How to choose an effective lens

Glasses, how to correctly choose a suitable lens? Choose the lens is very important, the following details how to select Cheap Ray Bans lens.

Introduce 4 kinds of lens standard for your below:

1, glass lens

Glass lens with more scratch resistance characteristics than other material of the lens, but the relative to its weight is heavy, the relative refractive index: common tablets for 1.523, thin film: more than 1.72, up to a maximum of 2. Polymer resin lens: polymer resin lenses are lighter than glass lenses, impact resistance are not easy to break, but because of its relatively low hardness, so more prone to scratches than glass.

2, PC lens

There is also a material than the polymer resin more resistant to impact, often used in aviation equipment transparent windows, police on the mask, and the astronaut Helmet Mask, it is only about 1/10 the weight of glass, resin lenses compared with traditional is only half the weight.

General PC lens and scratch resistant protective film, in use will be enough to obtain better aging, Ray Ban Sunglasses lens is most used in children, goggles or athletes. PC lens also has an important characteristic, that is PC lens has isolated the harmful ultraviolet effect, but it also contains the surface scratches easily.

3, bifocal lens

Bifocal lenses can also Ciao Shenyang and near both visual acuity, mainly for correction required. The general distribution of bifocal lenses for: the upper portion of the glasses is far lower, the lens for viewing the near the point of use, as nearly with the fan size, it is considered nearly with the nature of the work order.

General flat double light by the use of the highest probability, they only a small region in the bottom of the lens as near the point of use, the lens periphery and the upper is used to gaze at the distant place and provide a good peripheral vision. The traditional bifocal lenses for the first double optical lenses, lens from the center is divided into two parts, that is less than half of all lenses as near point distance, they provide good wide near the point of view, for long time in the near point workers have a better effect, architects, accountant, artists and other nature of the work is close, this lens can reduce the chance of swinging head. Double optical lenses can also be used to, only need to close point reading correction, but in a near work and inconvenience of glasses will be taken take.

4, three focus lens

For those who need to distance vision person (generally about from 18 inches to six feet), as far and near, the use of trifocals lenses can meet this kind of demand, those in the computer or the cashier work, for the middle distance visual acuity has special demand, this lens can meet he worked on the visual demand.

The Cheap Ray Ban Sunglasses correction lens also comprises a plurality of range, is different in each piece of different distance between the lens the boundary is not obvious, the multiform lens line, may need to be in place, then they can see through the touch of a hand can feel, however, when the user in the conversion from near to far, eyes still feel very abrupt change.