll want a close focus distance of under 10 feet. Some models can focus as close as 4 or 5 feet.
Eye Relief
Measured in millimeters, eye relief is the distance from the eyepiece lens to your eye where you can still see the full image. If you wear glasses, you typically need an eye relief of 15mm or more to see the entire field of view comfortably. This spec is critical for eyeglass wearers.
How to Choose the Right Numbers for You
Your ideal binocular depends on what you plan to use them for. Here’s a simple guide:
- General Purpose & Birding: 8×42 is the gold standard. Excellent light, good field of view, stable image.
- Wildlife & Hunting: 10×42 offers more reach while keeping a relatively manageable size. For low-light dawn/dusk, consider 10×50.
- Astronomy: Go for high light gathering: 10×50 or 12×50. A tripod adapter is highly recommended for magnifications over 10x.
- Sports & Concerts: A wider field of view is key. 7×35 or 8×32 are great choices for following fast action.
- Backpacking & Hiking: Prioritize weight and size. Compact models like 8×25 or 10×28 are perfect, even if they sacrifice some low-light performance.
Remember, the best way to choose is to try different models if you can. See how they feel in your hands and how the view looks to your eyes.
Common Mistakes to Avoid
- Over-magnifying: Choosing 12x or 16x for handheld use often leads to disappointing, shaky images.
- Ignoring Weight: Those large 10×50 binoculars might seem great in the store, but they can feel very heavy after an hour of hiking.
- Forgetting Eye Relief: Glass wearers who overlook this spec will struggle to see the full picture.
- Assuming Bigger Lenses Are Always Better: For bright sunny days, a 32mm lens can be perfectly sufficient and much easier to carry.
FAQ: Your Questions Answered
What does 10×50 mean on binoculars?
It means the binoculars have 10x magnification and 50mm diameter objective lenses. They make objects appear 10 times closer and are very good for low-light conditions due to their large light-gathering lenses.
Are higher magnification binoculars better?
Not necessarily. While they bring things closer, they also have a narrower field of view, are harder to hold steady, and are often heavier. The best magnification depends on your specific use.
What is the best all-around binocular size?
For most people, an 8×42 binocular offers the best balance of magnification, image brightness, field of view, and portability. It’s a highly recommended starting point.
What do the numbers on binoculars mean for eye relief?
Eye relief is a separate number, usually listed in the specs. It’s the distance your eye can be from the eyepiece and still see the whole image. Look for 15mm or more if you wear eyeglasses.
Is a 10×42 or 8×42 better for bird watching?
Many birders prefer 8×42 for its wider field of view (easier to find birds in foliage) and steadier image. 10×42 is better for open areas like shorelines or wetlands where you need more detail at greater distances.
Now you know that the numbers on binoculars are a straightforward guide to their performance. By understanding magnification, lens size, and a few other key specs, you can confidently select the perfect pair that fits your adventures. No matter if your watching a rare eagle or your child’s soccer game, the right numbers make all the difference.