OPTICS

What is a Rifle Scope?

A rifle scope is an essential tool for any shooter, designed to bring distant targets into clear focus. Especially in hunting and precision shooting, a rifle scope is indispensable as it helps in aiming accurately and hitting your target. Choosing the right scope depends on various factors such as magnification, size, and the type of reticle.

How to Use a Rifle Scope?

A common question is how to look through a rifle scope. Hold the scope about a fist's distance from your eye for a clear and full view. Experiment with the distance to find the optimal view without any blurred edges. A well-adjusted scope ensures that your target is sharp and clear, which is crucial for accurate shooting.

Types of Reticles

Scopes come with various types of reticles, such as crosshairs, MilDot, and Circle Dot. Each reticle type offers unique benefits:

• Crosshairs: Ideal for precise aiming at clearly defined targets.
• MilDot Reticle: Provides accurate range estimation and compensation for weather conditions.
• Circle Dot: Less common, but preferred by some shooters for specific targets.

Magnification and Objective Lens

The numbers on a scope, such as 4x40, indicate the magnification and the diameter of the objective lens. These features affect various aspects of your shooting experience:

• Magnification (e.g., 4x): The first value in the scope’s designation indicates the magnification. A 4x magnification means that the target appears four times larger than with the naked eye. Higher magnification offers more detail, which is useful for long-range shots. However, too high magnification can also have drawbacks, such as a narrower field of view and increased sensitivity to weapon movement and vibrations.

• Objective Lens Diameter (e.g., 40 mm): The second value in the scope’s designation indicates the diameter of the objective lens in millimeters. A larger objective lens captures more light, resulting in a brighter image, especially in low light. This is essential for hunting at dusk or in dense areas. However, keep in mind that larger objective lenses make the scope heavier and bulkier, which can affect the balance of your weapon.

Key Features of Magnification and Objective Lens

• Fixed vs. Variable Magnification: Scopes can have fixed or variable magnification. Fixed magnification means that the magnification cannot be adjusted, which is simpler and often more robust. Variable magnification, such as 3-9x, allows the shooter to adjust the magnification for different shooting situations, offering more flexibility but also adding complexity.

• Field of View: The field of view (FOV) becomes smaller as magnification increases. This means that at higher magnifications, the visible area becomes smaller, making it more challenging to track moving targets. At lower magnifications, the field of view is wider, which is beneficial in dynamic shooting situations.

• Light Transmission: Larger objective lenses allow more light to enter, which is important for brightness and image quality. This is crucial when shooting in low-light conditions. The quality of the lens coatings also plays a significant role in maximizing light transmission and minimizing reflections and glare.

• Exit Pupil: The exit pupil is the diameter of the light that passes through the eyepiece lens and can be calculated by dividing the objective lens diameter by the magnification. A larger exit pupil means that more light reaches your eye, resulting in a brighter image. This is especially important when shooting in low light. For example, a 4x40 scope has an exit pupil of 10 mm (40/4 = 10).

• Eye Relief: Eye relief is the distance between the eyepiece and your eye where you can see the full image. This is important for preventing eye injury from recoil, especially with more powerful rifles. Scopes with long eye relief are safer and more comfortable to use.

IR and AO

• IR (Illuminated Reticle): Illuminates the crosshair for better visibility in low light conditions.
• AO (Adjustable Objective): Adjustable lens for focusing at different distances.

Mounting and Parallax

Mount your scope as low as possible above the barrel with suitable mounting rings. Parallax refers to the apparent shift of a target when the viewing angle is changed. Higher-end scopes have an adjustable parallax to minimize these errors. Correctly setting the parallax ensures a more accurate shot, especially at different distances.

Red Dot Scopes

A red dot system uses a red dot as an aiming point, simplifying aiming without magnifying the image. Red dots are ideal for situations where quick and accurate aiming is important, such as in tactical shooting scenarios and dynamic shooting sports.

The Basics of Scopes and How They Work

Lens in a Scope

The main components of a scope are the lenses: the objective lens, erector lens, magnification lens, and eyepiece lens. The objective lens is located at the front of the tube and gathers light, which is then transmitted to the erector lens that inverts the image. The magnification lens enlarges the image, which is ultimately viewed through the eyepiece lens, close to the user’s eye.

Operation of the Lenses

Light passes through the objective lens and is focused to a point within the scope, known as the focal point. The image is then inverted by the erector lens and passed to the magnification lens, which adjusts the magnification by moving toward the objective lens for increased magnification, and toward the eyepiece for decreased magnification. The eyepiece lens focuses the light and presents the image you see when looking through the scope.

Eyepiece and Eye Relief

Eye relief is the distance between the shooter’s eye and the eyepiece where the full field of view is visible. Shorter eye relief means the scope needs to be mounted closer to the face, while longer eye relief, as seen in scout rifles, provides more space between the eyepiece and the eye, allowing for mounting further forward on the weapon.

