Illustrated Guide to Choosing the Right Rifle Scope

Rifle Scope Objective LensHunters will often say, “get the best scope you can afford.”  This is true in theory, but spending more money doesn’t necessarily mean you are getting the best scope for your needs.  Scope features have advantages and drawbacks depending on how you use them.

The key to finding the right scope with the best features is to consider the way you will use it.  Before we explain scope features, let’s cover some of the things you should think about when buying a scope.

How You Will Use Your Rifle Scope?

The range you you be shooting is the biggest factor in selecting a scope.  You will want to consider a more powerful scope and enhanced reticules for long-range shooting.  On the other hand, many hunters will never shoot at a range that requires advanced features like parallax adjustment.

What rifle will you be using?  Not all scopes are interchangeable with every gun.  For example, the configuration and power of a rifle are considerations for eye relief and mounting, air rifles have two-way recoil that can damage some scopes and, scopes with BDC are built for use with a particular caliber or cartridge.

The size of your game and its habit can influence the ideal field of view (objective size) as well as the precision needed.

If you will be moving a lot, weight or bulk may be a consideration.  Likewise, you may want to the ability to quickly reset your zero or lock it in place depending on the answer to this question.

Major Rifle Scope Parts

What Do the Numbers On a Rifle Scope Mean?

Most often rifle scopes will be referenced by a series of numbers, such as 3-9×40, 5-25×56, 1-6×24 or even just 3×30.  These refer to power and objective.

  • Power. The first number in the series, located before the x, refers to magnification. The higher the number, the higher the power of magnification the scope provides. When using a scope with a first number of 10, you will see an image ten times what the naked eye sees. If you are using a variable scope, you will see a range of numbers before the x.
  • Objective. The number that follows the x in the series refers to the diameter of the objective lens. The objective lens is the lens that is opposite the lens you look through. Larger objective lenses are bulkier, but they offer a larger field of view. A larger objective lens also allows more light to enter the scope which creates a clearer sight picture, especially under low light conditions.

Taking 3-9×40 for example; the 3-9x refers to the range of power (magnification), which is adjustable to between 3x and 9x the distance and clarity of your regular vision.

The 40 refers to the objective diameter, which in basic terms means the size of the lens (in millimeters) on the end of the scope pointed at the target.  This determines your field of view when looking through the scope and can also impact light capture.

Here we look at each of the different features in detail and how to choose the best configuration for your hunting needs.

Selecting the Best Scope Magnification

Scopes come in either an adjustable format, or a fixed power. You can be forgiven for thinking “the more power, the better” however this is not necessarily the case. Generally, when it comes to hunting, it is best to keep the scope at a low to medium magnification.  Zooming in too far can restrict your field of view and make it more difficult to quickly and efficiently locate your target.

  • Fixed power (between 1x and 6x): Best used for hunting when your distances are not changing often. It also helps to keep your shots consistent and build familiarity with the scope and rifle. Fixed scopes can also come in larger than 6x magnification, but are less ideal for hunting as it may be too magnified to effectively locate an animal that comes in close.
  • Low magnification (between 1x and 10x): Best for most hunting applications. A 3-9x scope is pretty standard and provides the ability to effectively adjust between in-close shots and those out to a few hundred yards.
  • High magnification (12x and greater): Used mostly for longer-range shooting. To best utilize these magnifications and distances, a high level of proficiency and a steady shooting rest is required. This power is less common in most forms of hunting.

How to Choose Scope Objective Lens Diameter

The objective lens diameter is greatest contributor to the physical size and weight of your scope. For most purposes you will want to find a balance between field-of-view (which also considers light intake during low-light conditions), and weight/practicality.Objective Lens Field of Vision

  • Small diameter (under 28mm): These are not usually used in hunting.  They are best in conjunction with low powered scopes, a smaller caliber rifle and close-range shooting. They are lighter weight and don’t take up much space.
  • Medium diameter (between 30 and 44mm): This is the best range for most hunting applications.  They can be reasonably lightweight, but allows for good field of view and effectiveness under low light conditions.
  • Large diameter (greater than 50mm): Best used for long-range shooting, in conjunction with high magnification.  Large diameter scopes also work best in low light conditions, but they are noticeably heavier than other scopes and can amplify glare in bright conditions.

How to Choose a Scope Reticule

Often described as the “crosshairs” of the scope, reticules come in almost unlimited configurations.  As a whole can be categorized by these key groups:Reticle Examples

  • Duplex: These reticles can be described as a basic crosshair-style.  They are easy and often the best choice for short or medium distances.  They generally come unmarked apart from a key horizontal line and a vertical line, converging in the middle.  Duplex reticules will be accurate up to 200 yards for most common big game calibers using just the reticle centerpoint.
  • BDC: This refers to “bullet drop compensator”, which will have marks below the centerpoint of the reticle in order to factor in bullet drop over distance.  For example; if the centrepoint is for a rifle zeroed at 100 yards, the marks below it may relate to 200 yards, 300 yards, 400 yards and so forth. This allows for easy calculation and target acquisition while hunting at long distance.  It is important to note that BDC reticules are designed for a particular cartridge so they are not interchangeable across calibers.
  • MOA: “Minute of angle” reticles are primarily for longer range shooting.  The markings allow you to account for factors such as distance, topography and windage.  They require the shooter to make calculations and are best for those with greater experience.
  • Mil-Dot: Similar in structure and premise to the MOA, the “milliradian” uses a different scale of measurement, but functions primarily in the same way.

