on Wed 18-Jul-2012:
A good pair of ran ban sunglasses generally have several features:
Can prevent the ultraviolet radiation in sunlight. Certain amount of electromagnetic energy in a bunch of light waves, the wave size is to measure the wavelength, and inversely proportional to the energy and wavelength of the light wave, the shorter the wavelength, the higher the energy. In the visible violet energy, red energy minimization. Contains large amounts of ultraviolet light, natural light is due to the high energy of UV on the cornea and retina damage, so oakley sunglasses should block ultraviolet light.
To prevent light exposure. When the eye receives too much light, it will naturally shrink the iris, iris contraction to limit state, then people need to squint. If the light is still too much, such as snow reflected sunlight will be on the retinal damage. High-quality carrera sunglasses should be able to filter out a lot of pleasant to the eye light in order to avoid injury.
To prevent glare exposure. The unit of measure of the brightness or intensity of light lumens. Indoors, most artificial light intensity of 400-600 lumens. In the sunny outdoor brightness in a wide range of floating, the brightness of the shade is about 1000 lumens, such as large areas of concrete, the brightness of about 6000 lumens. Below 3500 lumens of brightness, we the human eye feel very comfortable. When direct light or reflected light to reach 4000 lumens brightness, the human eye receives light started to become difficult. When we try hard to see these very bright area, only to see the white flash, this is the glare.
Once the brightness to reach 10,000 lumens, the eye receives light is too strong and completely filtered light. Too long exposure to strong light can cause damage, leading to temporary or even permanent blindness. On a clear day, a large snow by reflected light brightness up to 12,000 lumens, if any protection right into, will cause "snow blindness".
Quality ran ban glass should be able to use polarized technology to completely eliminate such a glare.
Can eliminate specific frequencies of light. The people have a basic form of the two to see color. One kind is the object itself can emit a certain frequency of light, such as neon lights; another is reflected from objects of a certain frequency or frequencies of light, and absorb the light of other frequencies, these light waves mixed perception of a color light, such as coated paint objects to display color. Certain frequencies of light can blur the line of sight, and some other frequency light can enhance the contrast. For the cheap oakley sunglasses to select the right color can make it be more effective in certain circumstances.
The sunglasses lenses color lenses can absorb part of the light spectrum which can eliminate the blue part of the spectrum, such as yellow, which makes all objects appear bright and clear.
When to buy a discount oakley sunglasses, you may give up the above advantages, or even make it worse. For example, if your sunglasses do not provide UV protection, it is part of the light is filtered so that your iris to open to receive more light. This also would allow more ultraviolet radiation into the increases the damage of ultraviolet rays on the retina.