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Optics 101

Intro to optics

As a major retailer of firearms and firearm equipment, Gander Mountain offers one of the largest selections of optical equipment designed to make the outdoor experience more successful and more enjoyable. We offer a wide range of riflescopes with choices to match your gun and hunting environment. Plus our selection of scope rings and bases will help you achieve just the right setup.


We sell a great array of binoculars and spotting scopes for everything from bird watching to hunting and boating. Whether you're tracking game or checking the distance to the pin, we offer a variety of rangefinders that are sure to meet your needs. For precision in shooting and tactical equipment, you'll find we have a great selection of red dot sights, laser sights, and even night vision optics.


Gander Mountain has your optical needs covered – not just with products, but also with expert advice. This Optics 101 guide is provided to help you sort through some of the technical aspects and terminology associated with optical equipment. We hope it will be beneficial as you begin your search for the right gear.

Types of Optics

Riflescopes
Rifle Scopes

Almost all firearms have some kind of sighting device. Whether the gun is equipped with iron rear and front sights or a more powerful scope, you need help in lining up a target. The benefits of using a scope are the simplicity of aiming and the reduced strain to your eyes. Lining up your target through iron sights means you have to focus on the rear sight, the front sight, and your target, which is often frustrating and sometimes impossible for older eyes. With a scope, you just line up the crosshairs or reticle with your target. Most riflescopes also magnify your target so it appears closer and is much easier to see. The result is a precise shot and a much better chance of hitting your target. People with impaired vision are also able to adjust the focus at the ocular or eyepiece, so they get a clearer view of what they're aiming at.


Scopes are classified by their magnification and objective lens diameter. A 9x40 scope has a magnification or power of 9. This means the object will appear 9 times closer than it does with the naked eye. 40 is the objective lens diameter in millimeters; this lets you know the amount of light let in by the lens in order to form a clear image. A 3-9x40 scope is a variable scope that lets you adjust the magnification from 3x up to 9x and anywhere in between.


Field of view (FOV ) is the width of the view seen through your scope at a specified distance, usually 100 yds. As magnification on the scope increases the field of view decreases. As the magnification decreases, the field of view increases. Note that field of view is directly related to the design of the eyepiece and is not affected by objective diameter.


LIGHT TRANSMISSION is the amount of light transmitted through the lens to your eye. The best a scope can do is 98% light transmission, which is only found in the finest, most expensive scopes. 95% is excellent, while most scopes are around 90% light transmission. One thing to keep in mind is that the higher the magnification, the less light you get, and the larger the objective lens, the more light you get.


The small beam of light formed by the objective lens and appearing in the eyepiece is the exit pupil. It's measured in millimeters and can be determined by dividing the objective lens diameter by the magnification. A 3-9x40 scope when set to 3x will have a 40 divided by 3 or 13.3mm exit pupil, large enough for most low light situations. When set to 9x, the exit pupil will be 40 divided by 9 or 4.44mm, limiting the amount of available light. A larger exit pupil makes it easier to place the eye where it can receive the light. This means the image can be found quickly which is important when aiming at game. A narrow or small exit pupil may cause more fatigue because the sight must be held exactly in place in front of the eye to provide a useful image.


Eye relief is the distance from the rear eyepiece lens to the point where the eye must be positioned to see a clear, unobstructed image. Most scopes have an eye relief ranging from about 25mm (1") to 100mm (3.9"). Scopes on scout rifles are mounted in front of the receiver and need 9"-12" of eye relief for a clear view; pistol scopes used on handguns may have an eye relief up to 20". Riflescopes with a relatively long eye relief (3"-3.5" ) are preferred for avoiding injuries that may occur from recoil. Eyeglass wearers typically set up further from the eyepiece, which means they need a longer eye relief to see the entire field of view.