Reticle Focal Point

There are two types of rifle scopes. What is FFP and SFP?  The acronyms refer to the reticle size in relation to the magnification.

  • First Focal Plane (FFP) – FFP scopes adjust reticle size based on magnification.  By doing this, the reticle stays in at a constant scale in comparison to the target.  This can allow for more precise long-range targeting.  The trade-off is that sometimes the reticle is harder to pick up at lower magnifications.  FFPs are excellent for long-range shooting but may not be as versatile as SFPs and they are usually more expensive.
  • Second Focal Plane (SFP) – The reticle in SFP sights do not change regardless of the magnification.  This means that the reticle becomes larger compared to the target as magnification increases.  At long distances this can cause the scope to be less precise.  Nevertheless, SFP is the most common and most versatile type of scope.


Illuminated scopes

Illuminated scopes have retiles that can be illuminated with an LED light.  Illumination does not refer to the brightness of the optics or nigh vision.  Illumination can help you see the reticle in low light conditions or when the color or shade of your target obscures the reticle lines.

Sometime reticles designed for illumination can be harder to see when not illuminated, so make sure you have good batteries if you have an illuminated scope.

What is Parallax Adjustment?

Parallax Adjustment puts the reticle on the same focal plane as the target so that the reticule doesn’t move around the target if the shooter’s eye moves. 

Who needs parallax Adjustment?  Most shooters and hunters will be able to make a kill shot at up to 200 yards without parallax adjustment.  If you need absolute precision or expect to be shooting at long range, then investing in parallax adjustment may make sense.

Night Vision Scopes

Night vision scopes allow you to see in low and no light conditions.  They work using either infrared light or digital image enhancement.  Although they can help you see in the dark at ranges over 1000 feet, the image clarity is not as precise as a traditional scope.  They are typically used in tactical situations rather than hunting.


What is Eye Relief?

Eye Relief DiagramEye relief is the required distance between the shooter’s eye and the lens of the scope in order to properly view the target field.  If your eye is too far from the scope, the view will be narrower with darkness around the edges.

Why does eye relief matter?  Average eye relief is 3 to 3.5 inches, but it tends to be lower with greater magnification.  Eye relief will change with magnification on adjustable power scopes.  Although more eye-relief is frequently thought of as better, the ideal distance can depend greatly on shooter preference and the configuration of the scope and rifle.Correct Eye Relief

For high-powered rifles with a lot of recoil, eye relief can also be an important safety consideration.

What is a long eye relief scope?  Long eye relief scopes have relief of six inches or more.  If a scope will be mounted forward on your rifle due to the bolt or magazine placement, then you will need greater than normal eye relief.  This is particularly common on military-style rifles.

There’ some more great information on eye relief in this article from Buckmasters.


Scope Turrets

Scope TurretsTurrets are knobs found on the scope that are used to adjust elevation (up and down) and windage (left and right) to allow the shooter to account for distance and crosswinds.  The windage turret is typically on the left side of the scope and the elevation turret sits at the top of the turret.  Scopes with parallax adjustment will also have a turret on the right sight.

What are Turret Lock and Turret Stop?

A turret lock feature will stop the turrets from being adjusted unintentionally, whereas a zero stop feature allows for a baseline zero in which you can easily return to after in the field changes.

Capped Turrets vs Exposed Turrets

Turrets can either be “capped”, where the adjustment is found underneath a cap, or “exposed” which gives instant access to adjustment in the field.Exposed and Capped Turrets

  • Capped: These are more secure and less likely to be accidentally shifted. Capped turrets are best used when you wish to “set and forget” when it comes to zeroing your rifle. If you intend on basic shooting and reasonably consistent (not too far) distances, these are fine, especially when factoring in the reticle options mentioned above.
  • Exposed: Having the turrets exposed gives the shooter the opportunity to make distance adjustments in the field depending on the distance required on the shot. As opposed to using the reticle markings, this will “re-zero” your rifle to the distance you wish to shoot, factoring in bullet drop at distance and potentially windage. This takes a greater understanding of zeroing and the scope adjustments.


Product descriptions for rifle scopes can sometimes be overly technical and overwhelming. It is important to focus primarily on the key aspects of the scope based on what you intend to use it for. Magnification and objective lens size being the primary focus, considering factors such as likely shooting distances, style of hunting and scope weight.  With some careful consideration, it is often possible to get a scope that perfectly meets your needs without breaking the bank.  Here’s our guide to the best scopes under $300.


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