A Beginner’s Guide
A rifle scope is more than just an accessory—it’s an essential tool that can significantly improve your shooting accuracy. Whether you're venturing into hunting, sports shooting, or long-range precision shooting, understanding the key components and functions of a rifle scope is critical to getting the most out of your shooting experience.
What is a Rifle Scope?
At its core, a rifle scope is an optical instrument designed to assist shooters in aiming accurately at distant targets. It achieves this by magnifying the target and providing a more precise point of focus. Without a scope, shooting at long distances can be nearly impossible for most shooters due to the human eye’s limitations.
Scopes can vary greatly in design, features, and performance. While some are highly specialized for specific tasks (such as tactical shooting or hunting in low-light conditions), the basic concept remains the same: to provide a clearer, magnified image of the target and offer precise aiming capabilities.
Key Components of a Rifle Scope
While rifle scopes can have various features depending on the model and brand, they all share several core components that define how they function. Here’s a more detailed look at each one:
1. Objective Lens
The objective lens is typically the larger lens at the front of the scope (LPVO's usually have a smaller objective lens like a 24mm). Its primary function is to collect light, which is critical for providing a bright and clear image of your target. The size of the objective lens is usually measured in millimetres (e.g., 40mm, 50mm), and the larger the diameter of this lens, the more light it can gather.
Why does this matter? A larger objective lens will result in a brighter image, which is especially important in low-light conditions such as early morning or dusk. However, it’s important to note that larger lenses can also increase the overall size and weight of the scope, so there’s a trade-off between light-gathering ability and portability. A larger Objective lens also makes the scope's depth of focus shallower. This means the shooter must be precise with their focus to get a clear image.
2. Eyepiece (Ocular Lens)
The eyepiece or ocular lens is located at the opposite end of the scope from the objective lens. It’s the part of the scope that you look through. Most eye-pieces contain a dioptre focus; this focus is used to make up for the shooter's vision. The dioptre adjustment is not used to focus the image, instead, it is used to make sure the reticule is clear and sharp for the shooter. (It is worth noting that if the dioptre adjustment is used, the parallax distance markers will no longer be true.)
Eye relief (the distance between your eye and the eyepiece) is a crucial consideration here, as it can prevent injury from the recoil of the rifle, especially when using high-powered firearms. A typical eye-relief is 4 inches or 100mm
3. Magnification
One of the most important features of a scope is its magnification range. This is the degree to which the scope can enlarge the image of the target. For example, a 3-9x magnification means that the scope starts at 3x and has a maximum magnification of 9x.
Magnification can make identification and target acquisition quicker and easier, especially at longer distances, but higher magnification does have trade-offs:
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Field of View (FOV): Higher magnification means a narrower field of view. At 3x magnification, you will see a far wider area than at 9x. This can be a challenge when tracking moving targets.
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'Wobble' - Magnification, magnifies everything, this includes the shooter's natural shake or 'wobble' this can make it feel harder to keep the sights on target.
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Cost - Higher-magnification scopes typically cost more than lower-magnification scopes. This is because higher-magnification scopes usually require higher-quality glass that does not distort the image as you zoom in.
Most modern scopes are variable power, i.e. 3-9x, but there are also 'fixed' power scopes such as the Optisan CP 10x32. The benefits of a fixed power scope are a brighter image, simpler to use, and a lighter scope, and they are usually cheaper to manufacture. The downside of fixed power scope is that they tend to be less versatile than variables.
4. Reticle
The reticule is what the shooter uses to aim their rifle, sometimes referred to as a crosshair (the term comes from very early scopes using fine hairs to form a cross to make an aiming point). There are many different styles of reticules for different uses and preferences. It is up to the shooter to select which one will suit their application the best.
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Standard Crosshairs: The most basic type, consisting of a simple vertical and horizontal line, used primarily for benchrest nowadays.
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G4/German dot: This is the quintessential stalking reticule found in many hunting scopes; it features a floating dot with only 3 posts. This gives the shooter an unobstructed view of their quarry with a simple to use aim point
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Mil-dot Reticule: Originally a military reticule, it features a standard cross with 'dots' spaced at 1 milliradian (or 1 Mil-dot). This is a very good general use reticule.
