Binoculars are an essential tool for anyone who enjoys outdoor activities, hunting or shooting.
If you’ve never bought a pair of binoculars before, it can be tricky to understand which binoculars will give you the performance you need.
If you’re not sure how to tell what magnification a pair of binoculars has, or what some of the other numbers used to describe binoculars mean, this is the right article to be reading.
In this article, we will explain the meaning of the different numbers on binoculars and what you need to know to make an informed purchase.
What do Binocular Numbers Mean?
Binoculars are typically labeled with two numbers, such as 10×42 or 8×30. The first number represents the magnification, or how many times closer the object appears than it does to the naked eye. The second number represents the diameter of the objective lens, which is the lens on the end of the binoculars farthest from your eye.
The size of the objective lens determines how much light is let into the binoculars and thus how bright the image appears to your eyes.
Between the magnification and the objective lens diameter, you can get a basic idea of how the binoculars will perform in certain situations.
The higher the magnification, the better the binoculars will be for seeing further away, but the worse they’ll be for seeing things that are closer.
If what you’re looking at is only 100 yards away, for example, you might not want anything stronger than 10x.
In that case, a 20x pair of binoculars could make the image too large and make it harder to even find the target in the first place.
Binocular Magnification and Size of Objective Lens: All You Need to Know
1. Magnification Number and Explanation
The magnification number on binoculars can range from as low as 6x to as high as 20x or more.
A higher magnification can make distant objects appear closer and more detailed, but it can also make the image shakier and harder to keep steady.
A lower magnification, on the other hand, can provide a wider field of view and a steadier image, but may not offer as much detail.
Understanding magnification is fairly simple: a 10x pair of binoculars, for example, will essentially make an object appear 10x larger than it does with your naked eye.
Another way of saying it is that it makes an object that is 100 yards away as large as it would be if it were only 10 yards away.
An important note here is that binocular zoom isn’t adjustable. There’s no such thing as a pair of binoculars that goes from 5x to 10x, or 10x to 20x, or anything like that.
They magnify a specific amount, and that’s it. This is why it’s critical to get the binoculars that give you the right amount of magnification for what you’re doing.
2. Objective Lens and Why it Matters
The size of the objective lens on binoculars can range from as small as 20mm to as large as 80mm or more.
A larger objective lens can gather more light and produce a brighter, sharper image, especially in low light conditions.
However, a larger objective lens can also make the binoculars heavier and bulkier, and may require a larger tripod or mount.
A smaller objective lens can make the binoculars more compact and lightweight, but may not offer as much brightness or detail.
Much like magnification, this is a matter of balance – getting the best image you can get while keeping the binoculars to a usable size, weight, and price.
Not surprisingly, binoculars with larger objective lenses tend to be more expensive, and if you’re only planning on using them in good lighting conditions anyway, sometimes bigger isn’t noticeably better.
As a bit of an image snob, I am almost always willing to inconvenience myself for a little bit more image quality, but I spend a disproportionate amount of my time looking through rifle scopes, camera lenses, and binoculars, so for someone who just wants a good look at the bird in their backyard, it may make more sense to get the lighter and cheaper pair that does just as well.
Is Bigger Better?
Let’s go into more detail on this question.
When it comes to objective lens size, as mentioned above, bigger is not always better. A larger objective lens can offer better image quality in low light conditions, but it can also make the binoculars heavier and harder to hold steady.
Binoculars are already difficult to keep lined up with your eyes, and a little weight can make it that much harder.
If you have the ability to rest your elbows on something while you hold the binoculars, or even mount them on a tripod, you can deal with this well enough, but it’s something you have to worry about when you get larger, heavier binoculars.
If you’re working in low light, such as for astronomy, then you want the biggest objective you can get.
When it comes to magnification, more is not necessarily better either, but we’ll talk more about that in the next section.
What Magnification Should I Get?
The best magnification for you will depend on what you’re using the binoculars for.
If you plan to use your binoculars for birdwatching or other outdoor activities, I recommend a magnification between 8x and 10x.
This range provides a good balance between detail and stability, and allows you to see a wide field of view.
For things like astronomy, you want as high of magnification as you can get – just be prepared to stabilize the binoculars more based on the amount of magnification you’re using.
You can still see interesting things in the sky with as little as 7x magnification, but things like the moon and other celestial bodies can be seen with much more detail as you go up in magnification.
Check our guide on ‘best spotting scope for target shooting’.
Are Expensive Binoculars Better?
Usually, yes, but expensive binoculars are not always better than cheaper models. While high-end binoculars may offer better image quality, durability, and features, they may not be necessary for casual users or those on a budget.
Of course, there are premium brands where the price reflects the name of the brand more than the specs you’re getting, but by and large you get what you pay for.
Again, it comes down to your specific use. Are you wanting to see a bird clearly from 20-30 yards away, or 200 yards away?
Are you trying to see little tiny bullet holes in a paper target that is 300 yards downrange, or just seeing which gong is moving after your buddy takes a shot?
The higher the level of detail and distance, the more you should expect to pay.
Other Numbers on Binoculars
1. Field of View
Field of view is another important number to consider when choosing binoculars. Field of view refers to the width of the area that can be seen through the binoculars at a certain distance.
It is usually measured in feet at a distance of 100 yards, but might also be shown as an angle (e.g. 20 degrees).
Either way, the wider the field of view, the more you can see without moving the binoculars. This is especially important for activities such as birdwatching or hunting, where you need to quickly locate and follow moving objects.
Wider field of view makes for a more pleasant viewing experience, so all other things being equal, I’d recommend looking for the widest FOV you can get.
