Choosing a Rifle Scope

With there being literally thousands of rifle scopes on the market today, choosing the one that's right for you can sometimes be a confusing task. The best scope for deer hunting will not necessarily be the best scope for competition target shooting. Once you understand the various terms that manufacturers use, and understand the basics about scopes, you'll be in a better position to choose the scope that's right for you.

The Basics

The first consideration should be the quality of the glass. Unfortunately, while optical quality can be measured, there's no specifications published that will tell you which scope lenses are of better quality than others. You'll need to compare one scope to another by looking through them to judge the sharpness and contrast of the lenses. In general, you should buy the best quality scope that you can afford.

The quality of the lenses isn't entirely due to the glass itself, though. Lens coatings aid in contrast, light transmission and glare reduction, and there are terms that describe the type of coatings on a scope. A "coated" lens has a coating on the exterior surface of the lens. A "fully coated" lens has a coating on all lens surfaces exposed to the air, both front and rear. "Multi-coated" lenses have multiple layers of coatings on at least one surface of the lens. "Fully-multicoated" lenses have multiple coatings on all front and rear lens surfaces. The quality of the lens coatings can vary from manufacturer to manufacturer, or even from one model to another by the same manufacturer, so you'll want to compare the image quality of various scopes.

Another initial consideration when selecting a scope is its construction. If you anticipate using your scope in inclement weather, you'll want to make sure that the interior of the scope is filled with a substance such as nitrogen, which keeps air from getting into the scope and causing moisture condensation on the interior surfaces of the lenses. You'll also want to make sure that the scope body is weatherproof or at least weather-resistant.

Yet another factor in your selection process is the magnification of the scope. There are variable magnification scopes and fixed power scopes. A scope that's marked 3x30 will have a fixed magnification of 3 (the 30 is the lens diameter, which we'll get to shortly). A scope that's marked 3-9x30 is a variable power scope, with the magnification adjustable from 3 power to 9 power. The magnification of a scope is usually referred to with an X, as in 3X. A 3X scope will make the target appear 3 times larger than it would be with the naked eye.

How much magnification do you need? That depends upon your intended use for the scope. Those who hunt at relatively short ranges, such as deer hunters, usually will want a lower magnification such as 3X. A higher magnification would make it difficult for them to see the entire deer and would also make the field of view too narrow for them to scan the area looking for deer. Whether you need a fixed power scope or a variable power scope is your personal preference. Years ago variable power scopes were slightly inferior to fixed power scopes; that's no longer the case today. Variable power scopes also offer flexibility for different shooting situations.

Varmint hunters, benchrest shooters and other long-range shooters will often want the highest magnification they can afford. For these users, a 20, 30 or even 40X magnification isn't unusual.

There's also the light-gathering ability of the scope to consider. Generally speaking, the larger the diameter of the front ("objective") lens, the more light it gathers, which means that your target is visible at lower light levels. A 30 millimeter objective lens is fine for shooting during the daytime, but if you're planning on shooting at the break of dawn or the last light of the day, a larger objective lens will be a significant help. 40 or 50 millimeter objective lenses are the most common large objective lens sizes.

The Options

Scope manufacturers are providing a wide variety of options for specific needs. Included in these are turrets, reticle patterns, adjustable objectives, and more. Again, what you need depends upon your specific use for the scope.

The turrets are the adjustment knobs, usually located on the top and right side of the scope, that allow you to adjust the point of impact of your shot up or down and left or right. The most basic turrets are almost flush with the scope tube, and allow you to make adjustments using a screwdriver or a dime. Some of these flush turrets will have click adjustments. The flush-mounted turrets are probably the most commonly used for hunting, since most hunters don't make adjustments to their scopes once the rifle/scope combination is set for a particular distance.

Target turrets protrude from the scope body, sometimes significantly, and allow the user to make quick adjustments for windage or elevation. These are popular with benchrest shooters, varmint hunters, snipers and other long-range shooters for whom a small adjustment will make a big difference in the point of impact downrange. Target turrets usually have click adjustments in either 1/4 or 1/8 Minute of Angle (MOA). Minute of angle is an expression of the number of degrees in an arc. For example, a 1/4 minute of angle adjustment will result in a point of impact change of 1/4" at 100 yards, 1/2" at 200 yards, 1" at 400 yards, and so on.

Your choice of reticles, or "crosshairs," is now so great that it would be impossible in this article to describe all of the options. They range from fine crosshairs to thick crosshairs to illuminated reticles, and more. Each has its advantages and disadvantages. For hunting, the combination of thick crosshairs on the outside edge of the reticle and thin crosshairs in the middle seems to be the most popular. Mil-dot reticles have become increasingly popular. These have dots regularly spaced along the reticle lines, and allow the user to gauge the distance to the target. Other scopes offer even more advanced rangefinding options than mil-dot reticles.

A popular option for precision shooting is the adjustable objective lens. Scopes without adjustable objective lenses are affected by what is called parallax. Parallax is the apparent difference in position of the target relative to the reticle at different distances. With a fixed-objective scope, if you move your eye left or right the barrel is no longer pointing to the same spot on the target as the reticle. You can see this if you mount your rifle solidly and look through the scope; move your eye slightly to the left and right, and you'll see that the reticle isn't in the same position on the target. While the parallax shift may be subtle, at longer distances it can make a significant difference in the point of impact. An adjustable objective scope allows you to correct for parallax for a particular distance by either turning a ring on the front of the scope or by a turret on the side of the scope. Fixed-objective scopes are generally set to be parallax-free at 100 yards; the adjustable objective allows for more fine-tuning.

The Technicals

When you're shopping for a scope, you'll encounter all sorts of technical specifications, some more important than others.

Eye relief is an important technical consideration. This is the distance from your eye to the rear ("ocular") lens at which you can see the full target picture. The eye relief measurement will determine where on your rifle you'll be mounting your scope. If the amount of eye relief is too short or too long, you won't be able to properly position your cheek on the stock.

Field of view is another important factor. Field of view is the amount of area you're able to view at a particular distance, usually measured in feet at 100 yards. For example, with a 3 power scope you would be able to view roughly 30 feet of terrain from left to right at 100 yards. The field of view becomes smaller as the magnification of the scope increases. Hunters typically prefer a wide field of view, while precision shooters usually want to narrow in on the target.

You'll often see "Exit Pupil" as one of the technical specifications on a scope. This is the size of the circle of light on the rear ("ocular") lens that is visible to you from arms length, and is usually expressed in millimeters. The size of the exit pupil is a factor of the magnification of the scope and the size of the objective lens. On high magnification scopes the exit pupil size can become so small that your eye must be directly in line with the scope in order to see the entire circle of view.

Technical specifications will often include the adjustment range of the scope, usually measured at 100 yards. Adjustment ranges vary from as little as 25 inches to as much as 150 inches or more. If you use your scope at moderate distances, and your scope has been properly mounted so that it's on target at the middle of the adjustment range, a smaller adjustment range isn't generally a concern. However, for long-distance shooters a wide adjustment range is a necessity, as bullet drops begin to be measured in feet rather than inches.

An often-overlooked technical specification is the mounting length. If the mounting length of the scope is too long or too short, you may not be able to put the mounting rings in the proper spots on your rifle, or you may wind up having to get a special scope mount.

With advances in technology, there's almost no such thing as a bad scope today. Even the least expensive models give better performance than scopes made decades ago. But, when you consider that you may be using the scope you buy for years to come, it's a good idea to get the best model you can afford that suits your particular needs.