Waterproof and Fogproof

Most scope lenses are waterproof and fogproof, essential for various shooting conditions. Waterproof scopes feature O-rings to keep moisture and dust out. To prevent condensation, the air inside the tube is replaced with gases like nitrogen or argon, which do not contain moisture.

Scope Magnification

The magnification of the scope indicates how many times larger the image appears compared to the naked eye. Some scopes have fixed magnification, such as a 3x40 scope that magnifies the image three times. Other scopes have variable magnification, denoted as 3-9x40, meaning the user can adjust the magnification from three to nine times.

Reticles and Their Functions

The reticle, usually a crosshair pattern, can consist of fine wires or be etched on a glass plate. Different types of reticles, such as duplex, crosshairs, mil-dot, special purpose reticles (SPR), and bullet drop compensators (BDC), are designed for specific applications or ammunition calibers.

Setting Up and Adjusting the Scope

Use the windage (horizontal) and elevation (vertical) adjustments via knobs or turrets to zero the scope, so that the desired target is in the center of the reticle. Reticles such as mil-dot and BDC have markings to estimate where shots will land at different distances without resetting the scope.

Mounting the Scope

When purchasing a scope, it’s important to know how it should be mounted on your weapon and what size mounting rings are needed. Modern rifles often come with mounting bases such as a dovetail or a 1913 Picatinny rail. Mounting rings can be either two separate pieces or a single piece and should be properly matched to the diameter of the scope tube (1 inch or 30 millimeters).

Height of the Mounting Rings

The height of the mounting rings depends on various factors such as the cheek rest on the stock, eye relief, the diameter of the objective lens, the type of action, and the bolt lever. Lower rings place the scope closer to the rifle, requiring a lower position for a good view, while higher rings provide more space for larger objective lenses and bolt-action handles.

Aligning the Reticle and Adjusting Eye Relief

The reticle of your scope is the image you see on the lens that indicates where the weapon is aimed. It’s usually a cross, but many variations are possible, such as circles and Xs. With the mounting rings loose, rotate the scope until the reticle is properly aligned. Then adjust the distance from the lens to your eye to ensure it doesn’t hit your eye during recoil.

Different Parts of the Scope

While there are many manufacturers, almost all use the same basic components: the housing, the eyepiece, the objective lens, the shoulder, and the knobs for windage, elevation, and parallax. The shoulder of the scope is where the diameter increases to hold the objective lens. The windage and elevation knobs move the reticle sideways and up and down, respectively. Parallax knobs are rarely adjusted and affect the movement of the reticle relative to the target.

Using Fixed or Variable Magnification Lenses

A fixed lens offers one level of magnification, while a variable lens has a ring that allows you to choose between different levels of magnification. Most scopes are fixed, but if you have a variable lens, you can adjust the magnification with the ring between the shoulder and the objective lens.

Evaluating Magnification Levels

You can determine the power of your scope by looking at the model number. A scope with the model number "4 x 30" means that the image appears four times larger through the scope than with the naked eye, and the objective lens has a diameter of 30 millimeters. Variable power models such as "4-12 x 32" mean that the magnification can be adjusted between four and twelve times.

Eye Relief

Eye relief is the distance from the eyepiece to your eye where you can see the full field of view. Stronger magnification requires narrower eye relief to see your target properly. Eye relief distances are often indicated as a range, such as 3-9x, meaning the correct eye relief is between 3 and 9 inches from the eyepiece.

Sight Picture

Without a scope, a good sight picture involves aligning the rear and front sights. With a scope, it’s about centering the reticle in your field of view and positioning it over your target. Your sight picture should form a perfectly centered circle with no black edges on one side.

Adjusting Based on the Impact of Your Rounds

Be as consistent as possible when firing rounds at the target and assess where they land. If you’re consistent, the rounds should land in the same area. Adjust the windage to move the impact left or right and the elevation to move the impact up or down.

Adjusting Parallax

Some advanced scopes allow you to adjust a third variable: parallax. Parallax is the movement of the target relative to the reticle when you move your eye. A parallax issue can cause the target and reticle to appear on different optical planes. Adjust the parallax by moving your head while looking through the scope and adjusting the parallax knob until the reticle no longer appears to move.

Zeroing the Rifle

Once you understand how to adjust the scope, you can zero the rifle. This involves shooting at a known distance and adjusting the scope so that the reticle precisely matches the impact point of the rounds. Use a bipod or shooting table to keep the weapon steady while shooting to eliminate variables such as heartbeats, breathing, and muscle fatigue.

Maintaining and Storing the Scope

Protect your scope’s lenses with lens caps when not in use. Use a lens brush to remove dirt or sediment and avoid cleaning the lenses with non-optical cloths. Use lens cleaning fluid and microfiber cloths to remove fingerprints or smudges. Store your scope in a cool, dry place away from direct sunlight and extreme temperatures.