The field of view is influenced by both the magnification and the objective lens diameter. As magnification increases, the field of view decreases.
Conversely, as the objective lens diameter increases, the field of view also increases.
That said, not every 10×50 pair of binoculars has exactly the same field of view; FOV can also be affected by the distance between the lenses and how many elements are used to result in the end magnification.
The weight of the binoculars is another important factor to consider, especially if you plan on looking through them for an extended period.
The weight of binoculars can vary greatly, from lightweight models that weigh just a few ounces to heavy-duty models that weigh several pounds.
For the most part, they won’t weigh enough that they become a huge factor as you’re hiking somewhere (though some can get that heavy), but the weight makes a big difference as you’re holding them up to your eyes.
Even if you’re using a tripod, you can get away with a flimsier, cheaper tripod when you’re using lighter binoculars.
Lighter doesn’t necessarily mean cheaper or lower quality, either.
Sometimes expensive binoculars that are designed for hikers or backpackers are made out of lightweight materials like magnesium alloys, which gives you as much durability in a lighter frame.
Weight should be a factor in your decision, but whether it needs to be a major factor is up to what you plan to do with them.
3. Eye Relief
Eye relief is the distance between the eyepiece and your eye when the entire field of view is visible.
It is an important factor to consider, especially if you wear glasses or have other vision impairments. If the eye relief is too short, you may not be able to see the entire field of view or may have to strain your eyes to see it.
This can be uncomfortable and even painful over time.
This is my biggest complaint with binoculars in general. I don’t understand why so many bino manufacturers feel the need to make users of their products jam the binos into their skulls and rub their eyeballs directly onto the glass to get a full picture.
Finding binoculars with an inch or so of eye relief is a dream come true, though they can be more difficult to stabilize by hand.
Eye relief is usually measured in millimeters, longer eye relief may be even more important for those who wear glasses.
A longer eye relief allows you to position the eyepiece further away from your eye, which can help reduce eye strain and provide a more comfortable viewing experience.
4. Diopter Adjustment Range
Diopter adjustment is a feature that can be found on many binoculars that is used to adjust the focus of the binoculars to compensate for differences in vision between the user’s eyes.
The diopter adjustment is located on one of the eyepieces and allows you to adjust the focus of one eyepiece independently of the other.
The point of this is to accommodate for the differences between your eyes, much like an optometrist will prescribe slightly different contact lenses for a patient’s left and right eye.
If you don’t need corrective lenses, chances are your eyes are close enough that you won’t notice the lack of a diopter adjustment, though it’s still a good idea to try it out and see.
Most binoculars have a diopter adjustment range of +/- 3 diopters. This is enough for most people, but some people may need a greater range of adjustment.
If you have a strong prescription in one or both eyes, you may need to look for binoculars with a greater diopter adjustment range.
5. Minimum Focus Distance
The minimum focus distance is the closest distance that you can focus on an object with your binoculars.
This doesn’t come up as often because the whole point of binoculars is to see things that are far away, but if you have fantasies of using your binoculars as a magnifying glass, you will likely be disappointed.
Feel free to check what the minimum focus distance of each pair of binoculars is, but it shouldn’t be a large factor unless you’re trying to see things very close up.
The minimum focus distance varies from binocular to binocular, but most binoculars have a minimum focus distance of around 6-8 feet. That said, some binoculars have a minimum focus distance of as little as 2-3 feet.
Types of Lenses
When it comes to binocular lenses, there are two main types: plastic and glass.
Glass lenses are generally considered to be of higher quality than plastic lenses, as they provide better image quality and are more durable.
Plastic lenses are less expensive and lighter than glass lenses, but they can scratch easily and are more prone to distortion.
They typically don’t have nearly as good of light transmission and will not last as long. It’s far better to have a plastic casing than to have plastic lenses.
Glass lenses are heavier than plastic lenses, but they are more durable and provide better image quality. Essentially, glass lenses are better in every conceivable way except that they’re more expensive to manufacture.
Clear plastic lenses are not any more durable than good glass lenses, and the protective housing of the binoculars should handle normal wear and tear.
3. C (Coated)
C (Coated) lenses have a single layer of anti-reflective coating on the front lens element. This can help to reduce glare and improve image contrast, but doesn’t do much else and only has so much effectiveness.
4. MC (Multi Coated)
MC (Multi Coated) lenses have multiple layers of anti-reflective coating on the front lens element. This can provide even better glare reduction and image clarity than C lenses.
Each coating usually has a special function to improve some aspect of the image that you are seeing. That said, not all multi-coatings are created equal, and some will perform better/worse than others.
5. FC (Fully Coated)
FC (Fully Coated) lenses have anti-reflective coating on all air-to-glass surfaces, including the ocular lens. This can provide excellent image clarity and contrast, but may only improve one aspect of the image.
6. MFC (Multi Fully Coated)
As you might guess, MFC (Multi Fully Coated) lenses have multiple layers of anti-reflective coating on all air-to-glass surfaces.
If you want the best possible image out of your binoculars, you want to find ones that have MFC lenses. The coatings can make a significant difference in not only image quality, but also durability.
Choosing binoculars can be as simple or as complicated as you want. At the minimum, you want to choose the magnification and objective lens diameter that are most appropriate for what you’re using the binoculars for.
If you want to dive deeper, you can start to compare field of view, eye relief, weight, diopter adjustment range, and even minimum focus distance.
I would generally advise staying away from plastic lenses unless the binoculars are for a child, but you can choose binoculars with the level of coating that you feel like will work best for what you’re doing.
Binoculars are pretty cool tools, but it can be frustrating when the ones you have are not the ones you need. Putting a little thought and time into which ones you buy can make a huge difference later on.