advanced professional binoculars reviews,knowledge

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knowledge - binoculars


1.What is a binocular?

2.Classification of Optical Systems

3.The Optical "Tripod"

4.Binoculars Features

5.Types of Binoculars

6.Choosing the Right Binoculars

7.How To Choose Use Recommendations

8. What Will The Binoculars Be Used For?

9. Which binocuolar to choose?

*** What is a binocular?

Small optical instrument consisting of two similar telescopes mounted on a single frame so that separate images enter each of the viewer's eyes. As with a single telescope (monocular), distant objects appear magnified, but the binocular has the additional advantage that it substantially increases the range of depth perception of the viewer because the magnified images are seen with both eyes. The frame of a binocular is usually hinged to permit adjustment of the distance between the telescopes. Focusing can be done by means of a wheel on the central axis between the telescopes; turning the wheel changes the distance from the objective lenses of the telescopes to the eyepieces. Separate focusing of each telescope from the eyepiece may be provided in some types of binocular. The term binocular now usually refers to the prism binocular, in which light entering each telescope through its objective lens is bent first one way and then the other by a pair of prisms before passing through one or more additional lenses in the eyepiece. The prisms aid in reducing the length of the instrument and in enhancing the viewer's depth perception by increasing the distance between the objective lenses. Other types of binocular include the opera glass and the field glass; both use Galilean telescopes, which do not employ prisms and which usually have less magnifying power than the telescopes in prism binoculars. A binocular is often specified by an expression such as 740 or 1242 the first number indicates how many times the binocular magnifies an object and the second number is the diameter of either objective lens in millimeters. The size of an objective lens is a measure of how much light it can gather for effective viewing.
Binoculars magnify distant objects so that they appear nearer and larger to the viewer. A binoculars essentially consist of a pair of parallel telescopes joined at the center by a hinge. The hinge allows the eyepieces to be brought to a suitable interpupil distance for each individual.
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*** Classification of Optical Systems


Prism Design
Binoculars have left and right side barrels linked to each other by an axle. Light enters the objective lenses and travels via prisms to the eyepieces. These two most commonly types of prism systems have resulted in two basic design types.
1) Porro prism design ( named after Ignatio Porro,the Italian physicist who invented them in 1823 and first used them in binoculars), i.e. the classic design
Porro Prism binoculars are characterized by the eyepieces being offset from the objective lenses.
A distinctive shape characterised internally by the use of a combination of two right angle porro prisms and externally by the offset positioning of the eyepieces from the objective lenses.
In optics jargon, this is called a compound lens which reduces distortion. The light then passes through the Porro prism (or roof prism in a more compact design). The prism serves two purposes: it produces erect images and folds the light path to reduce the physical size of the binoculars. Light then passes through eyepieces and enters your eye. One of the two eyepieces is usually adjustable to adaptor to each user. Both eyepieces are adjusted together by center focusing.
2) Roof prism design, i.e. the modern disign
Roof Prism binoculars feature lenses positioned in line for a more compact design.
With the prisms positioned one over the other, the objective lenses and the eyepieces are in line. The result is a more compact design which allows compact binoculars to have full size power capabilities.
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*** The Optical "Tripod"

Like a three legged stand (tripod), binocular performance balances on three legs - 1), 2), 3) as follows :.
1) Magnification (or Power, how close it makes things appear) and Aperture (or Diameter of Objective Lenses)
As you will see these numbers imprinted on the binocular itself, Binoculars are specified mainly by a combination of two numbers e.g. 7x40, 7x50 or even 12x42. For example, 7x45 binoculars provide 7-times magnification and have 40mm aperture of objective lenses.
The first number is the size of the binoculars magnification or power itself, which is the degree to which the object being viewed is enlarged. With a 7x40 binocular the image is 7 times larger than what you see with the naked eye. The level of power affects the Brightness of an image, so the lower the power of a binocular, the brighter the image it delivers will be. In general, increasing power will reduce both field of view and eye relief, which are also discussed here.
For any practical application, magnification usually ranges from 4 to 12. Anything higher than a power of 12x is not desirable for several reasons :
(i) the amount of light reaches the eyes decreases with increasing power so that the object appears darker at higher magnification, powerful binoculars are useless if the image is dim or fuzzy.
(ii) the field of view decreases with increasing power; and, most importantly,
(iii) the higher the power, the more sensitive viewing is to any little movement. As a matter of fact, viewing through a pair of 15x binoculars is an exhausting experience because even your heart beat or breathing with make the image dance around!

The second number refers to aperture or the diameter of objective lens (the lens furthest from the eye and closest to the object you are looking at) in millimetres. A larger objective lens will take in more light to enhance Resolution and Brightness although there are limits to the amount of light that your eye can receive. It determines the light gathering ability of the instrument, with the greater light gathering ability of a larger lens translating into greater detail and image clarity. This is especially useful in low light conditions and at night.
Doubling the size of the objective lenses quadruples the light gathering ability of the binocular. For instance, a 7x50 binocular has almost twice the light gathering ability of a 7x40 binocular and four times the light gathering ability of a 7x25 binocular. This might lead you to assume that bigger is better when it comes to the diameter size of the objective lenses, but in reality the size of the lens must be considered along with Exit Pupil and intended usage to determine the best binocular for you.

2) Resolution (sharpness and clarity)
Resolution is a measurement of the binoculars ability to distinguish fine detail (sharpness and clarity), also referred to definition, is the ability of a binocular to distinguish fine detailand retain clarity Better resolution also provides more intense colour. All else being equal (and it rarely is) a larger Aperture will always deliver more detail to the eye than a smaller Aperture lens regardless of the magnification.
In fact, actual resolution hinges on variety of factors: the quality of the optical components, light transmission through the binoculars, existing atmospheric conditions (e.g. heat haze), optical and mechanical alignment (called collimation - please don't drop binoculars) and the visual acuity of the user (your eyesight).

3) Brightness (light transmission)
Aperture determines the amount of light that the binocular takes in to send to your eye. This in turn largely determines the brightness of the image that you see. The larger Aperture of the objective lens, the greater the brightness and the Resolution (sharpness and clarity, resolving power) of the binocular and of the image seen through the binocular.
It follows then, that a binocular with a large Aperture of objective lens is best for light conditions such as late afternoons, overcast days and astronomy (star gazing). Though a larger aperture of objective lens means more light enters your eyes, it also means a larger and longer binocular body. If you want to carry around a pair of binoculars, a suitable aperture objective lens is between 20 and 50 mm.
Brightness can also be improved through the use of optical coating or use a variety and combination of coatings to produce binoculars suited for all situations. All lenses are usually optically coated to reduce scattered light and improve light transmission. One of the most popular coatings on the objective lens is ruby coating, which provides both performance and durability. Optical glass (selected lens and prism) surfaces are coated by magnesium fluoride to reduce light loss and glare due to reflection. Most binoculars are fully multi-coated to further enhance viewing and reduce eye strain. Some binoculars have a special image enhancing, amber, high contrast coatings.
Main methods of Coating :
Fully Coated: all air to glass surfaces are coated.
Multi-Coated: One or more surfaces of one or more lenses have been coated with multiple films.
Fully Multi-Coated: all air-to-glass surfaces have been multi-coated.
Rubicon tm (Ruby) Coated: Unique to TASCO our Rubicon coating consists of 14 layers of varying colours and composition on the objective lenses. Because of their ability to filter out uncomfortable red light and provide brilliant daylight viewing, this is especially suited to binoculars being used to view objects over water, snow or other bright conditions.
UVC (ultraviolet) Coated: Removes the glare resulting from excess ultra-violet rays in the atmosphere providing a clearer more vivid image especially in brilliant sunlight.

Please consider the following other factors when choosing a kind of binoculars.
1) Field of View (FOV)
The Field of View (FOV) is the width of the area that you can see through the binoculars, which is usually given as degrees or as length at 1000 yards. The FOV is usually printed on the binocular - sometimes as 'x feet at 1000 yards' or sometimes as 'y degrees'. In the latter case 1 degree approximately equals 52 feet at 1000 yards.
As a general rule the field of view will decrease as Magnification increases. However FOV is dependent on many factors and higher quality binoculars will have a larger FOV than their cheaper counterparts.
Usually ranges from about 2 to 10 deg, the FOV can also be increased by changing the design and shape of the binoculars lenses and these are known as Wide-Angle Binoculars.
The size of the area that can be seen while looking through a pair of binoculars is referred to as the field of view. The angular field of view is indicated on the outside of the binocular, in degrees. The linear field of view refers to the area that can be observed at 1,000 yards, and is expressed in feet. A larger field of view translates to a larger area seen through the binocular.You can use angular field to calculate the linear field by multiplying the angular field by 52.5. For example, if the angular field of a particular binocular is 8, then the linear field will be 420 feet, i.e. the product of 8 x 52.5.
in general. A large field of view is especially desirable in situations where the object viewed is likely to move, or when the user is moving.
2) Exit Pupil
The exit pupil refers to the size of the shaft of light transmitted to the eye. The more light, the better the contrast. You can actually see the exit pupil by holding the eyepiece of the binocular approximately 12 inches from your eye. It is the bright circle of light in the center of the eyepiece. Exit pupil is expressed in millimeters and is normally derived by dividing the power into the objective lens diameter. A 7x50 binocular has an exit pupil of 5mm (50 7).
3) Focusing Range
All binoculars have the ability to be focused for infinity. So a primary point of distinction between binocular models is the minimum focus range. Birders tend to favor models with a short focus range of about 15 feet, but 20 to 25 feet is usually acceptable.
4) Stray Light
When light entering the binoculars reflects off of interior surfaces, the reflected light eventually exits inside the binoculars in the form of stray light. This unfocused light typically diminishes the image quality of the sight picture.
5) Twilight Performance
Using the below formulas gives a basic evaluation of low light performance, however, one must keep in mind that they are mathematical formulas and do not take into effect some of the most critical features in optics; glass quality, number of lenses, precision of manufacturing and coating.

In a word, the Resolution and Brightness of the image you see through a particular binocular or spotting scope is determined by a number of different factors, including the interaction of these factors. Magnification, optical coating and Aperture 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. We deliver optical excellence through careful consideration of quality in the glass and lens coatings used, precise manufacturing processes, and excellent Quality Control(Q.C.).
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*** Binoculars Features

1) Wide-Angle Binoculars (i.e. our 7x50)
By altering the design and shape of the binoculars lenses an increased Field of View can be obtained without sacrificing power. Wide angle binoculars are ideal for sports events such as Football 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.
2) Zoom Binoculars
Zoom binoculars have two power numbers which represent a range of powers. There are two kinds of Zoom Binoculars :
One is continuous and uninterrupted, the other is discontinuous and interrupted. A 8-20x50 binocular for example, brings objects from 8 to 20 times closer! For continuous and uninterrupted Zoom,it's like having 13 binoculars in one! But for discontinuous and interrupted Zoom, it's perhaps 8, 10, 12, 15, 20, or other.
3) InFocus tm - Focus Free Binoculars
InFocus binoculars are designed without a focus mechanism. Simply pick them up and look. They aree 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 (who only catch glimpses of things between swells).
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.
4) Compact Binoculars
With the prisms positioned one over the other utilising the Roof prism design, the objective lenses and the eyepiece centres are lined up creating a compact design with full size power. Some compact binoculars will even fit into jeans pockets or a cigarette packet!
5) Long Eye Relief Binoculars for Spectacle Wearers
If you wear spectacles or sunglasses and look through a binocular, you may have noticed that its like looking down a long tunnel. The long eye relief binoculars such as the Future range, are especially designed to solve this problem.
The optics within the long eye relief system direct the focal point further back behind the eyepiece so that you can see the full field of view whilst wearing your glasses (spectacles or sunglasses).
Though all standard binoculars have eyecups that fold away to accommodate eyeglass wearers, the long eye relief binoculars provide the advantage of complete ease of use for spectacle and eyeglass wearers (and for those who don't as well in the meantime).
6) Waterproof and Fogproof Binoculars
This describes a binocular's ability to remain completely dry on the inside when exposed to moisture or total submersion in water. Binoculars are sealed with O-rings and are filled with 100% arid nitrogen, which also resists all forms of moisture.They have been tested underwater and proven to be completely waterproof.
Hermetically sealed and nitrogen charged, these binoculars are fogproof in extreme temperatures and conditions as well as being completely waterproof.
7) Rubber Armoured
The rubber armour covering on many of binoculars absorbs shocks, provides a non-slip surface, offers some weather protection and insulates your hands against extremes of temperature.
8) Tripod Adapter and Bracket
When a binocular reaches higher powers (generally over 15x) you will need some assistance to hold it steady enough for comfortable viewing. While leaning against a fence or tree etc will often suffice, a much better solution is to use a tripod. Most of these models will include a tripod adapter fitting at the base of the hinge (covered by a screw-in cap).

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*** Types of Binoculars

1) The Standard
Excellent all-around binocular for birding, shooting, hunting and outdoors. Ideal for a wide range of viewing. Comfortable size and weight. Great binoculars for a closer look at those unexpected sights. Optimum balance of magnification, brightness and field of view.
2) Compact Binoculars
Small Size, High Power Small enough to slip into pocket or purse; strong enough to carry you into the center of the action. Rugged outdoor models.
3) Marine Binoculars
Waterproof, Fogproof Protection binoculars deliver clarity despite foul weather conditions including fog, rain, ice, and salt water. Standard equipment for serious sailors, avid hunters, hiker and other all-weather outdoors.
4) Zoom Binocular
Distant View, Near View Get the best of both worlds. Locate the action at a distance, then zoom in for closer inspection at the touch of a lever. Variable magnification lets you glide from the far turn to the homestretch. Great for tracking fast moving action across wide areas such as football, soccer, or racetracks.
5) Astronomical Binoculars
Power and Brightness Approach the power of a telescope with the comfort only delivered by a binocular. These binoculars are excellent for astronomy, surveillance, and nature study where close-up detail and long distance viewing are needed even under poor light conditions.
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*** Choosing the Right Binoculars

Selecting the right binoculars is a matter of picking the best combination of features for your specific needs. You should consider magnification, bulk and weight, brightness, field of view, optical quality, and cost.
For any given magnification, larger objective lenses gather more light and yield a brighter image in dim light, but result in a bulkier, heavier binocular.
The higher the power, the "shaker" the image will be, because small hand movements are exaggerated. Therefore, we recommend a binocular of moderate magnification (7x) unless more power is specifically required.
Lower power binoculars usually offer a wider field of view, allowing you to take in more of a scene at one time.
Binoculars also always come in handy, whether you're an avid hunter or an occasional audience or spectator in theatre or stadium. They are essential gear for camping and hiking, a day in the field or a vacation trip to the most adventurous location. Choosing the best binocular for your needs isn't always easy. Consider when, where and how often you plan to use them in order to select a binocular with a combination of features that are right for you. We have given you some pointers that we feel will help you make your decision, and enjoy your purchase to its fullest.
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*** How To Choose Use Recommendations

1) Stadium Sports
4X21, 8X25, & 10X25 Xtra-Wide Angle, and Zoom Features are an added plus. The wide angle will keep you zoomed in on the action
2) Boating Any Waterproof model with a large objective lens and rubberized armor
1X50, 7X42, 8X42 or 10X42
3) Conctert &Theatre
5X25 8X25 Wide Angle. 4X30, 7V18, 10X42; compacts. Any Zoom or Wide Angle Model.
4) Outdoor/Nature
Any 7X35, 7X50, 8X42, standards, 8X30 & 10X30 compacts. Waterproof models are great-just in case.
5) General Use/ Vacation
7X35, 8X42, 10X42 Standards, 8X30 & 10X30 Compacts, Compact and Wide angle model are best.
6) Hunting Rubber armored, waterproof, and fogproof modesl
are best at 7X or 10X. 12X or 16X for distant game/varmints. Compacts in a pocket for a hunter on the move.
7) Bird Watching
8X42 is standard, 10X42, 10X50 & 12X50 for details in smaller species. At a distance, compact with a 30mm or greater objective, any binocular with a long eye relief and good close focusing ability.
For more professional birdwatching, you may choose spotting scopes.
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*** What Will The Binoculars Be Used For?

1) Astronomy
For stargazing, light gathering is the most important factor. Choose a pair of binoculars with at least a 50mm aperture. our 7x50 model is easily hand-holdable and provides nice, wide-field views of starry swaths. The higher power 12x42 is also popular, and in fact is preferable to the 7x50 where skyglow is a problem. "Giant" binoculars of 70mm, 80mm or 100mm aperture will reveal fainter deep-sky objects and more subtle detail, but a tripod is recommended for a steady view. If you can afford the higher price (and a good tripod) and don't mind the extra bulk, you'll be rewarded with incredible views. (The item of giant binoculars, spotting scopes and telescopes are collecting, coming soon.)
The human eye on average has a 7mm pupil at night, so can be said that we look at the world through a pair of 1x7 binoculars! It follows then that even a small pair of 7x40 binoculars will show you a lot more detail than your unaided eyes can see. When Galileo first looked up through his primitive little telescope he only saw about as much as we can see through an average pair of binoculars today and he managed to create history. Binoculars are well worth remembering when it comes to looking at the night sky. With binoculars the moon is fascinating through all the lunar phases and even Jupiter and the four moons that Galileo saw is quite possible. We won't go into great depth about which binoculars are better than others for night viewing because there are too many variables to be able to say which is better. Suffice to say, any binoculars will show you a lot more than you can see without them and wherever possible try to steady them with either a tripod (use tripod bracket to attach the binoculars to any standard tripod) or just lean against a fence or post. For those keen to explore the night sky we recommend that you check our large range of telescopes.
For more professional birdwatching, you may choose telescopes.
2) Birding
The most popular models for birdwatching are 7x40 and 7x50. They're small and nimble, offer steady hand-held views, and have sufficient light grasp to provide bright, well-resolved images. If you plan to study birds at close range, look for binoculars with a near-focus distance of a few feet. Of course, other factors should play into your buying decision, such as eye relief for use with eyeglasses, optical coatings, and mechanical construction.
For more professional birdwatching, you may choose spotting scopes.
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*** Which binocuolar to choose?


