Saturday, April 2, 2011

How to Choose Good Night Vision Binoculars


    * Q.How are binoculars labeled?
    * A.The typical binocular is labeled with two numbers, for example 8x40, 7x35 and so on. A few binoculars use three numbers as in 10-20x50. These are zoom binoculars.

    * Q.What does the first number in a binocular mean, such as the 8 in 8x40?
    * A.The first number - the 8 in an 8x40 or 8 in an 8x25 - is the magnification. Magnification simply means how many times the image is enlarged over normal when you look through the binocular. Another way to think of magnification is how many times closer the subject appears to be in a binocular than it actually is. An 8x40mm, then, with 8x magnification, makes the subject appear to be eight times larger or, to look at it the other way, eight times closer than it really is. An 8x50, 8x40, 8x20 are all 8x binoculars and all magnify an identical 8x.

      In a zoom binocular, the first two numbers out of three, represent the zoom range. In a 7-15x40, for instance, you can change the magnification from 7x up to 15x.

      Choose this first number carefully - more is not always better and this is especially true of magnification. As magnification goes up, image brightness goes down, field of view (the amount of territory seen through the binocular) goes down and, just as importantly, image steadiness also goes down. In fact, image steadiness is the limiting factor on how much magnification can be used in a handheld binocular. This is because a binocular magnifies not only the image, but also every shake and tremble in your hands. In general, most people find that a 10x binocular is the highest magnification that can be comfortably steadied without a support. Anything higher than a first number of 10x requires additional support, usually in the form of a tripod.

    * Q.What does the second number in a binocular mean, such as the 40 in 8x40?
    * A.The second number in a binocular - the 40 in 8x40 or 25 in an 8x25 - is the diameter (width) of each front lens, measured in millimeters. This number directly affects performance. When magnification and quality is equal, the larger the second binocular number, the brighter the image as well as the sharper the image. An 8x40, then, will produce a brighter and sharper image than an 8x25, even though both enlarge the image an identical eight times. The larger front lenses in the 8x40 also produce wider beams of light (exit pupil) that leave the eyepieces. This makes it more comfortable to view with an 8x40 than an 8x25.

      On the other hand, the larger front lenses in the 8x40 binocular also make the 8x40 bigger and heavier than the 8x25 binocular. An 8x25 may not be optically as good as an 8x40, but its smaller size makes it a better traveling companion. Remember, a compact binocular will outperform any full size binocular left at home or in the car because it was too heavy to carry.

      By the way, the second number is not the field of view as many people mistakenly believe, nor does it affect the field of view.


    * Q.What is the field of view?
    * A.Field of view is the amount of territory you see when you look through the binocular. Imagine a fence 1000yards away. If a binocular has a field of view of 372 feet at 1000 yards, you will see 372 feet of the fence. If the field of view is 250 feet at 1000 yards, you will 250 feet of fence.

    * Q.What determines the field of view in a binocular?
    * A.Field of view is determined by two things. First is magnification. In general, as magnification goes up, field of view goes down. A 10x will show more detail in that fence at 1000 yards than an 8x, but it will not show you as wide a section of fence. The second thing that determines field of view in a binocular is the eyepiece design. Wide-angle design eyepieces of good optical quality, however, are expensive. Inexpensive binoculars with wide angle eyepieces are usually not as sharp as standard binoculars.

      Note: The second binocular number IS NOT the field of view as many people mistakenly believe. An 8x25 binocular can have as wide a field of view as an 8x50 binocular. Lastly, a difference in field of view of 30 feet at 1000 yards in a binocular may sound like a lot, but out in the field, it is not really significant.


    * Q.What is exit pupil?
    * A.The exit pupil in a binocular is the actual width of the beam of light that leaves the eyepieces and is measured in millimeters. To see an exit pupil, hold the binocular at arms length and you will see a circle of light in each eyepiece. This circle is the exit pupil. To calculate the size of the exit pupil, divide the first binocular number into the second binocular number. A 10x50, 7x35, and 8x40 all have an exit pupil of 5

    * Q.What does exit pupil tell you about a binocular?
    * A.Exit pupil is a very rough guide to image brightness. Binoculars with large exit pupils provide brighter images under very low light conditions. For normal daylight viewing, an exit pupil of 2.5 or 3 is fine. For astronomy, an exit pupil of 5-7mm is preferred. An exit pupil larger than 7 is a waste of light since the human eye cannot open wide enough to accept an exit pupil larger than this. Exit pupil should not be taken too literally, since it treats all binoculars, regardless of lens coatings and optical quality as if they are the same.

      A+ large exit pupil does have other uses, however. A large exit pupil is easier to keep centered on the eye and this is an advantage when it is difficult to hold a binocular steady, as on the deck of a moving boat. That's why a 7x50 with an exit pupil of 7+ has always been the traditional marine binocular.

