If you’re new to birdwatching, hunting, or long-range target shooting, you might wonder how are spotting scopes rated. Understanding these ratings is key to choosing the right tool for your needs, as they tell you exactly what a scope can do.
Spotting scopes are primarily rated by their magnification power and objective lens size, shown as two numbers like 20-60×80. But there’s more to the story. We’ll break down all the specifications so you can shop with confidence and get the best scope for your activities.
How Are Spotting Scopes Rated
The main rating for any spotting scope is its model number, which looks like “15-45×60” or “20-60×80.” This isn’t just a random code. It’s the most important piece of information, telling you the scope’s magnification range and its light-gathering ability.
The Magnification Number (The First Part)
The first number, or set of numbers, refers to magnification. A scope with “20-60x” means it offers variable power. You can zoom from 20 times closer (20x) all the way up to 60 times closer (60x) than what your naked eye sees.
- Fixed vs. Variable: Some scopes have a single number (like 30x), meaning fixed magnification. Most modern scopes are variable, offering flexibility.
- Higher Isn’t Always Better: At very high magnification (like 60x), the image can become shaky without a tripod and may appear dimmer or fuzzy if the objective lens is too small.
The Objective Lens Diameter (The Second Part)
The second number, after the “x,” is the diameter of the front (objective) lens in millimeters. In a “20-60×80” scope, the objective lens is 80mm wide. This is crucial for performance.
- Light Gathering: A larger lens (e.g., 80mm) captures more light than a smaller one (e.g., 60mm). This means a brighter, clearer image, especially in low-light conditions at dawn or dusk.
- Trade-off: Bigger lenses mean a heavier, bulkier scope. A 60mm scope is more portable, while an 80mm or 90mm scope is better for stationary, critical viewing.
Lens Quality and Coatings
Spec sheets also rate the optical quality through coating descriptions. These are vital for image clarity, color accuracy, and brightness.
- Coated: A single layer on some lens surfaces.
- Fully Coated: A single layer on all air-to-glass surfaces. This is a good minimum standard.
- Multi-Coated: Multiple layers on some lens surfaces. Improves light transmission significantly.
- Fully Multi-Coated: Multiple layers on all air-to-glass surfaces. This is the premium rating you want for the best image.
Glass quality matters too. Scopes with Extra-low Dispersion (ED) or Fluorite glass reduce chromatic aberration (color fringing), providing sharper, high-contrast images.
Field of View
This rating, usually in feet at 1000 yards or degrees, tells you how wide an area you can see through the scope at a specific magnification. A wider field of view makes it easier to locate and follow moving objects, like birds.
- It decreases as magnification increases.
- Wider is generally better for scanning and tracking.
Close Focus Distance
This is the minimum distance at which the scope can focus on a subject. A shorter close-focus distance (e.g., 10 feet) is excellent for butterfly watching or studying details on closer objects, while scopes for long-range shooting might have a longer close focus.
Eye Relief
Eye relief is the distance your eye can be from the eyepiece and still see the full image. It’s critical for eyeglass wearers.
- Long eye relief (15mm or more) allows you to see the full view with glasses on.
- Short eye relief means you must press your eye right up to the cup, which is difficult with glasses.
Waterproof and Fogproof Construction
Most quality scopes are rated as waterproof and nitrogen or argon purged to be fogproof. This isn’t about depth, but about sealing out moisture and preventing internal fogging due to temperature changes. Look for O-ring seals and a solid warranty.
How to Use These Ratings When Choosing a Scope
Now that you know how scopes are rated, how do you apply it? Match the ratings to your primary activity.
For Birdwatching and Wildlife Observation
- Magnification: A versatile 15-45x or 20-60x range is ideal.
- Objective Lens: 60mm to 80mm for a good balance of light and portability.
- Optics: Prioritize Fully Multi-Coated lenses and ED glass.
- Close Focus: Should be relatively short (under 20 feet).
For Hunting (Spotting Game)
- Magnification: 15-45x or 20-60x is common. You’ll often use mid-range powers for scanning.
- Objective Lens: Consider weight. A 65mm or 80mm ED scope is excellent for backpacking if you need high performance.
- Durability: Rugged, waterproof construction is non-negotiable.
For Target Shooting and Digiscoping
- Magnification: Higher magnifications (up to 60x or 80x) are used to see small bullet holes at long distances.
- Objective Lens: Larger is better (80mm-100mm) for maximum resolution and clarity at high power.
- Digiscoping: Look for a scope with a dedicated camera adapter and a long, consistent eye relief.
Common Mistakes to Avoid
When looking at ratings, a few pitfalls can lead you to the wrong choice.
- Chasing Maximum Magnification: Ignoring the objective lens size. A 60x scope with a 50mm lens will give a dim, poor-quality image at full zoom.
- Overlooking Eye Relief: If you wear glasses, always check this spec. Don’t assume it will work for you.
- Ignoring the Tripod: Any magnification over 30x really requires a steady tripod. A shaky image makes a high-rated scope useless. Factor a good tripod into your budget.
- Forgetting About Portability: That high-end 100mm scope is amazing, but are you willing to carry its weight up a mountain?
FAQ: Spotting Scope Ratings Explained
What does 20-60×80 mean on a spotting scope?
It means the scope has a variable magnification from 20 power to 60 power, and it has an 80mm diameter objective lens. The first numbers are the zoom range, the last number is the lens size.
Is a bigger objective lens always better?
It provides a brighter image and better performance in low light, but it also makes the scope heavier, larger, and often more expensive. Choose based on your need for light-gathering versus portability.
What is the best all-around spotting scope magnification?
A zoom range like 15-45x or 20-60x paired with a 60mm to 80mm objective lens is considered the most versatile for general use, from birding to hunting.
Why does the image get darker when I zoom in?
The exit pupil (the beam of light hitting your eye) gets smaller as magnification increases. A larger objective lens helps compensate for this, which is why the two ratings are balanced in the model number.
Are expensive spotting scopes worth it?
For casual use, a mid-range scope is fine. For serious viewing, especially in challenging light, the investment in premium coatings (Fully Multi-Coated) and ED glass provides a noticeably sharper, brighter, and more color-true image that’s easier on your eyes over long periods.
Understanding how are spotting scopes rated takes the guesswork out of shopping. By focusing on the key numbers—the magnification, the objective lens size, and the quality of the coatings—you can cut through the marketing and select a scope that truly fits how you plan to use it. Remember to balance the specs with practical needs like weight and eye relief, and you’ll be ready to enjoy crystal-clear views of the distant world.