Rifle Scope Glossary of Terms

Adjustable Objective

That term means nothing by itself, but since the earliest parallax adjusting scopes put the adjustment feature into the ro-tating objective bell of the scope, the term AO appeared. An adjustable objective is a dial around the objective end of the scope that allows you to adjust your scope parallax to a certain distance by moving these adjustments until a clear picture is perceived. The correct setting of an adjustable objective helps to prevent a change between the reticle and the target when the shooter moves his head off-center of the rifle scope.

Airgun Scope

We all know that powerful spring-piston airgun recoil can destroy non-airgun rated scopes in only a couple of shots. That's why airgun scopes were invented: to withstand the dual-recoil of spring-piston airguns.

Accu-Range

- is one of the most common ballistic reticles and is considered to be the basic one. It is a development of the Redfield company and has an operating range of 500 yards.

ASV + Elevationb

is a ballistic turret technology developed and owned by the optics brand Carl Zeiss.

Ballistic Plex

- This name refers to a duplex-style ballistic mesh from Burris.

Ballistic Programs

are programs or online services with specific tools that are used to calculate holdover values. Thanks to them, riflescope users can define holdover values for scopes and cartridges. The use of such programs often requires certain knowledge and additional information, for example, bullet ratio, sea level, and wind speed.

Ballistic Reticle

is a reticle that includes various factors to ensure the correct aiming point. They are used to increase the range of an aimed shot and predict the bullet's flight at an angle. Ballistic reticles use BDC technology to correlate angles, atmospheric conditions, ammunition data, and angles. Ballistic reticles come in different flavors, with different designs, densities, and different stage lines and crosshair heights.

Ballistic Turret

is a feature common to expensive and high-end riflescopes. It allows you to set several preset distances. This eliminates the uncertainty in the distance estimation and eliminates the need for ballistic reticles.

Ballistic X

is the standard Weaver's Ballistic Reticle.

BAS

- Leupold Ballistic Aiming System. It includes integrated ballistic reticles and ballistic turrets, designed for accurate targeting, regardless of the weapon's conditions.

BDC

- Bullet Drop Compensation. The principle of interaction between the indicators of the fired bullet, gravity, and target.

The BRX / BRX

Heavy are Swarovski ballistic rejects designed for long-range hunting rifles.

Centerfire

- is a concept that is relevant to all cartridges, including shot, hand, and rifle weapons. Indicates the point at which the weapon striker hits the bullet base becomes the catalyst that triggers the chain of events that lead to the shot.

Clicks

- is a simple word that, among other things, means the number of revolutions of the turrets, which allow you to aim and make adjustments to the shooting.

Coatings

are a special chemical coating that is applied to the lenses of optical devices to eliminate glare. The better and more such a coating is applied by the manufacturer, the better and clearer the observer's image.

CRS Zero Stop

- configurable rotation stop.

DDB

- is an acronym for Bushnell's Dusk & Dawn Brightness Multi-Coating Formula for scope lenses.

DOA

- Bushnell's Dead On Accurate Ballistic Reticle.

Dovetail

is a specific design groove pattern where the base is wider than the top for setting and securing rings and bases. It was named so because of its external similarity with the tail of a dove.

Dual X

is a double ballistic net from Weaver.

Exit Pupil

Exit pupil is a significant factor in light transmission of an optic and is generally ignored or misunderstood by many people. It controls the brightness of the image that will be viewable to your eye. It is visible in the eye lens when you hold the scope at arm's length.

Eye relief

Eye Relief is a space that affects how full you'll see the view of the scope. Typical scopes offer around 2 ½ - 3” eye relief.

Field of View

Field of view is an actual image that you see when you look through your scope. The distance from one edge of the circle to the other is the field of view. If you have set it wrong for your eyes, you could see a fuzzy black edge t closing the view.

Fast Focus Eyepiece

is a European style eyepiece technology with a fraction of a turn focal length. It allows you to focus on the grid, which gives you a sharp and clear image. At the same time, the focusing speed is higher in comparison with the standard method. Oftentimes, however, the Fast Focus Eyepiece does not have a locking mechanism for the slower meth-od.

FFP

- an indication of the first (focal) plane to the position of the reticle. FFP scopes retain the amount of stretch, while the size of the crosshair of the sight will correlate with the image's magnification.

Fixed Power

- denotes a fixed magnification of the sight. It does not have a range of power settings from low to high, as the manufacturer sets a constant increase within a certain scaling.

Kentucky Windage

Kentucky windage is the point that helps you to set for wind effects on your projectile. It allows you not to reset your scope.

Magnification

You'd see something with the naked eye differently—a wide field of view and a lot of things around. Magnification helps to narrow the field of view. Magnification is the size of an image relative to the size of the object creating it.

Maximum Point Blank Zero

Blank zero is the elevation and windage settings required to engage a point target from zero to your max point-blank range under ideal weather conditions. To find the max point-blank range, you should consider the ballistic coefficient of the round, the muzzle velocity, and the gun's sight height. This is good for guns that have higher sights or optics that don't have an elevation compensator.

Muzzle

The muzzle is the front end of the barrel from which the bullet exits.

Minute of Angle

A minute is just a fancy word for one-sixtieth (think about 60 minutes in an hour). Well, that's the same as saying one mi-nute is a sixtieth of an hour. This minute is gonna be the sixtieth of the angle that is on the circle of 360 degrees. So, the sixtieth of one of those degrees is one minute of angle. It ends being about 1.0400 inches at 100 yards.

It's not a size at a certain distance, but rather it's an angle that we're making in the scope that ends up translating to a cer-tain size at a certain distance.

Objective Lens

The objective lens is one of the most important parts of the optical system. An objective lens is the lens closest to the ob-ject being viewed. It usually has a lot of numbers, and letters but not every person knows what they mean. A first number is a whole number (magnification of an objective). The next number is a decimal number that means a numerical aperture for the lens's light-gathering ability. It is measured in millimeters in diameter.

Ocular Lens

An ocular lens is a lens that is closest to your eye.

Parallax

Parallax is the apparent setting of the reticle on the target image at different ranges. When we are shooting, we deal with three different planes (the eye, inside of the rifle scope, and the target). Parallax errors start to come into play when your head and eye start to move off-axis a little bit over to one side.

Reticle

A reticle is a system of lines, dots, or crosshairs in your scope that appear superimposed on your target. The most common design you'll see is a rear focal plane or second focal plane design. It is placed behind the magnification adjustment that means when you change your magnification, grow the size of your target, or shrink your target's size, your reticle size never changes and always stays the same size.

The front or first focal plane does the opposite. It puts the reticle in front of the magnification adjustment. So when you grow your magnification, not only does your target size get bigger or smaller, your reticle size gets bigger or smaller in the same way.

Trajectory

The trajectory is a path of the body as it travels through space, or to be more clear. It's the flight of your bullet after it leaves the barrel.

Twilight Factor

Twilight Factor is a geometrical calculation of how bright a particular optical product is. It basically means a square root of the multiplication of magnification and objective lens diameter. The twilight factor helps to compare different optics and determine which one will be better in low light. A twilight factor was important to determine which optics will perform better in low light, but nowadays there geometrical calculations are used instead.