How Rifle Scopes Work

The purpose of a scope is to make it easier for the shooter to hit the target. So, a riflescope is designed to deliver as much pure light as possible to a shooter’s eye. Light rays bouncing off the target image (in the distance downrange) are received by the objective lens at the front of the scope and are magnified. The target image comes into the scope upside down and enlarged, just like in archaic cameras. The erector lens system, in the middle portion of the scope’s main tube, magnifies and turns the upside-down image right-side up. Then, there is another lens at the rear of the scope that magnifies the target image more. This is the lens that shoots the targettarget image and the center aiming point, known as the reticle (reticule) or “crosshairs”, on to the shooter’s eye.

Parts of a Rifle Scope

A rifle scopes contains two tubes, one within the other. The inner tubes refracts light for magnification purposes, while the outer tube protects the inner tube and provides a mount for the three of the parts found in rifle scopes. All riflescopes contain about the same ten or so parts. These parts include:

  • Eye Piece: Holds the ocular lens and attaches to the eye-bell.
  • Ocular Lens: This is the through which the shooter looks.
  • Eye Bell: This holds the eye piece attached to the tube.
  • Power Ring: This allows the the shooter to change the magnification of the scope by rotation.
  • Windage Adjustment: Changes the aiming point of the scope left to right on the horizontal plane.
  • Elevation Adjustment: Shifts the aiming point up and down along the vertical plane.
  • Tube: This is the main body for the scope and provides a body for the eye piece, eye-bell and objective bell.
  • Objective Bell: This holds the objective lens (fartherest away from the shooter).
  • Objective lens: This lens collects the light as it enters the scope. The wider the field of view the larger the diameter of the objective lens.
  • Adjustable Objective Lens (AO): This rectifies parallax error by adjusting the objective lens. Parallax error occurs in a medium to high powered scope, when the scope’s “eye” is not focused at the right distance.
  • (Additionally) Eye Relief: Refers to the distance between your eye and the ocular lens when you see the full field of view. The larger the eye relief the better the riflescope.