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Choosing the “right” gear for your outdoor adventures can be a daunting job – so many options, a wide range on the budget scale, and tons of well-intentioned opinions on what’s “the best.”
Selecting the right optics is no different. With endless offerings on brands, quality, magnifications, and durability, it can be hard to choose the best optic for your intended use. Not to mention, many outdoorsmen and women use their optics for various purposes–hunting, birding, star-gazing, sightseeing, sporting events… you name it.
Now, this might sound a bit rudimentary, but on a foundational level, it’s essential to understand what the numbers on optics are referring to. Let’s break down exactly what those numbers mean and some of the specs and features that can help you decide the best choice for you and your needs.
WHAT DO THE NUMBERS MEAN?
Optic numbers refer to the magnification and objective lens diameter, denoted by two numbers separated by an "x." For example, a pair of binoculars marked as "10x42" indicates a magnification of 10 times and an objective lens diameter of 42 measured in millimeters.
On a spotting scope or a rifle scope, you will see another number as well. A spotting scope marked 25-50x80 identifies the magnification range, 25-50 times magnification, followed by the number 80,
the objective lens diameter is measured in millimeters. The same is true for rifle scopes. The first numbers tell you the magnification range; the last number refers to the objective lens diameter, measured in millimeters.
The magnification number indicates how much larger the object being viewed will appear through the respective optics compared to the naked eye. For example, an object that appears 100 yards away would appear as if it were only 10 yards away when viewed through a 10x magnifying optic.
The objective lens diameter determines the amount of light that can enter the optic. A larger objective lens diameter means more light can enter, making the image brighter and clearer, especially in low-light conditions.
It's important to note that optics with higher magnification don’t necessarily equate to being better, as they are heavier, can be more expensive, and are more difficult to hold steady without a tripod or other stabilizing rest.
WHAT DOES THAT MEAN FOR YOU?
For hunting or birding, it’s generally recommended to choose a magnification power of 8-12x for an all-purpose binocular. This range provides a good balance between magnification and field of view. Higher magnification binoculars can be harder to hold steady and will have a narrower field of view, making it harder to find moving targets, but they do allow you to see more detail. Conversely, lower magnifications are easier to handhold and have a larger field of view; however, they don’t offer as much magnification.
Because objective size and magnification are directly related, exit pupil is another thing to consider when choosing an optic. Exit pupil refers to the size of the beam of light that exits the optics and enters your eyes and directly correlates with the image's brightness and clarity. It is calculated by dividing the objective lens diameter by the magnification power (e.g., for a 10x50 binocular; 50mm/10mm = 5mm). It’s recommended to choose binoculars with an exit pupil around 5mm or larger. This provides a good balance between brightness and magnification and can improve your optic’s low-light capabilities, extending your glass use into the dawn and dusk hours. So, if you decide to go with a higher magnification optic, understand that you’ll benefit from an optic with a larger objective.
"OPTIC NUMBERS REFER TO THE MAGNIFICATION AND OBJECTIVE LENS DIAMETER, DENOTED BY TWO NUMBERS SEPARATED BY AN "X." A SPOTTING SCOPE THAT'S MARKED 25-50X80 IDENTIFIES THE MAGNIFICATION RANGE, 25-50 TIMES MAGNIFICATION, FOLLOWED UP BY THE NUMBER 80, THE OBJECTIVE LENS DIAMETER MEASURED IN MILLIMETERS."
Just as the exit pupil is in part measured by an optics magnification, magnification plays a vital role in the field of view. Defined by the width of the image you see through your optics, the field of view is determined by ocular and prism designs. If your primary use is for birding, an optic with a larger field of view will open up what you can see at one time, helping you find what you’re looking for while also making it easier to track subjects when they’re on the move. Generally speaking, a lower magnification will offer you a larger field of view, while a higher magnification will reduce your view.
Magnification also plays a role in eye relief, another consideration when shopping for glass. Eye relief
is the distance at which the image is full and is measured as the distance between the eyepiece and your eyes. This is particularly important for rifle scopes since shallow eye relief could lead to injury due to rifle recoil. It’s also important for eyeglass wearers who prefer to look through optics while wearing their glasses.
KNOWLEDGE IS POWER
At the end of the day, there are a lot of optic manufacturers on the market! Settling on “the right one” can be a bit harder than making a quick purchase. Knowing what the numbers mean can help you make an educated decision about which optics are best for you and your needs.
If you still have questions on how these numbers affect an optic, consider giving the Maven Demo Program a try. You’ll be able to try out a variety of magnifications/objective size configurations and see firsthand how each directly affects your viewing experience.
Use the discount code COURTNEYPRETE-GIFT to get a free gift with your on your new optic purchase.
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