|Rifle scope sights consist of a tube and crosswire sight or crosshair mounted internally and the tube is mounted on the barrel or receiver externally with scope mounts and scope rings. Rifle scopes are magnified to make targets appear closer aiding in more precise shot placement. Rifle scopes generally improve a shooters efforts in gaining the true accuracy potential of their rifle by adding some magnification to the sight picture. With a scoped rifle, sighting game is easier, quicker, and very precise simply because everything appears larger and closer due to magnification.|
Fixed power scopes:
Fixed power scopes have the magnification set by the manufacturer and can not be changed.
Variable power scopes:
On variable power scopes the magnification of the sight picture can be adjusted according to the distance of view needed by the user by simply turning the power ring at the back of the scope. A rifle scope marked as 4x-12x, is power or magnification, which means it will magnify an object from 4 times larger than you could see with the naked eye and by turning the power ring it will adjust up to 12 times larger than you could see with the naked eye.
The objective lens is the lens in the front of the scope, the larger the diameter the more light gathering ability it has. The larger the objective lens, higher scope rings are needed to allow your lens to clear the rifle barrel. A typical scope description of 4-12X44, the objective lens is 44mm.
Adjustable objective lens:
The Adjustable objective lens has the ability to correct parallax at given yardages to keep the scope on target zero for all yardages regardless of the shooters eye alignment in the scope.
Parallax is a condition that occurs when the image of the target is not focused precisely by misalignment of the shooters eye on the reticle plane. This condition exists in all scopes and accounts for more inlarging of rifle group sizes than anything else. Parallax is visible as an apparent movement between the crosshairs and the target when a shooter moves their head and changes eye alignment in the scope. The higher the magnification the more visible this is, a good high power rifle scope will have an adjustable objective lens to correct parallax at all yardages.
Exit pupil diameter:
The exit pupil diameter is the shaft of light exiting the scope toward the scope users eye, this is expressed in millimeter measurement.
Field of view:
Field of view is the measure of how much area you can see through your scope at 100 yards, generally, the higher the magnification, the less the field of view. With a field of view of 40 feet, simply means at 100 yards with a target in the center of the scope you will be able to see 20 feet to the left and 20 feet to the right of the target centered in the reticle crosshairs.
Eye relief indicates the distance between your eye and the scope, which allows you to achieve the scopes entire field of view. An eye relief of three inches is simply your eye is 3 inches from the scope and your able to see through the scope its entire field of view.