    * Q.What is relative brightness (RE)?
    * A.Relative brightness, like exit pupil, is a rough guide to image brightness. It is simply exit pupil squared, so a binocular with an exit pupil of 5mm will have an RE of 25. As with exit pupil, relative brightness should not be taken too literally, since it treats all binoculars, regardless of lens coatings and optical quality as if they are the same. In actual tests, some premium grade compacts with a low relative brightness are actually brighter than some full size binoculars.

    * Q.What is twilight factor?
    * A.This is a mathematical formula that predicts the mount of detail that can be seen in low light. Twilight factor is the square root of magnification times objective. A 10x40 will have a twilight factor of 20 (square root of 10x40). As with exit pupil and relative brightness, twilight factor should not be taken too literally, since it treats all binoculars, regardless of lens coatings and optical quality as if they are the same. No $50 binocular will ever equal a premium grade binocular for low light detail, even though they both have the same exit pupil.


    * Question: What is a prism?
    * AA prism of the left upright on the eyes, the image is used to generate the appropriate authority is a glass element. If prism binocular will generate an image upside down. Binoculars are using two kinds of prisms. Polo is a prism, a roof prism, the other is called a dog.

    * Question: What is the prism polo?
    * AA Polo prism binoculars and other optical devices used in the prism is an old style. Polo roof prism prism prism volume is greater than the volume of the body so that Polo prism binoculars tend to be. Polo, you always eye can recognize the shape of a prism. Polo prism binoculars are always offset eyepiece lens front are not linear. However, Polo is a very efficient optical prism. Roof prisms are more expensive than the next good. This quality polo prism roof prism optical quality in every bit as good as the nunedoepnida a much lower cost. $ 200 to you, especially the eyes of the dollars you want to search for the best optics, polo prism, is your best choice.

    * Question: What is a roof prism?
    * AA Roof prism roof prism is small, the shape of a small house. Roof prism size and shape of the main advantages are. It is more compact than the prism Polo Polo less than a prism can be installed on smart casing. This is better to keep a roof prism for the most people to handle both eyes are my eyes. You always recognize the shape of the roof prism can be. Roof prism binoculars eyepiece lens, the front is always a straight line or straight.

      Far below the roof prism, a prism and a good polo expensive to by the same light. In fact, all the roof prisms are created equal. Roof prism optically clear modification phase (PC) and light roof prism (a prism of light on the mirror are losing Polo) is a silver-coated mirrors. Distribution is much more important roof prism prism.

      Loop, the exact location of the prism required for the alignment may have a useful side effect. Roof prisms are securely housed in cages instead of focusing mechanism, such as many polo prism binoculars are usually in the external eye. This is a good roof prism binoculars prism firmer and smoother than the average polo nunedoepnida focus.

    * Questions or BK7 Bak4 is?
    * A. They are used as optical glass prisms of binoculars are the ratings. All quality binoculars are used Bak4. Cheap binoculars just below the glass BK7 are using it for.

Lens Coatings

    * What is a lens coating?
    * A light and lens coating to the image of the chemical is coated IOL. Whenever the light hit the lens, the light is a constant rate of loss. Half of the incident light lens coating without losing a lot of eyes are used in the eyes because the lens.

    * Q: What do you have the eye lens coating is used?
    Fully multi-coated multi-coat all courts: * lens coating used on the eyes leading category is 3 A: No.

    * What is a "completely covered the eye," What is.
    * AA "full coat" coating spherical binocular lens coating lens has at least efficient - Fault magnesium fluoride. This type of lens coating can be found only in expensive multi-coated binoculars binoculars does not create an image's brightness.

    * What is a "multi-coat your eyes," What is.
    * A portable binoculars and the best lens is the multiple layers of coatings, specialty chemicals. This format is a multi-coating coated, most of it through the lens of the light can be. Mutli-coated lenses, but all eyes are a "multi-coat" is displayed as part of a trademark "fully shielded" my eyes are brighter than.

    * Q What is the perfect multi-coating the eye?
    Koto Maru Chi * AA all lenses and eye "fully multi-coat," and the FMC is shown. It's all coating systems to produce a brighter image. All quality binoculars "All multi-coat" is.


    * Eyes focused on what the concentration is?
    * AA central focus of both eyes focus on objects is one of the wheels. In general, it is the most universal use around the eye system is very far from being close to all the objects you can focus on.

    * Question the individual eyeglass (IF) focusing on the eyes, what is it?
    * A focus on the individual eyepiece eyes when you see the object, once 40 yards away to infinity in time for your eyes and focus attention on objects that require additional focus may need to focus on each eyeglasses. This is a good system for medium-and long-distance object, it is not suitable for near work. The most common marine binoculars binoculars, telescopes, if found by.

