Riflescope Short Course  

Riflescopes  

A riflescope indicates a bullet’s point of impact and makes distant targets and surrounding objects appear closer. A riflescope is recommended for safer, more accurate shooting in the field and on the range. 

Diagram of a riflescope 

 Coated Optics
Coatings on lens surfaces reduce light loss and glare due to reflection for a brighter, higher-contrast image with reduced eyestrain. More coatings lead to better light transmission.

Types of Coating
Coated – A single layer on at least one lens surface.
Fully Coated – A single layer on all air-to-glass surfaces.
Multi-Coated – Multiple layers on at least one lens surface.
Fully Multi-Coated – Multiple layers on all air-to-glass surfaces.

Exit Pupil
The size of the column of light that leaves the eyepiece of a scope. The larger the exit pupil, the brighter the image. To determine the size, divide the objective lens diameter by the power (a 4x32 model has an exit pupil of 8mm).

Eye Relief
The distance a scope can be held away from the eye and still present the full field-of-view.  

Field-of-View (F.O.V.)
The side-to-side measurement of the circular viewing field or subject area. It is defined by the width in feet or meters of the area visible at 100 yards or meters. A wide field-of-view makes it easier to spot game and track moving targets. Generally, the higher the magnification, the narrower the field-of-view.

Magnification (Power)
Riflescopes are often referred to by two numbers separated by an "x". For example: 4x32. The first number is the power or magnification of the scope. With a "4x", the object being viewed appears to be four times closer than when seen with the unaided eye.

Objective Lens Size
The second number in the formula (4x32) is the diameter of the objective or front lens in millimeters. The larger the objective lens, the more light that enters the scope, and the brighter the image.

Ocular Lens
The lens closest to your eye.

Parallax
A condition that occurs when the image of the target is not focused precisely on the reticle plane. Parallax is visible as an apparent movement between the reticle and the target when the shooter moves their head or, in extreme cases, as an out-of-focus image.  

Precision Adjustments
The windage and elevation adjustments affect accuracy. Windage is the horizontal (left-to-right) adjustment, usually the side turret of the scope. Elevation is the vertical (up-and-down) adjustment, usually the top turret of the scope.


Resolution
Resolution, or definition, is the ability of a scope to distinguish fine detail and retain clarity.


How to Choose
A quality riflescope is the key to a successful day at the range or in the field. Riflescopes bring distant targets and surrounding objects up close and personal allowing safer, more accurate shooting. They gather and utilize available light making it possible to shoot in lower light conditions and allowing the hunter to hunt from dawn to dusk. 

Pairing just the right riflescope with your gun and ammunition will help you get the most out of each and every shot. Selecting the correct scope to fit your needs involves a number of considerations from mechanics and construction to image quality and magnification. Keep in mind when and where you shoot most often and choose a riflescope with features that best fit the requirements of your particular sport. 

Mechanics
The inner workings of a scope have a direct effect on shooting accuracy. As adjustments are made during sight-in, the cam tube, which holds the reticle and lenses in place, moves inside the scope. To stay on target and produce a quality image, this tube must be strong enough to absorb the impact of heavy recoil during shooting and remain in place. When selecting your riflescope look for precision (positive) adjustments, point-of-impact consistency, reticle strength and waterproof, fogproof and shockproof durability. You'll also want to consider weight, bulk and ergonomics, which are especially important during long days in the field. 

Image Quality
For optimum image quality, it is important that the optical system of a riflescope deliver as much light as possible to the eye of the shooter. The lighter or brighter the image, the sharper the resolution and the clearer the shot. The quality of the glass, lens design and optical coatings all contribute to a riflescope's ability to manage light effectively. When selecting your scope, consider magnification, objective lens size, exit pupil, resolution, field-of-view and eye relief. 

Magnification
Choose a riflescope with the magnification or power that is appropriate for your particular application. 

Low Power – (examples: 1.5–6x32, 2–7x32) These riflescopes are ideal at close range and for shooting moving targets. They provide the most effective light management and produce a brighter sight picture and wider field-of-view – even in low-light conditions and thick brush. 

Medium Power – (examples: 3–9x40, 2.5–10x50) Select these riflescopes for hunting big game at medium range. 

High Power – (example: 6–18x40, 6–24x40) These riflescopes are best for target shooting, when the target is motionless and for varmints and other small game. 

Reticles
A reticle is the crosshair or pattern placed in the eyepiece of the scope which establishes the gun’s position on the target.