Lens Coatings
Most scopes are fogproof and waterproof and have coated lenses. Coatings are added to reduce glare and loss of light caused by reflection. More coatings usually lead to better light transmission and sharper images. Coatings vary in type and quality. The following terms are generally used in reference to lens coatings:


Coated – A single layer on at least one lens surface.
Fully Coated – A single layer on all "air to glass" surfaces.
Multicoated – Multiple layers on at least one lens surface.
Fully Multicoated – Multiple layers on all "air to glass" surfaces.


Also note that many optics have additional coatings that help shed water for clearer views in rain or mist.


Reticles
A reticle is the set of fine lines or crosshairs in the eyepiece of a scope used for aiming. There are many different patterns used, ranging from traditional crosshairs to more complex reticles which allow the shooter to estimate range and compensations. All are designed to give you a central aiming point. Fine crosshairs cover up a smaller amount of your target and allow you to adjust your shot in precise increments. However, fine crosshairs often get lost on a busy background or in low light. For this reason, most hunters use a thicker reticle that shows up better against foliage and helps you to focus toward the center. Fine crosshairs are best used on clean paper targets.


In a riflescope, the reticle can be located in either the first or second focal plane. On most American scopes, the reticle is in the second focal plane (SFP). In these scopes, when you increase the magnification, the reticle appears to stay the same size while the target grows larger. This means that as the target is magnified, less of it is covered by the reticle. On scopes with reticles in the first focal plane (FFP), as the magnification increases, so does the size of the crosshairs. This means the amount of the target covered by the reticle stays the same.


Some reticles, such as the Mil-Dot Reticle, can be used to calculate distance. These reticles are most often used in scopes on "tactical" or military sniper rifles. The "mil" stands for milliradian, a unit of measure that's about 3.6" at 100 yds. In other words, the dot in a Mil-Dot reticle covers 3.6" at 100 yards, 7.2" at 200 yards, and 18" at 500 yards. To calculate distance, you'll need to know the size of your target. Multiply the height of the target in yards by 1000 and divide by the number of mils. Example: A 2 yd. (6') target that covers 4 mil-dots = 2 x 1000 / 4 = a distance of 500 yds.


Because of the lack of precision and calculations required when using a Mil-Dot reticle, many shooters opt for a laser rangefinder which is quicker and much more accurate. Also Mil-Dot reticles cover more of your target than other reticles.


Illuminated Reticles are now offered on many scopes in order to keep your crosshairs visible in low light. Illumination should be adjustable to prevent glare from interfering with vision. Most illuminated reticles are red which impedes night vision the least.


Parallax
Parallax is an effect whereby the position of the object appears to change when viewed from different positions through the eyepiece. This occurs in scopes due to the objective lens and the reticle being on different planes. When the eye is placed at different points behind the ocular, it causes the crosshairs to appear at different points on the target and can cause you to miss your target at a distance for which the scope was not parallax adjusted.


To compensate for parallax, external adjustments are added to scopes of more than 10x power or scopes that are used at close distances. Two methods are generally used to make parallax corrections. The adjustable objective (usually called AO or A/O models) makes the objective lens adjustable to compensate for the error. Settings on AO models are generally read from the top of the scope. The second type is often called a side focus or sidewheel model. It uses an internal lens in the optical group mounted in front of the reticle plane that can be adjusted to correct parallax errors. The sidewheel models are more convenient since the setting can be read on the side with minimal head movement.


The parallax compensation on most scopes has been set by manufacturers at a distance that best matches the intended usage. For this reason, most scopes perform very acceptably without adjustable compensation. Generally parallax on hunting riflescopes is set to 100 or 150 yds. to make them suited for shots that rarely exceed 300 yds. Rimfire scopes are usually set at 50 yds., and shotgun scopes at 60 or 75 yds. Airgun scopes use higher power even for 10m (33') competition distances. At this short range, parallax error becomes more noticeable, so scopes for airguns most often include parallax adjustment.


Scope Adjustments and MOA
Scopes can have several different adjustment controls including:

1) Focus control – Located at the ocular end of the sight, it helps obtain a sharp picture of the object and reticle.

2) Zero-stop elevation control – Set to prevent inadvertently dialing the adjustment knob below the primary zero.