    * What "no focus" or question the eye "free focus"?
    * A. It is, however, the economic version of each eye is the focus of the eyepiece of the eyeglasses is locked in a factory can not be adjusted. This forty yards away from a focus on near objects, but not, it is also the right eye and two eyes can adjust the intensity difference between oenjjoknun no means are meant to. Most of an eye a little bit stronger than others, because this is a major drawback for most people.

Diopter adjustment

    * Try adjusting binocular response is?
    * Try adjusting binocular you, oenjjoknun right eye can compensate for the difference in intensity during the A: No.. Most people, first, because a stronger than others, the ability of the model, "focusing on freedom" can be found in all but the binoculars.

    * Q. Where attempts to adjust the binoculars?
    * A attempts to adjust the reach that the traditionally upper-right eyeglasses, and other wheel, and many models today are using sentahokaseunoburotku mechanism.

Interpupillary distance

    * Questions binocular interpupillary distance (IP address) What is it?
    * A distance between the pupil and the pupil is the distance between the eyes. All binoculars can be opened wide to meet the tight deadline different widths, but a very small face or a problem with people properly, they need to find them the right eye facing large.

Close Focus / Closest

    * Q "Closest", or in my eyes, "close focus" is?
    * A "The Closest" or in the eyes focus on the object closest to the "close focus" than the street near my eyes do not focus on. This feature is important for birds, some applicationssuch.


    * Question: What is binocular eye protectors?
    * A and ahyirerihu, your eyes, eyeglasses may be in sight yet to see the full is the maximum distance. Your eyes go far beyond this distance reduces the field if the view is displayed. Larry boy and then the glass is closer to the eyepiece to prevent their eyes when the eyes to watch for people wearing glasses is a major concern.

    Yes, I wear glasses, many ahyirerihu nuneulbogo If you need to do?
    Very thin plastic lenses of your glasses and a small face, and if the minimum is usually 14 or 15 mm is considered, * A, you just may be obtained as 13 mm. You are using a thick glass lens and glasses case, to find a model that more children after Larry says is an area of ​​17-20 mm.

    * Binocular Eye Cup, "AC" position, and eye glasses, the "exit" position must do?
    * A is to wear glasses, "AC" position when not wearing glasses on the "down" position, please put the cup on the child. Old-style folding binoculars with rubber baby kat not spray is the most modern binoculars, "said Twist," and achieved child star kat not spray the "full".


    * Eyes, my throat is a lot of weight you can carry Q. How?
    * And A. Most of the people much better than 35 ounces in less than 30 ounces of your neck comfortably carry much weight that you will find something. Binocular your neck pain is the weight on your shoulders now, but support your neck in my eyes, I want to see the harness if possible.


    * What is your question? Waterproof Eye?
    * AA waterproof binoculars moisture in the eyes (without any blurring of the two eyes may be) for the fog is to be secured by the manufacturer. Binocular waterproof fogproof (FCM), the charge will be made by nitrogen and eyes. Water, climate change prevention, prevention, non-waterproof as there is no guarantee that a different label.

    * Q. Waterproof binoculars do I need?
    * A case of water surrounding the use of the eyes from the harsh conditions to use it must be waterproofed. Despite a more casual use, the more sealed waterproof binoculars and then enters the eye of the dirt and dust, easy-to-eye at the onset of the problem.


    * What is a binocular armor question?
    * A rubber or other synthetic materials the armored eye binocular housing is covered by. The exterior of both eyes, the binoculars are not waterproof, but it does not protect you from injury, more comfortable, to keep your eyes and forehead on something by mistake "quiets" makes.


    * Q. I can mount on a tripod with your eyes?
    It is adaptive triangulation? If the display as a tripod adapter threading * A. Yes, your eyes can be mounted on a tripod. If it is listed as an adaptive triangulation, including some large binoculars and have these accessories, you may still need to buy a tripod adapter.

    * Q. Binoculars Tripod where adaptation?
    * A. It is usually a folding binoculars are often hidden beneath the hinged lid is located in front of the Department.

    * How should I attach to the tripod eyes?
    * A magnification of the binoculars 10 times or 12 times more stable on a tripod in the image whenever there is a need to connect to my eyes. In addition, 70 mm or more usually requires a tripod to support your weight and the heavier the binoculars is the last number.


    * The most popular size and functionality for each application will be:
    * Hunt: Water, 8x40, 8x42, 10x40, 10x42 roof prism
    * Birds and Wildlife: 8x40, 8x42, 10x40, or less than 15 feet near the center of a 10x42 roof prism or polo
    * Astronomy a tripod: 10x70, 20x80, 25x100 and
    * Sea: waterproof 7x50
    * Sports: 8x40 or 8x42
    * Hiking: 8x25, 10x25 and compression

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