Understanding rifle scope terminologies are crucial for both beginner and experienced shooters. It enhances your knowledge of how scopes function and aids in making informed decisions when selecting or using a rifle scope. Here are the top 20 terms you need to know:
Adjustable Objective (AO): Allows you to adjust the scope’s parallax for a clear picture at various distances.
Airgun Scope: Designed to withstand the dual-recoil impulse of spring piston airguns, often with adjustable objectives for short distances.
Ballistic Coefficient (BC):A measure of bullet performance. Higher BC bullets retain more velocity downrange. This means that a bullet with a higher BC will have a flatter trajectory and less wind drift.
Index Click / Turret Click: One adjustment notch on the windage or elevation turret, usually changing the point of impact by 1/4 inch at 100 yards.
Coatings: Extremely thin layers on lens surfaces to reduce light loss and glare, enhancing image brightness and contrast.
Diopter Focus: Focus mechanism on the eyepiece, used to bring the reticle into focus for the individual user’s eye.
Exit Pupil: The diameter of the light beam visible in the ocular lens, influencing image brightness.
Eye Relief: The distance from the ocular lens to your eye for a full field of view.
Field of View (FOV): The area visible through the scope from right to left at a specific distance.
Magnification: The power rating of the scope, indicating how much closer objects appear compared to the naked eye.
Minute of Angle (MOA): A unit of measurement of a circle, roughly equating to 1 inch at 100 yards.
Objective Lens: The lens closest to the object being viewed, measured in millimeters.
Ocular Lens: The lens closest to your eye.
Parallax / Parallax Error: The apparent position shift of the reticle on the target at different ranges.
Reticle: A system of lines or crosshairs in your scope superimposed on your target.
Turret: Precision dials on the scope for adjusting elevation and windage.
Twilight Factor: A measurement of scope efficiency in low light conditions.
Zero: The distance at which your bullet impact precisely matches the point of aim, usually in the centre of the reticle. For most shooters and hunters using centrefire rifles, this distance is typically 100 yards or 100 metres.
Front (First) Focal Plane Reticles: Reticles located in front of the magnification system, reticle always remains in calibration to the target, regardless of the magnifications setting.
Rear (Second) Focal Plane Reticles: Reticles located behind the magnification system, reticle calibration is true only at a specified magnification setting (usually the highest magnification power). To the shooter, the perceived size of the reticle will appear to remain constant regardless of magnification changes.
Understanding these terms will enhance your shooting experience, whether you’re a hunter, sports shooter, or tactical enthusiast. Each term plays a significant role in the functionality and performance of a rifle scope, and knowledge of these terms ensures you make the best use of your optical equipment.