3) Windage or horizontal adjustment control of the reticle

4) Magnification control – Changes the magnification by turning a ring marked with power levels.

5) Illumination adjustment control – Changes the brightness level of the lit parts of the reticle crosshairs.

6) Parallax compensation control


Elevation and windage or horizontal adjustments are made in MOA or minutes of angle. This refers to a unit of measure within a circle equal to 1/60 of 1° of a circle. One minute of angle translates to 1.0472" at 100 yds. This is usually rounded to 1" at 100 yds. and therefore 2" at 200 yds., 5" at 500 yds., and so on. Turrets on most scopes will turn one "click" for each 1/4 MOA. So one click will equal 1/4" at 100 yds., 1/2" at 200 yds., or 1/8" at 50 yds. Example: If your shot lands 3" low at 100 yds. and you have a 1/4 MOA adjustment, you'll need to adjust your elevation dial up 12 clicks.


Bullet Drop Compensation (BDC)
Some scopes offer Bullet Drop Compensation (BDC), which compensates for the effect of gravity on a bullet when shot at a given distance. The BDC must be tuned to the specific trajectory of a combination of gun and cartridge at a predefined muzzle velocity and air density. Advances in technology have made the use of BDC more accessible allowing hunters accuracy on longer shots without guessing about external factors. Several manufacturers have programs and websites that provide the trajectory information needed to line up BDC reticle circles at any magnification.


Choosing A Riflescope
When choosing a riflescope, it's best to know your intended targets. You do not need as much magnification for hunting deer at no more than a 100 yards than you do for shooting long range targets. A 3-9x scope for hunting deer is just fine. The 3x will offer enough exit pupil and field of view for close shots, while the 9x provides plenty of magnification for longer shots. Don't make the mistake of using a scope with higher magnification than needed. Higher magnifications lessen your exit pupil and available light, and your field of view is often too small to find your target. So the end result might be that your view is too dark or that you can't find your prey.


In Western states and on the plains or in open country, a higher magnification range such as 4-12x works well, since your vision is not confined by woods and you're able to see the surrounding terrain more easily. For long range target shooting, a 6-20x or 8-25x high-power scope might be preferable. If you prefer less moving parts and more simplicity, you may be happier with a fixed power scope. For varmints and plinking .22s, a fixed 4x power scope could work fine. Most handgun scopes are 2x, since a higher magnification with less eye relief would make it more difficult to find your target.


Another thing to consider when buying a riflescope is that your success depends on the quality of your scope, rings, and bases. When it comes to optics, don't cut corners. Get a quality scope and mount, plenty of ammo, and enough time with your scope and gun to make settings, adjustments, and aiming second nature. So when it's time to hunt, you worry about the prey, and not how to use your sight.


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Mounting A Scope
Mounting a scope to a firearm typically takes a scope base to fit the firearm and scope rings to fit the scope. By using the appropriate combination of scope base and rings, a wide range of scopes can be mounted to most firearms.


Rings are circular clamps used to hold the riflescope in place. They are mounted to a base that's been installed on the gun. The inside diameter of the ring must match the outside diameter of the scope – usually 1" or 30mm. The height of the ring should be low enough to be comfortable to the shooter but high enough for the scope to clear the firearm. In choosing the ring height, you must consider the objective lens outside diameter, the ocular bell size, the length of the scope, eye relief, bolt lift, and the barrel contour.


Note that different manufacturers measure ring height differently. Some measure from the base to the ring center, while others measure from the base to the ring's bottom edge. Ring heights are often classified in ranges of low, medium, high, and extra high.


Weaver-style rings are made by many different manufacturers. They clamp onto a 7/8" wide Weaver-style base using a recoil lug that fits the slot on the Weaver base. These lugs prevent the scope from moving during recoil or handling. Most Weaver-style rings are detachable from the base with the scope still in them.


Extension rings have a cantilever that is useful with shorter scopes and allows some manipulation of eye relief.


