Scope Terminology
| What do the numbers
mean? eg: 3-9x40 The first number is the magnification power of the scope, in this case it will magnify an object by a factor of 3. If the number is followed by an x this indicates that the scope is a fixed power scope. If the number is followed by an a - and a number, -9 in this case, then the scope has adjustable power. In this instance up to a factor of 9. The number after the x is the size in millimetres of the diameter of the light gathering objective lens. Adjustable Objective (AO) Adjustable focus from a set distance to infinity. Often referred to as PA (parallax adjustable) objective. Can also be found in the form of a sidewheel (sw) located on the saddle of the scope. Bullet Drop Compensation (BDC) The trajectory of all projects is in an arc, therfore the further from your target you are, the lower the point of impact will be, compared to the rifles muzzle. BDC compensates for this drop when you dial in the distance to the target. Elevation Vertical scope adjustment up and down, usually the top turret of the scope. Eye Relief The distance from the ocular lens that your eye needs to be, to see a full sight image. Lens Coatings Lenses and prisms may be described as coated, fully coated, multi coated or fully multi coated. Coated - means that some lens surfaces have been covered with a thin layer of magnesium fluoride that reduces unwanted reflections and glare, increasing light transmission and contrast. Fully Coated - means that all air to glass lens surfaces and usually the long side of the prism have been coated. Multi Coated - means that multiple layers have been applied to one or more surfaces to further reduce reflections. Fully Multi Coated - means all air to glass surfaces and sometimes the long side of the prism, have multiple layers of coatings. Minutes of Adjustment (MOA) The sensitivity of the controls on a scope is measured in MOA's. A scope with 1/4" MOA means that for every click of the adjustment the centre point of the scope moves a 1/4" when measured at 100 yards. Parallax When the shooter moves his head, parallax, a distortion of the image, can occur. This happens when the image is not focused exactly on the reticle plane. More advanced scopes have parallax adjustment (PA) to eradicate the problem. Reticle (or Reticule) This is the aiming device or cross hairs within the scope. These come in a wide variety of designs and patterns, with some even being illuminated so they are visible against dark backgrounds. |
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| Illuminated Reticle | Diamond Mag Scope Hairs | Pro-Diamond Reticle |
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| Mil Dot Reticle | M.A.P. Reticle | S.R. Reticle |
Horizontal scope adjustment left or right. Usually the side turret of the scope.