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Mil-Hash: this is the same as the Mil-dot reticule, but instead of 'dots' it uses 'hashes' or lines. This style of reticule has become more popular than the Mil-dot in recent times.
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BDC (Bullet Drop Compensator): A specialized reticule with pre-marked dots or lines that help compensate for bullet drop at various distances. This type of reticule is used in a lot of modern hunting scopes.
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Grid/Christmas-tree: an increasingly popular option. This is the 'busiest' reticule type that gives the shooter lots of aim points for drop and windage. Grid reticules are very popular amongst PSR and long-range shooters.
The choice of reticle is a personal preference, while there may be reticules better suited to a particular task, the best advice is for the shooter to use a reticule that suits them and their eye the best.
5. Turrets
Pretty much all scopes (bar some very niche examples) will have adjustment turrets. These turrets are what the shooter uses to adjust the reticule in relation to the point of impact (where the shot is going). The top turret is always the elevation (up and down), and the windage (left and right adjustment) turret is usually located on the right-hand side.
Turrets adjust in something called 'clicks'; this term comes from the sound turrets make as they adjust. There are two units of adjustment in shooting today: Minute of Angle (MOA) and Milliradian (MRAD/Mil).
MOA
A Minute of Angle (MOA) is an angular measurement. This means it changes over different distances. MOA is based on a circle with a radius of 100 yards or a diameter of 200 yards.
An MOA is 1/60th of a degree.
1 MOA is 1″ per 100 yards. (actually 1.047″, but very few people need to be this precise)
1 MOA is a different size at different distances; 5″ at 500 yards is still just 1 MOA.
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Scopes using MOA rarely adjust by 1 MOA at a time (some red dots do). The most common adjustment amount is ¼ MOA; this means at 100 yards, one click equals ¼ inch of movement.
Some other adjustment mounts are ½ MOA (seen in red dots and LVPOs), 1/8 MOA (Popular for benchrest), 1/10 MOA (not very common)
MRAD/Mil
A Milliradian (MRAD/Mil) is an angular measurement. This means it changes over different distances. MRAD is based on a circle with a radius of 100 meters or a diameter of 200 meters.
An MRAD is a thousandth of a radian (0.001 radian).
1 MRAD is 10cm per 100 meters.
1 MRAD is a different size at different distances; 50cm at 500 meters is still just 1 MRAD.
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Scopes using MRAD never adjust by 1 MRAD at a time (this would never be precise enough). The most common adjustment amount is by 0.1 MRAD; this means at 100m, one click equals 0.1 MRAD of movement (1cm).
Another adjustment mount is 0.05 MRAD (seen in precision long-range scopes).
6. Parallax Adjustment
Parallax is a phenomenon where the reticule appears to shift in relation to the target due to the difference in distance between the reticule and the target. This can result in a misalignment between where you aim and where the bullet impacts, especially at long ranges.
A parallax adjustment feature allows you to fine-tune the reticule's focus to eliminate parallax error. It’s especially useful when shooting at targets at various distances. The parallax adjustment typically appears as a knob or dial on the side of the scope (some older/more traditional scopes have this adjustment at the objective lens i.e. AO scopes).
For most shooters, parallax appears as the focus of the image. To know whether or not you have adjusted for parallax, simply see if the image is in focus (this is good enough for most shooters).
If you are taking part in a precision discipline (especially if you use a high-power scope), then the best way to check for parallax is to 'bob' your head and see if the reticule moves. If the reticule stays where it is, then parallax has been correctly adjusted for.
- Magnification Adjustment Ring: This is the dial located on the ocular side of the scope (the part your eye goes against). It allows you to zoom in and out on your target.
- Reticle Focus: The dial ring closest to the edge of the ocular side of your rifle scope. This will help focus your reticle (crosshairs).
- Elevation Turret: Located in the center on the top of your scope. This adjusts your sight up and down.
- Windage Turret: Located in the center on the right side of your scope. This adjusts your sight left and right.
- Objective Lens: The part of your rifle scope farthest away from your eye and closest to the end of your barrel.
Conclusion
The components of a rifle scope all work together to enhance the shooter's natural ability, but this will not transform a bad shot into a good shot as the old saying goes 'it's the nut behind the butt' so get out there and get shooting.