3/8" dovetail rings fit onto grooved receivers normally found on .22 rifles and airguns. These receivers have grooves running lengthwise in the top of the gun, which provide the claws of the dovetail rings a place to grasp. These rings can also be used with a 3/8" base screwed onto the receiver.


Quick-detach rings use levers to easily remove the scope for transport or cleaning. Quick-detach rings can be Weaver style or another style that may require a matching base. Quick-detach rings do not normally offer a perfect return to zero when reinstalled.


The riflescope base comes in one or two pieces that connect to the firearm receiver using clamps or screws. Scope rings are then mounted onto the base using clamps, screws, or dovetails. Some firearms have bases built into them. The Weaver base might be the most common. It's made by many manufacturers and is available for most guns. Weaver bases are 7/8" wide and designed with recoil slots running crossways.


Picatinny rings and bases are similar to the Weaver style. The main difference is the size of the mounting slots on the top the base and the size of the recoil lugs on the bottom of the rings. The Weaver base has a .180" slot, while the Picatinny base is .206". For this reason a Weaver ring will fit into a Picatinny base, but a Picatinny ring will not fit the Weaver base.


Standard (or Leupold, Redfield, Burris, etc.) style bases are strong and reliable and allow a lot of interchangeability among manufacturers of non-Weaver style systems. Rings on the standard or Leupold system are not easily detached.


Dual dovetail bases are similar to the standard Leupold base except they do not have the windage adjustment screws found on standard bases. However some people prefer the clean lines and fewer parts of the dual dovetail system.


Some riflescope mounts come with the rings and base combined into one piece. Common singe-piece mounts are see-through mounts and saddle mounts.


Keep In Mind
A secure connection is of utmost importance to proper use of your scope. For reliability and confidence in the field, carefully choose your rings and base without cutting corners. If you are unsure about choosing your scope base and rings or mounting your scope, Gander Mountain offers complete firearm service centers with expert gunsmiths that can help. You can check out our Gunsmith Service link here http://www.gandermountain.com/gunsmith/index.shtml.


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Binoculars

Binoculars

Because of their wide variety of uses and ease of operation, binoculars are perhaps the most popular set of optics in the world. Binoculars are basically side-by-side telescopes aligned to point in the same direction allowing both eyes to be used when viewing objects. Unlike a telescope or monocular, binoculars provide the user with a three-dimensional image.


There are a few things to consider when selecting the right binocular for your favorite activities. General use binoculars used for outdoor activities such as hiking or stadium sports should be compact and light with a wide view angle. Consider binoculars that you can put in your pocket or wear on a strap around your neck that also provides a good field of view and about a 7-10x magnification for getting closer to the action. For longer range activities such as long range shooting or varmint hunting, 12-16x magnification would be best. At a large magnification, you might consider using a tripod to steady the binoculars. A slightly shaky hand will be greatly increased at higher magnifications. For boating activities, a higher magnification is not needed. Most marine binoculars are around 7x. Marine binoculars should also be waterproof with rubber armoring and a larger objective diameter of 42 or 50mm.


As with scopes, binoculars are identified by two numbers, the magnification and the objective diameter. For example, viewing through an 8x32 binocular will cause the object to appear 8 times closer than with the naked eye. The second number 32 is the diameter in millimeters of the objective or front lens. The larger the objective lens is, the more light that will enter the binocular and the brighter the image.


Exit pupil is the size of the circle of light visible in the eyepiece. It's determined by dividing the objective diameter by the magnification power. For 8x32 binoculars, 32 divided by 8 equals an exit pupil of 4mm. Relative brightness is determined by squaring the exit pupil size. For our example, the exit pupil of 4mm would have a relative brightness or RE of 16. Twilight factor is another mathematical formula that provides a reference for the amount of detail that can be seen in low light. All of these measurements, exit pupil, relative brightness, and twilight factor are simply rough guides to determining brightness. Lens coatings and optical quality are often more important factors in determining low light detail.


