Performance Scopes

Scope Selection Tips

When I first began shooting, in my youth, I especially enjoyed the 'peep sight', or what is called a 'Flip Up Iron Sight' because it gave me a faster focus on the target. However, the drawbacks were: limited viewing area and sometimes a dead spot from the front sight. However as I progressed into the scope arena, I soon found the popular variable scopes. From this early beginning, the ability to vary my focus and target acquisition times became very important. Over the years a number of innovations, have provided a wide range of precision shooting and viewing optics. From precision variable scopes for competition shooting, along with variable spotting scopes and range finders, to red dot and laser sights, we have a very large number of options when choosing shooting optics. What I want to focus on today though, (no pun intended) is the variable rifle scope and the selection process when choosing a scope for your own shooting needs.

What do the numbers mean?
All scopes have a sizing system made up of 2-3 numbers eg: 3-9x40mm, The first number in the range tells the lowest magnification. If we use the example of a 3-9x40mm scope we would have variable magnification capable of bringing the target 3 times closer than the naked eye and up to 9 times closer than the naked eye. An important consideration in choosing a variable rifle scope is how low the magnification, not how high since the higher the magnification the less light you get through the eyepiece.

The final number is the objective lens diameter, measured in millimeters, normally ranging from 40 to 50 millimeter. Some of the extreme models go up to 75 millimeters, even though it isn't necessary for most conditions. The higher the number of the objective lens, the more light you get through your eyepiece. A fine balance exists between magnification and objective lens diameter, which determines the greatest detail, so important for accurate shooting.

Target acquisition
Choosing magnification range depends on several factors. The lower the magnification, the greater detail you will see. Also, keep in mind the target size and lighting conditions where you will be shooting. Small game or small targets, at long range, will require a greater magnification ie: 20x. However, the longer ranges will require a larger objective lens if shooting in lower light conditions, to enable more light gathering ability into the eyepiece. So, you might choose 3-9x40 scope for deer hunting, but for squirrel hunting, you might need 4-16x50mm variable rifle scope if you will be shooting targets from a longer distance. For small varmints at longer ranges a 6.5-25x56mm scope may be more appropriate. In addition, the objectives can be adjustable or variable. External parallax adjustments make it possible to adjust the diameter of variable objective hunting scopes, which can make a difference on scopes that go over 10X magnification. Scopes below that magnification will generally not have an external parralax adjustment.

Coatings and clarity
Lenses are typically waterproof, and fog-proof and are coated with single or multiple-layered coatings that help reduce glare and loss of light. Generally, the more layers of coatings-the sharper the contrast and the clearer the image will be. Fully, multi-coated scopes are generally regarded as having the best lenses since they usually mean better light transmission and sharper contrast for the user.

Field of View
Another important measurement to consider when selecting a scope is the 'field of view' (FOV). This measurement refers to how many feet left to right you can see when you are looking through the scope at any given distance. This same term applies to Spotting Scopes, Range Finders, and Binoculars. As an example, you will have about a 30 foot FOV at a 100 yard distance with 3 times magnification. Picture your view through the scope, which is a circle. If the FOV of that circle is 14 feet you have a much reduced viewing area compared with a 30 foot FOV. if you are shooting long range at fairly stationary targets then you have more time to 'find' your target, and the FOV is not as critical. However if your target is moving, then a larger diameter FOV circle is more important in order to quickly 'acquire' you target. As the magnification goes down, the Field of View goes up. At 9 times magnification, the Field of View would be approximately 14-16 feet at 100 yards. This is important when determining how quickly you can acquire your target, particularly if it is moving. Obviously, a 14 foot FOV will not provide much time to locate (acquire) a moving target compared to a 30 foot FOV.

As you can see there are more variables in scope selection than just magnification. Consider the typical shooting you will be doing with the particular caliber with the distance and lighting conditions in mind. A well researched scope will reap many rewards in varying conditions.

The author is Raymond Berg. For more information on specific optics click here: