MAGNIFICATION POWER - WHAT DO THE NUMBERS MEAN? (For example 10x42)

The first number is the magnification power, or how many times the image is enlarged. The two most common magnification powers are 8x (8 times larger) and 10x (10 times larger).

Don't be fooled into thinking bigger is better. More power is not always better. Although a higher power binocular will increase the size of the object, higher magnification also magnifies the effects of your hand shaking and it can appear that the image is shaking or perhaps a bit blurry.

Stick to a 7x, 8x or 10x power binocular for best results.

Try typing 10x (for example) in the Search Page: Click Here

The second number indicates the diameter in millimeters of the larger front lens (known as the objective lens). The bigger the objective lens, the more light can enter, and the greater the potential resolution of the image, especially at dusk and dawn. Most popular birder binoculars would be a 42mm.

PORRO PRISM vs. ROOF PRISM

Porro prism binoculars are what you would consider traditional shaped binoculars. They are wide-bodied with a big lens in front and a smaller one in the back. The shape of the binoculars looks a bit like a 'dog leg'.

Roof prisms are longer and sleeker in design with the objective and ocular lenses falling in alignment along the same tube.

Both designs have advantages and disadvantages. Porro prism binoculars have fewer internal elements and are easier to manufacture and repair. Roof prisms, are more expensive but also tend to be more rugged with elements firmly anchored within the barrels.

FIELD OF VIEW (FOV)

The field of view is the size of the area you can see through a binocular. It refers to how much you can see left to right and top to bottom. Field of view is measured in feet at a distance of 1,000 yards from where you would be standing. (An example spec on a binocular would be: Field of View: 356 feet @ 1000 yards.)

Select a field of view that offers a minimum of 300 feet at 1,000 yards.

A wider field of view makes it easier to pick up and identify fast flying birds. This makes it possible to scan a sky, an ocean or an open marsh quickly. Generally, lower magnification binoculars offer a wider field of view than binoculars with higher magnification.

EYE RELIEF

Closely related to field of view, eye relief refers to the distance between the ocular lens and your eye. This is the most important consideration for eye glasses wearers, because glasses hold the eyes back from the eyepieces, and you may not get to experience the same wide fields enjoyed by non-eyeglass wearers.

Normal eye relief for binoculars is measured in millimeters and should be from 9 to 13 mm. Even though the eyecups of most binoculars fold down to let eyeglass wearers get closer, in many cases it's not close enough. If you wear glasses, you need binoculars with a longer eye relief of 14 - 20 mm.

CLOSE FOCUS

The closest distance to the observed object that a binocular can focus down to.

EXIT PUPIL

Hold a binocular up to the light and look in the eyepiece. Exit pupils are the small, bright circles. The exit pupil is the column of light that comes through the binocular to your eye. The larger the exit pupil, the brighter the image.

The exit pupil is calculated by dividing the diameter of the objective lens by the power: (Example 35 divided by 7 = 5). So, a 7x35mm binocular has an Exit Pupil of 5.

SPOTTING SCOPES

Advanced birding involves the careful study of birds over great distances for extended periods of time. For this task, spotting scopes are ideal. Spotting scopes usually rest upon a tripod, making stable, higher magnification possible.

The most popular magnification powers include 20x, 30x, 40x and 60x. Many spotting scopes offer excellent zoom eyepieces and adaption to 35mm cameras as well.

CHECK THE PRICE

Good binoculars simply cost more to manufacture than less expensive ones. Heavier glass, coatings, more precise alignment, better quality control all contribute to a higher cost. Basically, you get what you pay for with binoculars.

WHAT ARE YOU USING THEM FOR?

BIRD WATCHING

A wide range of binoculars may be used for bird watching and nature study. An 8x21 model may be fine for observing a blue jay in your backyard on a bright, sunny day. However, if you are in a shaded area, binoculars with a larger objective lens would allow more light to enhance your view.

Once the basics of binoculars are understood, the decision will be easier. A good pair of binoculars will give you a good field of vision, be able to focus quickly, fit your hands, are still okay when knocked to the ground, be able to withstand some rain or fog, and allow you to see objects both near and far.

Generally, an 8 or 10 times magnification combined with an objective of between 30mm to 42mm is the best combination.

BOATING / YACHTING

Most manufacturers feature a 7x50 model as their marine binocular. The large 50mm objective lenses perform well in low light conditions. If you plan to view at great distances, a 10x50 model might be better. For those viewing only in bright daylight conditions who prefer a more compact model, an 8x21 or 8x25 would work well. Also note, Rubicon (Ruby red) coated objective lenses are helpful in reducing glare in bright sunlight, and/or over the water.

CAMPING / HIKING

The outdoor enthusiast will probably be carrying much of their gear and would therefore want to keep the load as light as possible. See our compact / Travel section for best choices. 

ASTRONOMY

With binoculars the Moon is fascinating through all the lunar phases and even Jupiter and the four moons that Galileo saw is quite possible.

Any binoculars will show you a lot more than you can see without them and wherever possible try to steady them with either a standard tripod or just lean against a fence or post.

For those keen to explore the night sky we recommend that you check our telescopes section.

Of particular interest for use in astronomy is the ratio between magnifying power and objective lens diameter. Due to the way binoculars are made, the resulting ratio is the diameter of the final exit pupil on the oculars. For example, a 10x50 binocular produces a 5 mm exit pupil (objective size divided by the magnifying power).

For maximum efficiency, this image should match the diameter of the eye's pupil, which in dark environments grows to about 7mm.

This ratio is also a measure of the brightness of the image, the larger the exit pupil, the brighter the image reaching the eye. Therefore, 10x50 and 8x40 binoculars have the same brightness, although the latter has a smaller magnification.

An exit pupil larger than the diameter of the user's eye pupil wastes light.

Binoculars are widely used by amateur astronomers. Their wide field of view is central to their use in comet hunting and general sky observing. 

SPECTATOR SPORTS

Race enthusiasts know that good binoculars are an important piece of gear for catching a closer glimpse of the action. A wide angle binocular which offers the advantage of a wider field of view will let you see more of the track and, consequently, more of the action. Focus free binoculars allow you to simply pick up the binoculars and view, without having to make time-consuming focusing adjustments. 

A night game is better seen with larger objectives, a day-time event can be viewed with a more compact binocular. If you are in a large stadium watching a football game, (depending on where your seats are), a pair of 7x35 binoculars might be ideal. If you are seated at one end, or in the upper rows of the stadium, 10x50 would be better suited for your needs.

SURVEILLANCE

These binoculars offer many performance options: lightweight, wide angle and zoom among them. Zoom binoculars can capture a panorama of action at low power, then zoom in to pick up all the details at higher powers.

TRAVEL / SIGHTSEEING

The needs of travellers are diverse. As such, the features and benefits of the various binoculars are equally diverse. The recommended binoculars for travel and sightseeing range from compact, lightweight models that go everywhere, to large zoom models that allow for a range of magnifications in one binocular. Whatever your pleasure, we have a binocular to fit your need.

BINOCULAR STYLES

Compact: binoculars offer the advantage of being extremely portable and lightweight. With the prisms positioned one over the other utilising the Roof prism design, the objective lenses and the eyepiece centers are lined up creating a compact design with full size power. Some compact binoculars will even fit into jeans and jacket pockets.

Full size: binoculars offer superior light gathering capabilities and wide fields of view.

Zoom: binoculars allow you to lock onto a subject, then zoom in for a closer view. Zoom binoculars have two power numbers which represent a range of powers. A 10-30x50 binocular for example, brings objects from 10 to 30 times closer.

Focus-Free: binoculars offer a "no focus" mechanism which means the binoculars are always in focus.  Simply pick them up and look. They're always in focus ready to catch all the action and are proving to be very popular with people who need to look quickly to catch something such as plane-spotters, travellers and yachtsmen.

Please note however that they are designed for people with normal or corrected to normal vision. The distance from which they are in focus varies from person to person.

Wide angle: binoculars offer greater field of view without sacrificing power. By altering the design and shape of the binocular's lenses an increased field of view can be obtained without sacrificing power.

Wide angle binoculars are ideal for sports events to capture quick movements, or for races when the action is spread over a broad area or for travel where a panoramic view is desired.

Rubber armoured: binoculars provides multiple benefits. It helps protect the binocular from the bumps and scratches by absorbing shocks that occur with general use. It provides a comfortable, ergonomic, non-slip gripping surface for making them easier to hold on to, particularly in the elements, while insulating your hands against extreme temperature. It's easy to wipe clean after a tough day in the field. And it suppresses noise if the binocular bumps aluminum or other non-rubber surfaces, which might otherwise spook wildlife

Waterproof: binoculars have been hermetically sealed and nitrogen charged to remain dry when submersed in water. They have been tested underwater and proven to be completely waterproof.

Some binoculars are O-ring sealed and nitrogen-purged for total waterproof and fog proof protection. These models can withstand complete immersion in water and stay dry inside. The interior optical surfaces won't fog due to rapid temperature change or humidity.

To accommodate boaters and fishermen, models also include a built-in compass and a range-finding reticle.

To complement our waterproof binoculars we suggest our floating binocular straps, which offer extra comfort as well as extra security in case of accidental spills overboard.

Tripod Adapter and Bracket

When a binocular reaches higher powers (generally over 12x) you will need some assistance to hold it steady enough for comfortable viewing. While leaning against a fence or tree will often suffice, a much better solution is to use a tripod. Most higher magnification models will include a tripod adapter fitting at the base of the hinge (covered by a screw-in cap).

A monocular is a modified refracting telescope used to magnify the images of distant objects by passing light through a series of lenses and prisms ; the use of prisms results in a lightweight telescope. Volume and weight are less than half those of binoculars, making it easy to carry along.

It's not possible to label individual binoculars as the best for any particular use or situation due to variables such as usage conditions, individual preference, how and where the instrument will be used, and the range of different viewing situations the instrument will be used for. Only you can determine what will be the best, most versatile and satisfactory optical instrument for you, and you shouldn't be discouraged from any choice you make, because you know your own needs and interests. We encourage you to look through the information provided at this site on the different models, then ask us for a demonstration. Whichever product you choose, rest assured that you'll receive excellent value for your investment.

The brilliance and sharpness of the image you see through a particular binocular or spotting scope is determined by a number of different factors. Magnification, optical coatings, and lens diameter are just a few of the factors influencing how a binocular performs.

However, the single most important criterion in performance will always be the quality of the optics. Optical excellence is delivered through careful consideration of quality in the glass and lens coatings used, precision manufacturing processes, and uncompromising quality control.

SPOTTING SCOPES

A spotting scope is a portable telescope , optimised for the observation of terrestrial objects. The magnification of a spotting scope is typically in the order of 20x to 60x. Other common features include:

• somewhat "rugged" or rubber-armoured design
• convenient mounting for attaching to a tripod
• ergonomically designed and located knob for focus control
• tethered elastomeric lens cap
• a range of eyepieces to give different magnifications, or a variable "zoom" eyepiece to give a range of magnifications (e.g. 20-60x)

The light gathering power of a spotting scope is determined by the width of the objective lens , typically between 55 and 80mm. All else being equal, the larger the objective, the more heavy and expensive the telescope.

There are three types of scope: "straight-through" (the eyepiece is one the same axis as the body of the scope), "angled" (the eyepiece is at an angle of about 45 degrees to the body of the scope), and rarely, a more complex, shoulder-mounted design. Straight-through scopes are easier to use from, say, inside a car, while angled scopes are more comfortable for tall people and more easily shared by people of different heights.

The choice of the eyepiece lens determines the overall magnification. The best magnification is decided by a number of factors. Magnifications of less than 20x are unusual, as (much cheaper and lighter) binoculars or monoculars can provide this. Magnifications of more than 60x lead to poorer brightness and, even on a tripod, shake can be a problem. The field of view is also limited.

Usually for birding , 20x or 30x is favoured. This gives a good field of view and a bright image.

NIGHT VISION TERMINOLOGY

From here until the end, we are referring specifically to Night Vision products

Automatic Brightness Control (ABC)
An electronic feature that automatically reduces voltages to the microchannel plate to keep the image intensifier's brightness within optimal limits and protect the tube. The effect of this can be seen when rapidly changing from low-light to high-light conditions; the image gets brighter and then, after a momentary delay, suddenly dims to a constant level.

Auto-Gated Power Supply
When the power supply is "auto-gated," it means the system is turning itself on and off at a very rapid rate. This, combined with a thin film attached to the microchannel plate (an ion barrier) reduces blooming. While "blooming" can be noticeably less on systems with a thin film layer, systems with thicker film layers can be perfectly acceptable depending on the end user's application. Deciding which night vision goggle is better should not be based solely on blooming.

Black Spots
These are common blemishes in the image intensifier of the NVD or can be dirt or debris between the lenses of the NVG. Black spots that are in the image intensifier do not affect the performance or reliability of a night vision device and are inherent in the manufacturing processes. Every night vision image intensifier tube is different. They are like diamonds. See image to the right. See also - How to Buy Night Vision Equipment

Bright Spots
These can be defects in the image area produced by the NVG. This condition is caused by a flaw in the film on the microchannel plate. A bright spot is a small, non-uniform, bright area that may flicker or appear constant. Bright spots usually go away when the light is blocked out and are cosmetic blemishes that are signal induced.

Biocular
Viewing a single image source with both eyes (example: watching a television set).

Binocular
Viewing a scene through two channels; i.e. one channel per eye.

Blooming
Loss of the entire night vision image, parts of it, or small parts of it, due to intensifer tube overloading by a bright light source. Also, known as a "halo" effect, when the viewer sees a "halo" effect around visible light sources. When such a bright light source comes into the night vision device's view, the entire night vision scene, or parts of it, become much brighter, "whiting out" objects within the field of view. Blooming is common in Generation 0 and 1 devices. The lights in the image to the right would be considered to be "blooming".

Bright-Source Protection (BSP) - High-Light Cut-Off
An electronic function that reduces the voltage to the photocathode when the night vision device is exposed to bright light sources such as room lights or car lights. BSP protects the image tube from damage and enhances its life; however, it also has the effect of lowering resolution when functioning.

C-Mount
A standard still and video camera lens thread size for mounting to the body of a camera. Usually 1/2" or 3/4" in diameter.

COMSPEC (Commercial Specification)
A term used to describe image tube quality, testing and inspection done by the original equipment manufacturer (OEM).

Chicken Wire
An irregular pattern of dark thin lines in the field of view either throughout the image area or in parts of the image area. Under the worst-case condition, these lines wwill form hexagonal or square wave-shape lines.

Daylight Lens Cover
Usually made of soft plastic or rubber with a pinhole that allows a small amount of light to enter the objective lens of a night vision device. This should be used for training purposes only, and is not recommended for an extended period of time.

Daylight Training Filter
A glass filter assembly designed to fit over the objective lens of a night vision device. The filter reduces light input to a safe (night-time) level, allowing safe extended daytime use of the night vision device.

Diopter
The unit of measure used to define eye correction or the refractive power of a lens. Usually, adjustments to an optical eyepiece accomodate for differences in individual eyesight. Most ITT systems provide a +2 to -6 diopter range.

Distortion
There are two types of distortion found in night vision systems. One type is caused by the design of the optics, or image intensifier tube, and is classical optical distortion. The other type is associated with manufacturing flaws in the fiber optics used in the image intensifier tube.

Classical Optical Distortion:

Occurs when the design of the optics or image intensifier tube causes straight lines at the edge of the field of view to curve inward or outward. This curving of straight lines at the edge will cause a square grid pattern to start to look like a pincushion or barrel. This distortion is the same for all systems with the same model number. Good optical design normally makes this distortion so low that the typical user will not see the curving of the lines.

Fiber Optics Manufacturing Distortions: Two types of fiber optics distortions are most significant to night vision devices: S-distortion and shear distortion:

S-Distortion: Results from the twisting operation in manufacturing fiber-optic inverters. Usually S-distortion is very small and is difficult to detect with the unaided eye.

Shear Distortion: Can occur in any image tube that use fiber-optic bundles for the phospor screen. It appears as a cleavage or dislocation in a straight line viewed in the image area, as though the line were "sheared".

Equivalent Background Illumination (EBI)
This is the amount of light you see through a night vision device when an image tube is turned on but no light is on the photocathode. EBI is affected by temperature; the warmer the night vision device, the brighter the background illumination. EBI is measured in lumens per square centimeter (lm/cm2). The lower the value the better. The EBI level determines the lowest light level at which an image can be detected. Below this light level, objects will be masked by the EBI.

Edge Glow

There is a defect in the image area of the NVG. Edge glowis a bright area ( sometimes sparkling) in the outer portion of the viewing area.

Emission Point
A steady or fluctuating pinpoint of bright light in the image area that does not go away when all light is blocked from the objective lens. The position of an emission point within the field of view will not move. If an emission point disappears or is only faintly visible when viewing under brighter nighttime conditions, it is not indicative of a problem. If the emission point remains bright under all lighting conditions, the system needs to be repaired. Do not confuse an emission point with a point of light source in the scene being viewed.

Eye Relief
The distance a person's eyes must be from the last element of an eyepiece in order to achieve the optimal image area.

Field-of-View
The diameter of the imaged area when viewed through an optic

Figure of Merit (FOM)
Image Intensification tube specification designation, calculated on line pair per mm x signal to noise.

Fixed-Pattern Noise (FPN)
A faint hexagonal (honeycomb) pattern throughout the image area that most often occurs under high-light conditions. This pattern is inherent in the structure of the microchannel plate and can be seen in virtually all Gen 2 and Gen 3 systems if the light level is high enough.

Footlambert(fL)
A unit of brightness equal to one footcandle at a distance of one foot.

Gain
Also called brightness gain or luminance gain. This is the number of times a night vision device amplifies light input. It is usually measured as tube gain and system gain. Tube gain is measured as the light output (in fL) divided by the light input (in fc). This figure is usually expressed in values of tens of thousands. If tube gain is pushed too high, the tube will be "noiser" and the signal-to-noise ration many go down. In any night vision system, the tube gain is reduced by the system's lenses and is affected by the quality of the optics or any filters. Therefore, system gain is a more important measurement to the user.

Generations
Two technologies are referenced as night vision; image intensification and thermal imaging (see definitions). Because of cost and the fact that image intensifier scenes are easier to interpret than thermal (thermal images show targets as black or white - depending upon temperature - making it more difficult to recognize objects), the most widely used night vision aid in law enforcement is image intensification equipment.

Generation 0
The first night vision aids (also called Generation Zero or Gen 0) were sniper scopes that came into use during World War II and the Korean conflict. These were not true image intensifiers, but rather image converters, which required a source of invisible infrared (IR) light mounted on or near the device to illuminate the target area.

Generation 1
The "starlight scopes" developed during the early 1960's for use in Vietnam were the first Generation (Gen 1) of image intensifier devices. In Gen 1 night vision units, three image intensifiers were connected in a series, making the units longer and heavier than future night vision units would be. Gen 1 equipment produced an image that was clear in the center of the field of view but suffered from large optical distortion around the periphery. Gen 1 equipment was also subject to "blooming". Most low-cost imported night vision units use Gen 1 technology, though often under the guise of a higher "generation".

Generation 2
The development of the microchannel plate, or MCP, in the late 1960s brought on the second generation (Gen 2) in night vision. The MCP accelerated and multiplied electrons which provided the gain previously supplied by coupling three image intensifiers together (Gen 1). The introduction of the MCP significantly reduced size and weight for image intensifier tubes, enabling design of smaller night vision goggles and hand-held devices. The MCP also provided much more robust operation when bright lights entered the field of view. The Gen 2 tubes used the same tri-alkali photocathode as the Gen 1 devices. This generation was implemented to reflect the change in how the light was amplified (MCP versus three-stage coupling).
 
Highlight Shutoff
An image intensifier protection feature incorporating a sensor, microprocessor and circuit breaker. This feature will turn the system off during periods of extreme bright light conditions.

Interpupillary Adjustment
The distance between the user's eyes (pupils) and the adjustment of binocular optics to adjust for differences in individuals. Improperly adjusted binoculars will display a scene that appears egg-shaped. 

IR Illuminator
Many night vision devices incorporate a built-in infrared (IR) diode that emits invisible light or the illuminator can be mounted on to it as a separate component. IR light cannot be seen by the unaided eye; therefore, a night vision device is necessary to see this light. IR Illuminators provide supplemental infrared illumination of an appropriate wavelength, typically in a range of wavelengths (e.g. 730nm, 830nm, 920nm), and eliminate the variability of available ambient light, but also allow the observer to illuminate only specific areas of interest while eliminating shadows and enhancing image contrast.

IR Laser
High-power devices providing long-range illumination capability. Ranges of several thousand meters are common. Most are not eye-safe and are restricted in use. Each IR laser should be marked with a warning label like the one shown here: Consult FDA CFR Title 21 for specific details and restrictions.

Lumen: Denotes the photons perceptible by the human eye in one second.

Monocular
A singlechannel optical device.

Photocathode:
The input surface of an image intensifier tube that absorbs light energy (photons) and in turn releases electrical energy (electrons) in the form of an image. The type of material used is a distinguishing characteristic of the different generations.

Resolution
The ability of an image intensifier or night vision system to distinguish between objects close together. Image intensifier resolution is measured in line pairs per millimetre (lp/mm) while system resolution is measured in cycles per miliradian. For any particular night vision system, the image intensifier resolution will remain constant while the system resolution can be affected by altering the objective or eyepiece optics by adding magnification or relay lenses. Often the resolution in the same night vision device is very different when measured at the centre of the image and at the periphery of the image. This is especially important for devices selected for photograph or video where the entire image resolution is important. Measured in line pairs per millimetre (lp/mm).

Reticle (Reticle Pattern)
An adjustable aiming point or pattern (i.e. crosshair) located within an optical weapon sight

Signal-to-Noise Ratio (SNR)
A measure of the light signal reaching the eye divided by the perceived noise as seen by the eye. A tube's SNR determines the low-light-resolution of the image tube; therefore, the higher the SNR, the better the ability of the tube to resolve objects with good contrast under low-light conditions. Because SNR is directly related to the photocathode's sensitivity and also accounts for phosphor efficiency and MCP operating voltage, it is the best single indicator of an image intensifier's performance

Scintillation
Also known as electronic noise. A faint, random, sparkling effect throughout the image area. Scintillation is a normal characteristic of microchannel plate image intensifiers and is more pronounced under low-light-level conditions

Screen
The image tube output that produces the viewable image. Phosphor (P) is used on the inside surface of the screen to produce the glow, thus producing the picture. Different phosphors are used in image intensifier tubes, depending on manufacturer and tube generation. P-20 phosphor is used in the systems offered in this catalogue

Stereoscopic Night Vision
When two views or photographs are taken through one device. One view/photograph represents the left eye, and the other the right eye. When the two photographs are viewed in a stereoscopic apparatus, they combine to create a single image with depth and relief. Sometimes this gives two perspectives. However, it is ususally not an issue because the object of focus is far enough away for the perspectives to blend into one.

System Gain
Equal to tube gain minus losses induced by system components such as lenses, beam splitters and filters.

Variable Gain Control
Allows the user to manually adjust the gain control ( basically like a dim control ) in varying light conditions. This feature sets the PVS-14 apart from other popular monoculars that do not offer this feature.

Zeroing
A method of boresighting an aiming device to a weapon and adjusting to compensate for projectile characteristics at known distances.