Eye relief is the distance the eyepiece can be held away from the eye and still provide a full field of view. Extended eye relief is especially beneficial to eyeglass wearers. Binoculars also include twist-up or fold-down eyecups which help eyeglass wearers see the entire field of view.


Diopter adjustment enables a fine focus of the individual eyepiece to allow for vision differences in left and right eyes.


Field of view (FOV) is the side-to-side measurement of the viewing area. It's measured by the width of the viewed area in feet at a distance of 1000 yards away. Remember that as magnification increases the field of view will decrease. Most binoculars also have a focus knob. Close focus is the nearest distance at which the binoculars can focus on an object.


Prism Designs
There are two different types of prism systems used in binoculars. The Porro Prism uses a Z-shaped double prism system to reflect the image from the object lens to the eyepiece. This means the objective lens is offset from the eyepiece, and the optical path is greater than the physical length of the binoculars. This wider spacing of the objective lenses provides greater depth perception and a wider field of view.


In the Roof Prism design, the prisms overlap allowing the objective lens to line up with the eyepiece. Roof Prisms allow the binoculars to be more compact and narrower. The Roof Prism does utilize surfaces that may reduce light transmission compared to Porro Prisms resulting in a less bright image.


Most prisms are made from borosilicate (BK-7) glass or barium crown (BAK-4) glass. BAK-4 is a higher quality glass that provides sharper, brighter images.


Lens Coatings
An important factor in determining the quality of the optics in the binocular is the optical coating of the lens. These coatings are used to aid in light transmission. The following terms are used to describe the coatings on the lens surfaces.


Coated Lenses – One or more surfaces with a single layer coating.
Fully Coated – All air-to-glass surfaces with a single layer coating.
Multicoated – One or more surfaces with multi-layer coatings.
Fully Multicoated – All air-to-glass surfaces with multi-layer coatings.


Fully multicoated lenses can provide up to 95% light transmission, which means higher contrast and better resolution.


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Spotting Scopes

Spotting Scopes

A spotting scope or field scope is the best choice for applications requiring higher magnifications and greater distance viewing. Spotting scopes generally offer higher magnifications than binoculars and are designed for single eye observation. Spotting scopes are often used for hunting, birding, surveillance, and viewing distant landscapes or ships. They are also a helpful tool for scoring targets on firearm and archery ranges.


As with binoculars, spotting scopes are identified by the magnification range and the objective diameter. A 15-45x60 spotting scope will have a 15-45x magnification range and a 60mm objective diameter. One thing to consider when deciding on the magnification of a spotting scope is the atmospheric condition where it will be used. Heat waves, humidity, wind, and air currents can reduce image quality, and this is more noticeable at higher magnifications. Generally, higher altitudes and dry climates favor high magnifications. Bear in mind that the quality of the optic system also affects the image quality at high magnification.


A larger objective lens allows more light to enter the scope so you can see more detail. However, a less quality lens, no matter how large, can't match the performance of a smaller, higher quality lens. Objectives that are made out of special quality glass, such as ED glass, HD glass, or APO glass, can deliver images as good as larger objectives made of standard glass.


Other factors to assess include eye relief, the distance the eyepiece can be held away from the eye and still provide a full field of view. Extended eye relief is especially beneficial to eyeglass wearers. Lens coatings improve light transmission, which is important with high magnifications. Premium model spotting scopes are "fully multicoated" to provide the best performance.


As with binoculars, prism designs play a role in image quality seen with spotting scopes. In Porro Prism scopes, the objective lens is offset from the eyepiece which provides a greater optical path with better clarity at magnification. Roof Prism scopes are slim and compact, but they are not as efficient and lack many of the features of the Porro Prism scope.


Also think about the weight of the spotting scope and tripod especially as it relates to the intended use. If you'll be hiking any distance with the scope and tripod, you might find a smaller objective with less weight would be preferred.


Due to its high magnification, a spotting scope requires some support other than your hand to steady it. Spotting scopes have standard threaded holes like cameras for use with any standard tripod. Remember the larger and heavier the scope, the larger and sturdier the tripod needs to be.


