How to choose sunglasses
Most people buying yourself sunglasses, guided by the idea that this is just a fashion accessory, and all points are different from each other by the color of the lenses (which does not matter), and the name of the manufacturer. In fact, it's much more difficult.
Any, whether sun or regular glasses consist of two main components - lenses and frames. It is this element points to the purchase pridela focus. Important components of the rim are also considered bow and nose pads. In order to choose a 'right' sunglasses, on each of these elements need to know more.
And so, the lens - this is the main optical element of sunglasses. They perform basic functions: protect the eyes from UV and solar radiation. The lenses are glass or plastic. And they both have their advantages and disadvantages.
Glasses with glass lenses are less safe as can easily be broken, cracked. However, their fragments can get into the eyes or cut the skin around the eyes. Points with such lenses are not suitable for people who move a lot, active lifestyle. In addition, the glasses with glass lenses are much heavier than similar plastic. More weight makes the glasses less comfortable. Another disadvantage of glass lenses is that they are often fogged up. The advantage of plastic over glass lenses is the higher of their abrasion resistance (glass lenses harder to scratch).
Plastic (polycarbonate) lenses are more popular nowadays. They are lighter, so the man in glasses with these lenses feel more comfortable. Plastic lenses are much stronger than glass. They certainly can be broken, but above this it is necessary to work hard. Coming out of this, plastic lenses can be considered more secure. That's why children need to buy glasses with plastic lenses it. Compared with glass lenses, polycarbonate has only one drawback - they are relatively easy to scratch.
Not be amiss to say that the producers as glass and plastic lenses is constantly innovating their product. Today it is sold sunglasses with impact-resistant glass lenses and plastic lenses, which have a high abrasion resistance. So the choice of material from which the lens will be made for you.
lenses for sunglasses are not only material from which they are made. They also have different light transmission, which also affects the color. Depending on the ability of all of the sunglasses are divided into 5 categories. Points of the first category (indicated as 0) is passed from 80 to 100% Svetlov rays, the second (1) - 43-80%, the third (2) - 18-43%, fourth (3) - 8-18% fifth (4 ) - 3-8%. Information about the light transmission lens is presented, usually in a foreign language, but, nevertheless, the buyer should know the value of numbers (0,1,2,3,4) and understand what he needs glasses.
lenses of different colors also have different characteristics. Thus, black lenses are considered neutral, they retain the natural color. Brown and blue lenses distort color slightly, but improves contrast. Green lenses used in eyeglasses for people who suffer from glaucoma. Purple and pink lenses are most often used just for beauty.
Lenses can be coated with Polaroid and mirror coating. Polarized lenses reduce visual interference from the glitter of water and other smooth surfaces. Mirror coating discourages sunlight (not UV).
Rim sunglasses also need due attention to the side-chapels. It may be made of a metal alloy, plastic or nylon. Sturdy metal frames. Eyeglasses made of nylon is used for sports glasses, they are flexible, lightweight and does not break. Very often it is used, metal frames, Redshaw - plastic. Plastic structure, compared with metal, less robust, easier to break. Nose pads should be soft, the bow should not press into the temples and behind the ears.
Buy Sunglasses need in a safe place - in optics. There, you will not be deceived, help, prompt, provide you with all the information you need.