Scope Magnification: What Do the Numbers on a Scope Mean?

Have you ever wondered what the numbers beside a scope’s name signify and how to read them? Do you want to make sense of this and see how these figures can help you find the best scope for your needs?

Fortunately, I am here to help explain what the numbers mean and how they can help you understand a rifle scope’s magnification and zoom range, as well as its objective lens size and what that means for you, the shooter.

If you have ever asked yourself, “What do the numbers on a scope mean?“, you’ve come to the right place.

I will discuss everything you need to know about rifle scope magnification and adjustment, what the numbers on a scope’s turrets signify, and answer any other questions about your rifle scope.

Where Are the Scope Numbers Located?

The numbers on a rifle scope can typically be found on the right side of the scope’s product name.

The numbers on a rifle scope show you everything you need to know about a long-range scope at a glance.

For example, given the product “Leupold VX-3i 3.5-10×40,” the scope manufacturer would be Leupold.

The VX-3i refers to the product line, and the numbers 3.5-10×40 indicate the specific model, given its zoom capacity and objective lens size.

What Do the Numbers on a Scope Mean?

The numbers on the scope represent the scope specifications when it comes to magnification power and the objective lens diameter.

Once again, using the “Leupold VX-3i 3.5-10×40,” we can see that the first set of numbers (3.5-10x) represents the scope’s magnification range or how many times you can zoom in towards the target.

The second number represents the scope’s objective lens size in millimeters (mm).

What Is Magnification Power in a Scope?

Magnification power refers to how much more magnified an image can appear compared to your naked eye. This allows you to see targets hundreds of yards away as if they were standing before you.

For example, if your scope is labeled 5x, this means that your scope magnification gives you five times the view you would see with your own eyes. The higher the magnification, the farther you can shoot.

Optics companies often provide higher magnification for more accurate distance shooting and variable magnification scopes (those with ranges like 5-24x) for shooting at varying ranges.

The first number is the minimum magnification, while the second represents the maximum your magnification increases to, allowing you to hit different distances you would not have been able to hit at your minimum zoom.

If you are a hunter shooting a specific type of game or working at a single distance, however, you may be able to get by using a fixed magnification scope.

Where Is the Magnification in a Rifle Scope?

A scope’s magnification assembly is located towards the rear of a long-range rifle scope, near the eyepiece or ocular lenses.

The magnification assembly can be adjusted via the ring towards the end (or knob on the side) of a variable magnification scope.

Depending on which direction you turn the ring, you either magnify your view for a longer-range shot or narrow it for a shorter-range one.

What Is the Objective Lens Diameter in a Scope?

The objective lens diameter is the outer diameter housing your scope’s objective lens. The size of the objective lens (aperture) is represented by the number after “x” on a scope’s numbers, measured in millimeters (mm).

For example, “5-25×50” would mean that the diameter of your scope lens is 50 mm, which is a larger size for a scope.

The objective lens indicates how much light can enter your scope.

Similar to the iris in a human eye, a larger objective lens diameter allows more light to enter and pass through the scope tube, providing a clear image even in low-light conditions.

The illumination entering the scope can be measured in foot candles.

Smaller lenses are better suited for binoculars or rifle scopes focusing on a single target. However, larger lenses need more space within the eyepiece, adding more weight to the overall scope.

Where Is the Objective Lens on a Rifle Scope?

The objective lens (aperture) is the circular glass at the front of the scope. The objective bell of the scope surrounds and protects the glass lens.

The tube diameter (mm) measures the central part of this objective bell.

The larger the aperture, the more light can enter the scope. This will then be transmitted to the naked eye.

The scope’s objective lens can also be coated with an exterior coating to protect it against environmental damage, debris, and scratches.

Rifle Scope Magnification and Size Chart

When reading a scope magnification chart, many shooters must remember the following: Magnification, Magnification Type, and Aperture size (objective lens diameter).

For example, scopes listed with 4x can only be magnified by a single setting on the scope. We call these types “fixed magnification.”

Meanwhile, the first number before “x”, such as “4-12x”, represents the minimum and maximum zoom range on a variable magnification scope.

These numbers on your scope mean you can adjust from four to twelve times the regular view as your magnification range, allowing you to hit longer distances at the cost of only some eye relief.

These scopes provide you with more options, and wider magnification brings you a higher maximum magnification, more versatility in the field, and the ability to work in a variety of hunting and tactical applications.

The Magnification Equation and Image Perception

Magnification can make far-away targets appear as if they were standing right in front of you.

While it would be almost impossible to see a target from 300 yards away with your naked eye, a magnified scope can make the distance seemingly disappear.

For example, 3x magnification can allow you to see a target 300 yards away as if it were only 100 yards away. This means that the higher the magnification, the closer the target appears to your eyes.