1) What do you need
For most people, you use a binocular for general purposes: spectator sports, sight seeing, etc. Except for some special activities, the most important criteria you need in choosing a binocular is portability and ease-of-use. If a salesperson tries to convince you otherwise, walk away.
The first specification we need to decide is magnification as indicated above. For all around purposes, 5x to 10x pretty much covers everything. It is a common mistake to assume that the higher the power, the more "powerful" your binocular is. The fact of the matter is you will be exhausted in a few seconds looking at the "dancing" image through a 15x binocular, unless you want to carry a tripod everywhere you go. Some opera glasses offer 2x and 3x power, but you definitely will not regret it if you take a regular 7x one with you instead. Another advice: never buy a zoom binocular! You may think it is useful to change the power of magnification, but it's cumbersome, difficult to use, and easily broken.
The second number is the Aperture of the objective lens. In a 7x50 binocular, the objective lens diameter is 50 mm. It is true that the larger the objective lens you have, the more light you gather from the object you are viewing. However, a larger objective lens also means a longer and heavy binocular body. So, you need to balance portability and lens size. I have boxes of binocular samples from manufacturers, but I find myself usually put a 7x50 or a 12x42 compact binocular in my pocket before leaving home.
There is also a practical limit on the size of the objective lens. This is determined by the exit pupil of a binocular. For a 7x50 binocular, divide 50 mm (objective lens size) by 7 (power of magnification) gives 5 mm, which is the size of the exit pupil. If you want to take full advantage of a large objective lens, i.e., to collect all the light funneled through the binocular, the binocular's exit pupil cannot be larger than your eye's entrance pupil (you know, the black hole at the center of your eyeball). This is where the limit comes in. The entrance pupil of a human eye changes with the light condition, but the maximum size is limited by age. The entrance pupil can reach 8 mm for a teenage, but is only ~4 mm for a 50 year old. For an entrance pupil of 5 mm, a 7x40 is just as good as a 7x50, but the latter is much heavier.
Of course, there are special needs. For example, experienced bird watchers prefer a 40 or 42, even 50mm objective lens to gather more light and see more details in deep shadow. A mariner likes our 7x50 because it is more forgiving when the deck is constantly moving.
2) Where to buy
Most people buy their binoculars from camera stores, discount department stores, and sports/hunting stores. The truth is that none of these stores is specialized in binoculars and the salesperson usually knows nothing about binoculars, except what is printed on the box. It is ok to buy from these places but you should be prepared to do your own Quality Check and know what you need. Some mail order firms tend to be specialized in binoculars and they usually carry most common brand names. But make sure they have a return policy, because you cannot see what you are buying on the phone. A good mail order business should allow a 30 day trial period.
Here is a common myth about brand names. Many people tend to believe that German brands and now some Japanese brands offer the best quality. But, is it worth 10 times the price just for the name? Here is some news you may find shocking: recently I visited several other large optics factories and found that these factories make most of the common brand names we know. As a matter of fact, these different brand names often come from the same production line. The only difference is the label! Unless you want to pay $800 for a binocular with the ultimate quality, the difference between common brands is negligible.
3) Quality Check
When you have a binocular in your hands, you can do a few simple tests to determine the quality. Remember: do not be fooled by the external appearance or the high price tag. A good binocular should pass several basic tests:
(a) Collimation
collimation refers to the alignment of the optical axis. The best performance is reached when the optical axis of the objective lens passes through the optical center of all lenses and prisms. This should hold true for both optical barrel assemblies. For most binoculars, poor collimation is not immediately obvious when you first pick it up and view through it. This is because your eyeball will adjust to compensate for misalignment in the optical instrument. Of course, if you let your eye muscle strain like this for a few minutes, you will feel the pain soon. Here is a simple way to check for collimation. First, look at a target ~100 yards away with the binocular. Be sure to adjust the center focus as well as the right eye piece. Now, relax your eye for a minute by taking the binocular down. Look at the target again with the left objective lens blocked by your hand. After a minute, quick;y remove your hand which covers the objective lens. If the target appears to be out of focus immediately but becomes in focus after a second or two, the binocular is not collimated. Your eye is doing the hard work to adjust collimation and focus. Choose a different binocular.
(b) Resolution
resolution determines how sharp the image is and how much fine detail you can see. You can usually check this by comparing a few different binoculars and look at the same target ~100 yards away. The manufacturer usually specifies resolution by a number, e.g., 5 seconds of arc. This means that the binocular should be able to resolve two fine features at an angle of 5" apart. Professionals use standard test charts very much like the one used in an eye doctor's office. You usually do not need to bother with this kind of tests, unless you are talking about a $1000 instrument. These test charts are available in the references I cited earlier. But, your common sense is sufficient for most purposes.
(c) Star test
the ultimate test of an optical instrument is the so called "star test". This is done by looking at the image of a distant star in the night sky. To do this, locate a bright star at the center of the field-of-view. The perfect image should appear as a round disk, with a few weak, concentric rings due to diffraction. Almost all binoculars will show some deviation from this perfect image. Some asymmetry is acceptable, but if your binocular's star test yields an image which is something like a triangle or a stick, try to get ride of it.
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*** more knowledge and review about spotting scope, please see it
 

 

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