RIFLESCOPE 101: Everything You Need to Know About Rifle Scopes For Hunting

First-time rifle owners may find it a daunting task to sort out just what goes into making a rifle scope work.

In actuality, a rifle scope is basically a kind of telescope, complete with an objective lens and an ocular lens. The objective lens is located at the far end of the scope. The ocular lens is located at the eyepiece. Light travelling through the objective lens is focused to the ocular lens. Within the scope are focal planes that aid in this process.


When shopping for a scope, you will inevitably come across some terms in the description. Familiarity with these terms and what they mean is essential for choosing the right scope for the right rifle and usage.

For instance, you’ll often see a set of numbers indicating magnification. Say the magnification is 5-12×42. The first set of numbers indicates the range of magnification. The scope in this example will magnify the image anywhere from five to twelve times. For more experienced shooters, 5 red dot sights will also increase accuracy.

The second number indicates the size of the lens in millimeters. In this case, 42.
It is important to note that in shifting magnification settings, the shooter may have to deal with the issue of parallax.

Photo by James DeMers


Close one eye and look at a single image. Now open that eye and immediately close the other. Notice how the image seems to shift slightly within your field of vision? This is called parallax.

In rifle scope technology, parallax refers to the apparent shift in a focal point when one switches between magnification settings. At very high magnification levels, this can present what is known as a “parallax error”.

Because parallax error occurs at these high levels, not all shooters will need to contend with the problem. However, many scopes are designed to correct for this error should the need arise. The trs-25 riflescope is actually a parallax free layout where the dot follows the motion of the user’s eye when remaining fixed on the target.


Other issues in targeting come up frequently. The average rifle enthusiast will no doubt be familiar with windage and elevation. These are just fancy words for the horizontal and vertical alignments, respectively. The knobs for these adjustments are located on the top and side of the scope, usually near the middle of the body, or “tube”.

A little knowledge goes a long way, as the saying goes. Armed with the basic principles and terminology, anyone should be able to choose the right scope for the right job.

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