If you’re looking at binoculars, you’ve probably seen numbers like 10×50. But what does the 10×50 mean on binoculars? These two numbers are the most important specs to understand, as they tell you exactly how the binoculars will perform. Getting to know them is the first step to choosing the right pair for your needs.
In simple terms, the numbers describe the magnification and the size of the front lenses. The first number is the power, and the second is the diameter. This combination determines how close things appear, how bright the image is, and even how steady your view will be. Let’s break it down so you can shop with confidence.
What Does The 10×50 Mean On Binoculars
The marking “10×50” is the binocular’s model number or specification. It’s a universal code. The “10x” refers to the magnification power. It means the object you are viewing will appear ten times closer than it would with your naked eye. The “50” is the diameter of the objective lenses (the front lenses) measured in millimeters. This size controls how much light enters the binoculars.
Understanding Magnification (The First Number: 10x)
Magnification tells you how much bigger an object will look. With 10x binoculars, a bird 100 meters away will look like it’s only 10 meters away. Higher magnification isn’t always better, though.
- Pros of 10x Magnification: Great for bringing distant subjects closer. Ideal for open areas like lakes, seas, or mountains where you need more reach.
- Cons of High Magnification: The image is more sensitive to hand shake. Any small movement is amplified, making the view jittery. They also often have a narrower field of view, making it harder to locate fast-moving objects.
For general use, 8x or 10x are the most popular choices. A lower power like 8x gives you a wider view and a steadier image, which many people prefer for wildlife or sports.
Understanding Lens Diameter (The Second Number: 50)
The second number, 50, is the diameter of each objective lens in millimeters. These are the large lenses at the front of the binoculars. Their main job is to gather light.
- Light Gathering: A larger lens (like 50mm) captures more light than a smaller lens (like 25mm). This results in a brighter image, which is crucial in low-light conditions such as dawn, dusk, or under a forest canopy.
- Image Brightness & Clarity: More light means a clearer, more detailed image, especially when viewing shadows or darker subjects.
However, bigger lenses mean a heavier and larger binocular. A 10×50 model will be significantly bigger than a 10×25 compact model. You’ll need to consider the trade-off between brightness and portability.
The Relationship: Exit Pupil
The combination of the two numbers gives you a third, very important spec: the exit pupil. You calculate it by dividing the lens diameter by the magnification (50 รท 10 = 5).
The exit pupil is the small circle of light you see in the eyepiece when you hold the binoculars away from your eyes. It’s measured in millimeters. This number tells you how bright the image will be for your eyes.
- A 10×50 binocular has an exit pupil of 5mm (50/10=5).
- In bright daylight, your eye’s pupil contracts to about 2-3mm. So, a 5mm exit pupil provides plenty of light, giving a comfortable, bright view.
- In low light, your eye’s pupil dilates to about 5-7mm. A 5mm exit pupil matches this well, making 10×50 binoculars a solid choice for low-light activities like astronomy or dusk wildlife viewing.
If the exit pupil of the binoculars is smaller than your eye’s pupil in the dark, the image will appear dim. That’s why binoculars with a larger exit pupil (like 7mm) are often called “night glasses.”
Is 10×50 Right for You? Best Use Cases
10×50 binoculars are a versatile, mid-to-large size format. They are a fantastic choice for several activities:
- Wildlife Observation: Excellent for stationary viewing of birds and animals, especially in wooded areas or at dawn/dusk where light is limited.
- Astronomy: Their good light gathering makes them very capable for viewing the moon, star clusters, and brighter deep-sky objects. You’ll likely need a tripod adapter for prolonged viewing, as 10x magnification highlights hand shake.
- Maritime & Open Landscape Use: Great for scanning horizons from a steady position on a boat (if stabilized) or from a cliffside.
- Sporting Events: Good for large stadiums where you are seated at a distance, though the field of view might be narrower than an 8x model.
They are likely not the best choice if you need a lightweight pair for hiking long distances, for watching fast-action sports like football where a wide view is key, or for use primarily by children, due to their weight and the challenge of holding them steady.
Key Features to Consider Alongside 10×50
Knowing the numbers is just the start. Here are other critical features to look at:
- Prism Type: Most quality binoculars use either Porro or Roof prisms. Roof prisms are slimmer and more durable, while Porro prisms often offer better depth perception and can be more affordable for a given optical quality.
- Lens Coatings: Coatings reduce glare and increase light transmission. Look for terms like “fully multi-coated” for the best brightness and color fidelity.
- Field of View: This is the width of the area you see, usually measured in feet at 1000 yards. A wider field makes it easier to follow moving objects and scan landscapes.
- Close Focus Distance: The minimum distance at which the binoculars can focus. Important for butterfly watching or looking at details on nearby objects.
- Water & Fog Proofing: O-ring seals and nitrogen purging prevent internal fogging and protect against moisture. Essential for any outdoor use in variable weather.
Comparing 10×50 to Other Common Sizes
- 10×50 vs. 10×42: The 10×42 is the most popular all-around size. The 10×50 will be brighter in low light (5mm vs. 4.2mm exit pupil) but will be heavier and larger. Choose 10×50 for prioritized low-light performance; choose 10×42 for a better balance of performance and portability.
- 10×50 vs. 8×42: The 8×42 has lower magnification (steadier, wider view) and a slightly smaller exit pupil (5.25mm). The 8×42 is often recommended as the perfect starter binocular for its ease of use and versatility. The 10×50 gives you more power for distance but is harder to hold steady.
- 10×50 vs. 12×50: The 12×50 offers more magnification, bringing subjects even closer. However, the image will be noticeably shakier, the field of view narrower, and the exit pupil slightly smaller (4.2mm). A tripod becomes almost necessary for 12x magnification.
Frequently Asked Questions (FAQ)
What do the numbers on binoculars mean?
The numbers, like 10×50, indicate the magnification power and the objective lens diameter. The first number (10x) is the magnification. The second number (50) is the lens size in millimeters.
Are 10×50 binoculars good for bird watching?
Yes, they can be very good, especially in low-light conditions like forests. However, their higher magnification can make them harder to hold steady for long periods compared to 8x models, and they are heavier to carry on long walks.
Can you use 10×50 binoculars without a tripod?
You can, but it requires a steady hand. For extended viewing sessions, particularly for astronomy or detailed wildlife study, using a tripod with an adapter will prevent arm fatigue and give you a rock-solid view.
What is better, 10×50 or 10×42 binoculars?
It depends on your primary use. 10×50 binoculars are better for low-light conditions due to their larger exit pupil. 10×42 binoculars are more compact, lighter, and often provide a better balance of performance and portability for daytime use.
How do I choose binoculars size?
Consider when and how you’ll use them. For bright, active daytime use (hiking, sports), a compact 8×32 or 10×42 is great. For low-light wildlife or astronomy where weight is less concern, a 10×50 or larger is excellent. Always try to hold them first to test comfort and stability.
What does 10×50 mean for night vision?
The 10×50 specification, with its 5mm exit pupil, is well-suited for low-light night viewing. It matches or comes close to matching your eye’s dilated pupil in the dark, allowing a bright image for activities like stargazing or nocturnal wildlife observation.
Understanding what the 10×50 means on binoculars empowers you to make a smart choice. It’s a specification that offers a strong blend of power and light-gathering ability, making it a classic choice for serious hobbyists. Remember to consider the weight and the need for steadiness. The best binoculars are the ones that fit your specific adventures and feel comfortable in your hands, so you can enjoy the view for hours to come.