Reticles
Telescopic sights come with a variety of different reticles, ranging from the traditional crosshairs to complex reticles designed to allow the shooter to estimate accurately the range to a target, to compensate for the bullet drop, and to compensate for the windage required due to crosswinds. A user can estimate the range to objects of known size, the size of objects at known distances, and even roughly compensate for both bullet drop and wind drifts at known ranges with a reticle-equipped scope.
For example, with a typical Leupold brand duplex 16 Minute of Angle (MOA) reticle (of a type as shown in image B) on a fixed power scope, the distance from post to post (that is, between the heavy lines of the reticle spanning the center of the scope picture) is approximately 32 inches (81 centimetres) at 200 yards (180 m), or, equivalently, approximately 16 inches (41 centimetres) from the center to any post at 200 yards. If a target of a known diameter of 16 inches fills just half of the total post-to-post distance (i.e. filling from scope center to post), then the distance to target is approximately 200 yards (180 m). With a target of a diameter of 16 inches that fills the entire sight picture from post to post, the range is approximately 100 yards. Other ranges can be similarly estimated accurately in an analog fashion for known target sizes through proportionality calculations. Holdover, for estimating vertical point of aim offset required for bullet drop compensation on level terrain, and horizontal windage offset (for estimating side to side point of aim offsets required for wind effect corrections) can similarly be compensated for through using approximations based on the wind speed (from observing flags or other objects) by a trained user through using the reticle marks. The less-commonly used holdunder, used for shooting on sloping terrain, can even be estimated by an appropriately-skilled user with a reticle-equipped scope, once both the slope of the terrain and the slant range to target are known.
There are two main types of reticles:
- Wire reticles
- Etched reticles
Wire reticles are the oldest type of reticles and are made out of metal wire or thread. They are mounted in an optically appropriate position in the telescopic sight's tube. Etched reticles are images of the desired reticle layout that are etched on an optic element. This optical element (lens) with the etched reticle is then mounted in the telescopic sights tube as an integrated part of the optics chain of the sight. When backlit through the ocular, a wire reticle will reflect incoming light and not present a fully opaque (black) reticle with high contrast. An etched reticle will stay fully opaque (black) if backlit. Etched reticles are considered by most to be a more refined solution and offer greater reticle layout flexibility. Because of this, some manufacturers can provide client-designed custom reticles on special order. In the more expensive and high-end contemporary telescopic sights, etched reticles dominate the market. In cheaper telescopic sights, wire reticles are still often mounted to avoid a rather specialized and costly production step.
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