If you’ve ever picked up a pair of binoculars, you’ve probably noticed a set of numbers printed on them. These numbers are the key to understanding the binoculars’ performance, and knowing what they mean will help you choose the perfect pair. Let’s break down exactly what are the numbers on binoculars and how they affect your view.
The most common numbers you’ll see look something like “8×42” or “10×50.” These two figures tell you the magnification power and the size of the objective lenses. The first number is always the magnification. For example, “8x” means the object will appear eight times closer than it would to your naked eye. The second number is the diameter of the objective lenses (the ones farthest from your eyes) in millimeters. Larger lenses gather more light, which is crucial for viewing in low-light conditions like dawn or dusk.
What Are The Numbers On Binoculars
This combination of magnification and lens size defines the core identity of any binocular. It’s the first spec you should look at. Understanding this simple code unlocks everything else about how the binoculars will perform in the real world.
Magnification Explained: The First Number
The magnification number tells you how much closer the subject will appear. An 8x binocular makes things look eight times closer, while a 10x makes them look ten times closer. Higher magnification isn’t always better, though.
Higher power (like 12x or more) can make the image shakier because it amplifies every tiny hand movement. They are also often heavier and have a narrower field of view. For general use like birdwatching or sports, 8x or 10x magnification is often the sweet spot. It provides a good balance of detail and stability.
Objective Lens Size: The Second Number
The second number, like “42” in 8×42, is the diameter of the front lenses in millimeters. This is critical for light gathering. Think of these lenses as light buckets—the bigger the bucket, the more light it collects.
More light means a brighter image, especially important in poor lighting. However, larger lenses also mean a larger, heavier binocular. Here’s a quick guide:
- 20-25mm (Compact): Great for pocketability and daytime events. Image dims quickly in low light.
- 30-40mm (General Purpose): Excellent all-around size for birding, hiking, and sports. Good balance of light and weight.
- 42mm+ (Low-Light Specialist): Ideal for dawn, dusk, or astronomy. Heavier but offer the brightest views.
Other Important Numbers and Specs
Beyond the main two numbers, you might see other figures that are just as important for choosing the right tool.
Field of View
This number, often in feet at 1000 yards or degrees, tells you how wide an area you can see. A wider field of view makes it easier to follow moving subjects like birds or athletes. Generally, lower magnification gives a wider field of view.
Exit Pupil
You can calculate this yourself: divide the objective lens size by the magnification. For 8×42 binoculars, 42 ÷ 8 = 5.25mm. This is the diameter of the beam of light that hits your eye. A larger exit pupil (over 4mm) gives a brighter image and is easier to look through, especialy if you wear glasses.
Close Focus
This is the minimum distance at which the binoculars can focus. If you enjoy watching butterflies or insects, a close focus of 6 feet or less is very usefull. Some general binoculars might only focus down to 15 or 20 feet.
Eye Relief
Measured in millimeters, this is the distance from the eyepiece lens to your eye where you can still see the full image. If you wear eyeglasses, you’ll need a longer eye relief (usually 15mm or more) to see the entire field of view without vignetting.
How to Choose the Right Numbers for You
Your ideal numbers depend entirely on what you plan to do. Here’s a simple step-by-step guide to match the numbers to your activity.
- Identify Your Main Use: Be honest about where you’ll use them most.
- Prioritize Stability vs. Detail: For handheld use, stick to 8x or 10x. Use a tripod for magnifications above 12x.
- Consider Light Conditions: If you’ll be out in early morning or evening, choose a larger second number (like 42 or 50).
- Factor in Portability: If you’ll be hiking long distances, a compact model (e.g., 8×25) might be worth the trade-off in brightness.
Here are some common activity recommendations:
- Birdwatching & Hiking: 8×42 is the classic, versatile choice.
- Marine & Safari: 7×50 or 8×50 for stability and superb low-light performance.
- Concerts & Sports (Daytime): 8×32 or even compact 8×25 are lightweight and easy to carry.
- Astronomy: 10×50 or higher, but be prepared to use a tripod for steady viewing.
Common Mistakes to Avoid
When looking at the numbers, its easy to get drawn to the biggest ones. Avoid these pitfalls:
- Overestimating Magnification: 12x binoculars are very hard to hold steady without support. The image shake can ruin the view.
- Ignoring Weight: That 10×50 model seems great until you’ve had it around your neck for three hours.
- Forgetting About Eye Relief: Glasses wearers must check this spec—it’s often overlooked in stores.
- Assuming Bigger is Always Brighter: Optical coating quality matters just as much as lens size for image brightness and clarity.
FAQ Section
What do the numbers 10×50 mean on binoculars?
The “10x” means 10x magnification. The “50” means the front objective lenses are 50mm in diameter. This is a configuration suited for low-light conditions but is relatively large and heavy.
Which is better, 8×42 or 10×42?
The 8×42 will give you a wider field of view, a brighter exit pupil, and less image shake. The 10×42 brings you 25% closer detail but is slightly shakier and has a narrower view. For most handheld use, 8×42 is often recommended.
What does the field of view number mean?
It describes the width of the area you can see through the binoculars at a specific distance, usually 1000 yards. A field of view of 340ft at 1000yds means you’ll see a 340-foot-wide slice of the landscape from left to right.
Are higher magnification binoculars better?
Not necessarily. While they show more detail, they amplify hand shake, have a narrower field of view, and are often heavier. For general use, moderate magnification like 8x or 10x is typically more effective and enjoyable.
What is a good exit pupil size?
For daytime use, 3-4mm is adequate. For low-light conditions, aim for 5mm or larger. A larger exit pupil also makes it easier to find and maintain the image, which is helpfull for beginners.
Putting It All Together
Now you know that the numbers on binoculars are a precise code describing there capabilitys. The magnification and objective lens size are the starting point, but don’t forget to check the field of view, eye relief, and close focus based on your personal needs. The best binoculars are the ones that feel comfortable and give you a clear, steady view of the things you love to watch. With this knowledge, you can confidently decode the specs and select a pair that will serve you well for years to come.