 dealers |
 my account |
 view cart |
 track order |
 wishlist |
 compare |
|
| New customer? Start here. | ||||||
| |
|
||||||||||||||
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
Want to get 5% off? |
Manufacturers 
Air Rifles
Air Pistols
Ammo
Accessories
|
Warranty |
|
Advanced Search | |
|
Scope terms and how to choose a scope
By Tom Gaylord
exclusively for PyramydAir.com. © Copyright 2005 All Rights Reserved Covered in this article: How to decode the scope model numbers When to choose high and low power Variable power Reticles - plain, duplex and mil dot Focusing a scope Parallax adjustment Scope sights are extremely popular among airgunners because good scopes wring the last bit of accuracy from a gun. They also forgive a lot of common sighting errors, as seeing the sight and target clearly at the same time is a great aid to accurate shooting. This article will explain a lot of the confusing terms used to describe scopes, plus we will look at how some of these things really work. No one scope is perfect for every job, so by understanding the terminology you can better understand which scope will best help you accomplish what you need. We will look at the common terms first, then we'll explore the types of scopes to use for different shooting situations. In the model name "4 X 32," the number four refers to the magnification power of the scope. A 4-power scope enlarges the image four times. An 8-power scope enlarges things eight times, making it seem to be closer than when seen through a 4-power scope. That sounds good, but there are drawbacks to power. The higher the magnification, the less area you can see through the scope. If your scope is too powerful, you may be able to see ants crawling on a blade of grass, but you'll never know which blade it is because they all look the same. Higher magnification also eats light. An 8-power scope will show the same image darker than a 4-power, if everything else is the same. There are ways to increase the amount of light that passes through the scope, such as larger lens diameters and even a large scope tube diameter, but if that goes too far you get a large scope that is more difficult to mount. Every lens in a scope robs a tiny bit of light that tries to pass through, so the higher the magnification, or the more lens coatings, usually the darker the image. Choose four to six power for hunting and general shooting. Nine to twelve power is good for long distance shooting and 20 power is great for paper targets that aren't going to move. The number 32 in the 4 X 32 model name refers to the diameter in millimeters of the objective lens. That's the end opposite the end you look through. The larger the objective lens, the more light that can pass through it and the brighter the image at a given magnification. As power increases, the need for light also increases; otherwise you'll be looking at a large dark shadow. That's why high-powered scopes have large objective lenses. A 4 X 32 is brighter than a 12 X 40, because the 32 mm objective lens does more for the lower-powered scope than the 40 mm lens does for the higher-powered one.
Many scopes have variable power, which is indicated in their title. Instead of a 4 X 32 scope, you might see a 4 - 12 X 32 scope. In that case, the scope's magnification is variable from four to twelve power and the objective lens is 32 mm. Take a look at some of the scopes on this site and see how easy it is to know their performance characteristics, just from these numbers in the model name.
The reticle is commonly referred to as the crosshairs. It usually consists of one vertical and one horizontal line. In the distant past, these were actual threads of silk or spider webs, but today they are more often either thin metal wires or even lines etched on glass. They are housed in a tube called the erector tube and the adjustment knobs move this tube in the desired direction. That's why the reticle lines appear centered on nearly all scopes. A few scopes from Europe have reticles that actually move in your field of view when they are adjusted, but most shooters prefer reticles that are always centered.
To determine range with a mil dot reticle requires the use of an algebraic formula that most shooters either don't know or don't care to do, but the dot reticle is still quite valuable. As the shooter becomes familiar with the reticle over time, he will develop a sense of how to best use the dots. Most shooters use the dots on the horizontal line as alternate aim points for windy situations. When you focus a scope, you aren't making the target appear sharper like you might think. Focusing means adjusting the eyepiece to get the reticle lines as sharp as possible. You normally only focus a scope one time and leave it that way unless something happens to change the focus.
Some scopes have a diopter indicator on the focus ring. Once the scope is focused, it shouldn't need changing unless the shooter's eyes change, so a prudent shooter remembers where the ring is set (if there are markings). That allows the shooter to refocus the scope by adjusting the ring back to the mark rather than going through the whole focusing process again. Don't confuse parallax adjustment with focusing the scope. When parallax is adjusted, it cancels as much parallax as possible between the reticle and the target to give you the best possible chance of hitting the target. Now - what the heck is parallax? Parallax is the term that describes the difference in angles between objects that are seen up close and those seen far away. When you look at telephone poles pass by on the side of the road, those closest to your car seem to pass very fast, while the ones far away seem to go very slow. That difference is due to parallax.
To use a parallax ring, which many scope manufacturers call an AO (for adjustable objective) ring, turn the ring until the target appears sharp in the scope. The true distance to the target may not always agree with the numbers etched on the parallax ring of the scope, but the scope is adjusted when the image is at its sharpest. Some newer scopes now have the parallax ring on the turret with the windage and elevation knobs. It works the same way; the only difference is the location. Choosing a scope is not easy for anyone. There always seems to be another model that has some features you also want, but can't get on the model you select. That's because a scope is full of compromises. If you can afford one, buy a variable-power scope every time. On low power it will be bright and on high power it is easier to see a well-lit target. Hunters need less power than target shooters. Live targets move and a wide field of view is important if you want to see them through a scope. Low-powered scopes have the widest field of view. A 4-12 power scope is just about ideal. If you have a powerful spring air rifle, get a scope that can take the two-way recoil. And get a scope mount that has a positive recoil stop to prevent slippage. No clamping mount will hold up to sustained recoil. Make certain the scope you choose can be mounted to your airgun with the scope mounts you intend using. Spring guns are often touchy about scope clearance. If you aren't sure which reticle to select, remember that it's hard to go wrong with a duplex. The rest of scope selection will come as you gain experience with what is available. Since no one scope can do everything, the best choice is the features you know you need. Next part:All about scopes. Part 2. Mounting a scope is easy! Four easy steps to scoping an air rifle. |
| Home | Air Guns | Airsoft | SlingShots | Manufacturers | Warranty | View Shopping Cart | Blog | Pyramyd Air Waves | Airsoft Guns | Walther Airguns | More on airguns | |
| © 1999-2009 Pyramyd Air. All other designated trademarks, copyrights, and brands are the property of their respective owners. |