What Are the Effects of Increasing Magnification?

Increasing your magnification can result in a more narrow field of view, while decreasing it does the opposite.

While a wider field of view is better for rapid target acquisition, narrowing your FOV makes aiming at a target farther away much easier, as the target will appear much closer than it actually is.

This alteration of your FOV will also lead to a smaller exit pupil (diameter through which light leaves the scope and enters the eyes), which could make a dimmer image due to low light conditions at higher magnifications.

Increased magnification can also reduce eye relief, as a higher magnification scope will move closer to your eyes, leading to more opportunities for scope aberrations.

What Are the Physical Limitations of Magnification?

While having suitable magnification ranges and options will make your sight picture clearer, allowing you to place your reticle on target, some lenses can create optical distortions that will leave you worse off.

Here are some physical limitations of magnification that can ruin your ability to aim and hit your target, as well as the effects eye relief and exit pupil have on image clarity.

TAKE NOTE: These issues can affect old and new scopes alike.

Chromatic Aberration

Chromatic aberration or fringing of the lenses causes a rainbow effect to appear as if you are viewing your sight picture through a prism.

Chromatic aberration occurs when there is too much magnification. This is because the lens system cannot bring the colors into a common focus, causing them to splay out in a way that distracts the user.

It leaves you with an incomplete sight picture that can be detrimental in the field. This can happen to cheap and quality optics alike.

Spherical Aberration

Like chromatic aberration, spherical aberration increases your risk and decreases your ability to aim as you ratchet up your magnification.

This aberration happens as your vision becomes blurry at the edges while remaining somewhat clear in the center.

This happens when light rays at the periphery of the scope meet at a different focal point from the light rays passing through the center.

Like field curvature, the edges near your target are blurry, leaving you with no peripheral vision of your target area.

Field Curvature

Field curvature occurs when an image’s sharpness is not uniform across the entire field of view. This is because lenses do not project images on a flat plane but on a curved surface.

This results in blurriness at the edges of your images with clarity in the center, or vice versa, especially on scopes with low magnification.

Field of View

Field of view is the measured area of available space seen through your scopes, measured as a linear distance in feet at 100 yards. The FOV shifts as you zoom in and out.

Magnification affects an entire field of view by narrowing or expanding your target. You can calculate the field of view by dividing the objective lens diameter by the magnification setting.

When you magnify the target more, your field of view becomes smaller. This results in the area around your scope becoming less visible. You must adjust your FOV, or the only clear part of your sight picture will be your reticle.

Dimness

Dimming is often the result of thicker lenses or poor optical quality. This is due to light being reflected and absorbed by the scope, keeping it from being transmitted into the eye of the user, leading to a darker sight picture that melds with the reticle.

Thicker lenses used for higher magnifying capabilities tend to dim their target more than scopes with lower magnifying capabilities.

What Is the Importance of Choosing the Right Magnification?

Choosing the correct magnification can help you make the most shots and improve accuracy.

The right amount of magnification can make your target larger and easier to aim at, while too much can lead to aberrations that ruin your aim.

The following are my recommended settings for different shooters and shooting ranges.

• General shooters can rely on a variable magnification of 10x and above for targets at around 500 yards.
• Hunters would prefer 4-6x magnification for a hunting game at around 100-200 yards.
• I recommend using more powerful rifle scopes for further and smaller targets.

Frequently Asked Questions (FAQs)

Here are some frequently asked questions regarding scope numbers that you can consider.

Should You Use Fixed Scope or Variable Scope?

Your choice of scope magnification will depend on your target. A fixed scope is ideal for close-range targets at your typical engagement distances. On the other hand, a variable scope is ideal if you are hunting different types of game or working with varying engagement distances.

If you need a variable scope that is not too overwhelming with zoom levels, you can choose a Low Power Variable Optic (LVPO), which starts at 1x magnification and can give you the ideal level of zoom for your needs.

What Other Numbers Are Associated With the Scope?

Besides magnification settings and objective lens diameter size, other numbers on a rifle scope represent lens diameter in millimeters and the illumination entering the scope, measured in foot candles (lumen/square foot).

Final Thoughts on Rifle Scope Numbers and Magnification

The numbers on a rifle scope refer to the magnification range the scope offers, as well as the objective lens size in millimeters, which can determine how much illumination your scope can handle.

While it may seem like a no-brainer that wider and higher magnification ranges and larger objective lenses can lead to better performance, those factors alone do not guarantee scope accuracy.

After all, too much magnification can result in blurrier or dimmer imaging and can even affect eye relief, and a larger objective lens can lead to a heftier optic.

Now that you know what the numbers mean, you may be ready to choose a rifle scope that meets your specific use case and mission type.