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Rangefinders

Rangefinders

The development of laser rangefinders has made it simple to measure the distance to a target. Laser rangefinders use an invisible infrared laser beam that travels from the rangefinder to the target, then reflects back to the rangefinder. A computer inside the rangefinder calculates the time it took for the beam to return and translates that into a distance that is then displayed on a screen. This technology in most rangefinders is accurate to +/- one yard.


Range – Most consumer handheld rangefinders use the same type of laser. However, based on the quality of their construction and the capabilities of their sensor and processor, some rangefinders are able to measure at longer ranges. Keep in mind that there are many variables that occur when determining range, including sun, precipitation, heat waves, the size and color of your target, the texture, and the surrounding terrain. For this reason, it's almost impossible to determine a true maximum range. Some manufacturer's do not list ranges for their models or may make it clear that yardages listed are approximations.


Tilt or Angle Compensation – This feature compensates for any difference in elevation between the user and the target. Rangefinders with angle compensation display the horizontal distance to the target and some even display the angle of tilt between you and the object. This is a great feature to have especially if you do a lot of hunting in the mountains or from a treestand.


Scan Mode – This feature gives you distance readings as you pan back and forth across a landscape. This is helpful in pinpointing your target against a busy background.


Brush Mode – This is a filter that ignores brush between you and your target – a necessity for hunters who deal with objects between them and their target.


Rain or Fog Mode – Fog, rain, and smog can greatly affect the laser beam and thus the readings on a rangefinder. This feature can help to a certain extent, but often heavy fog or weather is just too much for a rangefinder to be useful.


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Red Dot Sights & Laser Sights

Red Dots and Laser Sights


Red Dot Sights
Unlike riflescopes that magnify a target, red dot sights give the shooter an illuminated red dot as an aiming point. Red dot sights are not as useful for precision shooting, but are very helpful in locating targets quickly. Standard models use a red light-emitting diode (LED) to focus an illuminated dot-style reticle that stays in alignment with the firearm.


Dots vary in size from sight to sight. Some sights have dots that are adjustable in size. Others have crosshairs or other choices as well as a dot. The size of the dot is measured in MOA (minutes of angle) which translates to 1" at 100 yds. for each MOA. So a red sight with 4 MOA produces a 4" dot at 100 yds., 2" at 50 yds., or 8" at 200 yds.


Red dot sights generally fall into two categories, "tube" or "open" designs. Tube sights look similar to standard riflescopes with a cylindrical tube containing the optics. Open sights have a flat base with a single loop that support the reflector.


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Laser Sights
Laser sights help in quickly acquiring a target and improving accuracy when making a shot. Improvements in technology have resulted in more powerful lasers that are smaller, lighter, and easier to operate.


Types of Laser Sights
Laser Grip – This laser sight attaches to the grip of a gun and is specifically designed for each style of handgun. Laser grips are designed to be activated by the pressure of your hand, so when you draw the gun from its holster, the laser comes on. Be aware that a laser grip will affect the gun's holster fit as well as your grip on the gun.


Rear Sight Lasers – Lightweight and easy-to-use, rear sight lasers take the place of the rear sight on your handgun. Rear sight lasers tend to be less powerful, but because they are easy to mount and less bulky, they are still a great option.


Trigger Guard Mounted Laser Sights – Because these sights are mounted on the trigger guard, they can be a little larger and more powerful. However, the added size will probably require a new holster, and because of the way they are mounted, they lose their accuracy after even a few shots.


Rail-Mounted Laser Sights – Rail-mounted lasers are generally more powerful with extra features such as adjustments for windage and elevation. When opting for a rail-mounted laser, make sure there is enough space on your rail for the sight.


