If you’re new to buying binoculars, you might wonder how are binoculars rated. Understanding these ratings is the key to picking the perfect pair for your needs. The numbers and terms can seem confusing at first, but they simply describe the binoculars’ power and capabilities. This guide will explain everything in plain language.
You’ll learn what the specs mean and how to use them to make a smart choice. Let’s clear up the mystery so you can shop with confidence.
How Are Binoculars Rated
The most basic rating you’ll see is a pair of numbers, like 8×42 or 10×50. This is the binocular’s model number, and it tells you its two most important features. The first number is the magnification. The second number is the diameter of the objective lens in millimeters.
For example, in 8×42 binoculars, the “8x” means objects appear eight times closer than they do with your naked eye. The “42” means the front lenses are 42mm wide. This combination dictates much of the binocular’s performance.
Breaking Down Magnification (The First Number)
Magnification tells you how much closer the view will be. Higher isn’t always better, though. Here’s what you need to consider:
- Stability: Higher magnification (like 12x or more) amplifies hand shake. You’ll likely need a tripod for a steady veiw.
- Field of View: Higher power usually means a narrower field of view. This makes it harder to locate fast-moving birds or follow sports action.
- General Use: For most handheld activities like birdwatching, hiking, or sports, 7x to 10x magnification is the sweet spot. 8x is perhaps the most popular all-around choice.
Understanding Objective Lens Size (The Second Number)
This number is the diameter of the lenses at the front of the binoculars. It’s crucial because it determines how much light can enter. More light means a brighter image, especially in low-light conditions at dawn or dusk.
- Small (20-30mm): Compact and lightweight, but image brightness suffers in poor light. Great for daytime concerts or hiking where size matters.
- Medium (32-42mm): The best balance for most users. Offers good brightness and a relatively compact size. An 8×42 is a classic recommendation.
- Large (50mm+): Excellent for low-light viewing like astronomy or wildlife at twilight. They are heavier and bulkier, however.
Key Performance Specifications Explained
Beyond the main two numbers, other ratings describe the quality of the view.
Field of View
This is the width of the area you can see, usually measured in feet at 1000 yards. A wider field of view is helpful for tracking animals or scanning landscapes. Lower magnification typically gives a wider field.
Exit Pupil
You can calculate this yourself: divide the objective lens size by the magnification. For 8×42 binoculars, the exit pupil is 5.25mm (42 ÷ 8). This number should match your eye’s pupil in low light (up to about 7mm for young adults). A larger exit pupil (over 4mm) gives a brighter, more comfortable viewing experience, especially if you wear glasses.
Eye Relief
This is the distance from the eyepiece lens to your eye where you can still see the full image. It’s critical for eyeglass wearers. Look for a rating of 15mm or more if you wear glasses. Shorter eye relief means you have to press your eyes closer, which is difficult with glasses on.
Close Focus
This is the minimum distance at which the binoculars can focus. If you enjoy looking at butterflies, insects, or flowers, a close focus of 6 feet or less is a valuable feature. Some general-purpose binoculars only focus down to 15 or 20 feet.
Optical Coatings and Build Quality
Ratings aren’t just about numbers. The quality of the lenses and prisms inside is vital. Look for these terms:
- Coated: Some lenses have anti-reflective coatings.
- Fully Coated: All air-to-glass surfaces have a single layer coating. This is a basic standard.
- Multi-Coated: At least one lens surface has multiple layers of coating, improving light transmission.
- Fully Multi-Coated: The gold standard. Every air-to-glass surface has multiple layers. This gives the brightest, clearest, highest-contrast image.
Also, check for the prism type. Roof prisms make for slimmer binoculars but are often more expensive. Porro prisms are chunkier but can offer excellent value and depth perception.
Putting It All Together: Choosing Your Binoculars
Now, let’s apply these ratings to real-world choices. Follow these steps to narrow down your options.
- Define Your Primary Use: Is it birdwatching, hunting, astronomy, sports, or general travel?
- Pick a Magnification: For handheld versatility, choose 8x or 10x. For stationary or tripod use, consider 12x or higher.
- Select Lens Size: Match it to your light conditions. Choose 42mm for a great all-round balance, or 50mm+ for low light.
- Check Eye Relief: If you wear glasses, ensure it’s 15mm or longer.
- Set a Budget: More money generally buys better coatings, waterproofing, and durable construction. Don’t overlook used markets for quality optics.
- Try Before You Buy: If possible, look through different models. Check for a sharp, bright image and comfortable feel in your hands.
Common Mistakes to Avoid
When learning how are binoculars rated, it’s easy to focus on the wrong thing. Here are a few pitfalls.
- Over-Prioritizing Magnification: A shaky, narrow 16x image is often worse than a steady, wide 8x one.
- Ignoring Weight: Bigger lenses are heavier. If you’ll be carrying them for hours, a compact 8×32 might be more enjoyable than a full-size 10×50.
- Assuming Waterproofing: Not all binoculars are waterproof. If you’ll be in damp environments, look for “waterproof” or “nitrogen-purged” specs, not just “weather resistant.”
- Forgetting About the Case: A good case and strap are part of the package. They make carrying and protecting your investment much easier.
FAQ Section
What do the numbers on binoculars mean?
The numbers (e.g., 10×42) indicate magnification power and objective lens diameter. The first number is how many times closer objects appear, and the second is the size of the front lenses in millimeters, which affects light gathering.
What is the best binocular rating for bird watching?
Most birders prefer 8×42 binoculars. They offer a good balance of magnification for detail, a wide field of view for tracking birds, and a large enough lens for decent brightness in forests or at dawn.
How is binocular strength measured?
“Strength” usually refers to magnification, which is the first number in the rating (the “x” number). It’s a linear measurement, so a 10x binocular makes an object appear ten times closer than it would to the unaided eye.
Are higher rated binoculars always better?
Not necessarily. Higher magnification can make the image shakier and the field of view narrower. The best rating is the one that suits your specific activity, physical ability (to hold them steady), and budget. Optical quality often matters more than just the numbers.
In conclusion, understanding how binoculars are rated empowers you to look past marketing and see what really counts. Remember the core numbers, pay attention to eye relief if you wear glasses, and always opt for the best optical coatings you can afford. With this knowledge, you’re ready to find a pair that will bring the world closer for years to come. The perfect match is out there for every adventure.