Laser Colors
Most laser sights use a red laser diode. Red lasers are easier to produce, and the beam strength is strong enough to stand up to recoil. Red lasers also operate better in a wider temperature range. In the late 1990s, green laser diodes became available. The one advantage of a green laser is its daytime visibility. Green lasers are much easier to see in daylight than red lasers. While a red laser may only be visible up to 30 yards during the day, a green laser can be effectively visible for up to 100 yards or more. However, green lasers are much more expensive to produce, and because of the delicate technology used, they are not as durable as red lasers.


Laser Modes
Some laser sights offer a pulsating or strobe mode that is easier for your eye to see. The blinking light draws your eye in, allowing you to find the laser dot quicker, at greater distances, and against different backgrounds. The pulsating mode will also save on battery life.


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Night Vision

Night Vision

Night vision devices use an image intensifier tube to produce images when light is limited or approaching total darkness. From handheld monoculars to helmet-mounted goggle systems, there are several types of night vision devices suited for various applications.


Night Vision Monoculars are versatile devices that can be handheld, head-mounted, or sometimes even weapon-mounted. One of the benefits of the monocular is that one eye remains adjusted to ambient light conditions which is helpful when moving in and out of dark and light.


Night Vision Binoculars are a comfortable viewing system with two eyepieces just like daytime binoculars, but with only one intensifier tube, the range and performance is the same as the monocular.


Night Vision Goggles are devices that are mounted to a headset or helmet. The monocular goggle uses a monocular mounted to a headset. The bi-ocular goggle has two eyepieces but only one front lens, so it offers more viewing comfort but without any vision improvement over the monocular. The binocular goggle has two eyepieces and two front lenses, so it provides depth perception since there are two optical systems.


The purpose of night vision devices is to help you see in the dark and not at great distances. Night vision instruments do not offer the same resolution as daytime devices such as binoculars and riflescopes. When magnification increases, resolution decreases, so because of their limited resolution, magnification is also greatly limited. The best image with night vision is usually received at 1x (no magnification) to about 3x.


Night Vision Generations
The performance of a night vision device mostly depends on which generation it is. Gen 1 Night Vision Devices use the oldest technology and are the least expensive. Gen 1 devices have a pronounced distortion at the edge of the field. Gen 1 devices require an infrared illuminator for use in tough conditions. These units can detect man-sized objects at a range of about 75 to 100 yards under average conditions.


Gen 2 Night Vision Devices offer many advances over Gen 1 Devices. The Gen 2 intensifier tube provides less distortion at the edge of the field, better contrast and resolution, better light amplification, and longer life. Detection range is about 50 to 75 yards further than Gen 1. There is also a greater range of performance within Gen 2 Devices depending on the type of tube and the resolution offered. The better the resolution, measured in line pairs per millimeter (lpm or lp), of the Gen 2 tube, the higher the price.


Gen 3 Night Vision Devices are able to detect human-sized objects at a range of 300 yards or more. Gen 3 tubes have a much longer life and rarely need to be replaced. As with Gen 2 units, resolution and performance will vary among Gen 3 Devices.


Digital Night Vision
The use of digital technology has entered the world of night vision devices creating units that are similar in performance to a Gen 2 device. Digital night vision units are less expensive and easier to use with cameras. They are also sturdy and not susceptible to damage caused by bright light, as most conventional night vision devices are. Digital night vision is available in all types of devices, from monoculars and binoculars to riflescopes.


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Optics Terminology

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Buyer's Guide

Our discussion of Optics 101 has barely scratched the surface of the many technologies that go into producing optical equipment. We hope that in some way it has been helpful in your decision making. If you still have questions or need help in any way, please contact us via phone at 1-888-542-6337, email, or live web chat. We have experts ready to assist you.


If you're able to visit a local Gander Mountain store, you will have the opportunity to see our optical offerings first hand. You can also take advantage of our gunsmiths that are available at each Gander Mountain location. They will be more than happy to assist you with selecting the proper tool. Our gunsmiths also offer professional scope mounting and boresighting services to give you peace of mind in knowing that your gun is ready for the hunt.


So whether you do it yourself or make use of our gunsmith services, Gander Mountain is here to make your complete experience a success.

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