The above recommendations only, not absolute, can also be based on their own wallets and preferences, choose a higher or lower level also does not matter. In addition to the Abbe number now control is good, Zeiss lenses, after all, Cai Si is the founder of Abbe number of glasses invented by the Carl Zeiss Company to control the Abbe number is also reflected in the ultra low dispersion lens on high quality. However, even if the control is better, the Abbe number of the index will not be more than 5, so it is difficult to detect such a small gap in cheap fake oakley sunglasses the actual use, so Zeiss lenses are the first choice for the wallets and drums.

Lens material is not as many as glass frames, mainly glass and resin lenses

Resins are now commonly available in PC lenses and ordinary resin lenses

PC is polycarbonate, I introduced PC material of the frame in the first frame, polycarbonate density is only 1.2 grams per cubic centimeter, 57% lighter than glass lenses, resin lenses than ordinary light 37%, its toughness is very strong, not easily broken, large thickness of PC was used to make bulletproof glass and the space shuttle watching the windows and the space suit (also called space mask plate, sheet, very suitable for the universe) love children and activists. Plus its high refractive index, so PC lenses can be made very thin. In addition PC fake oakley sunglasses lens itself has anti UV ability, it does not need to prevent 100% UV coated glass like that Bullet proof glass, do you know the bulletproof glass in front of Obama is actually the same kind of material as your glasses?

But PC also has disadvantages, because does not have the strength of glass, so do not wear, need coating to ensure long time use, and the glass texture is soft, easy deformation force, not suitable for plastic frames and rimless (the experience also introduced rimless lenses is directly affected by the force), refraction high rate also led to a low Abbe number (usually around 32), the dispersion is relatively large. But generally speaking, PC is the most suitable material for most eyeglass lenses.

The film series universe Yishilu Yishilu

Ordinary resin lenses generally refer to the United States CR-39 resin lenses. Abbe number is cheap oakley sunglasses relatively high, the dispersion is relatively small, the density of PC is slightly higher than 1.32 g / cm3, but still much lighter than the glass, not easily broken, even if broken will not produce sharp points, but the refractive index is relatively low, generally around 1.5, so a relatively thick lens.

PMMA is organic glass material, we often say, the refractive index is around 1.49 and Abbe number around 57, density and PC lens is about 1.2 grams per cubic centimeter, the biggest feature is broken will not have sharp corners, not easy to hurt the body, but because of the heat deformation, bad wear-resistance mainly used in industry,glasses with a relatively small.

Glass lenses The glass lens is the earliest use of glasses, the relatively hard texture, not easy deformation, not easy to change, compared to PC resin and is not easy to scratch, by adding different material change glass refraction rate, ordinary glass refractive index is about 1.523, higher than the CR-90, so the ordinary glass lenses CR-90 thin, cheap fake oakleys such as glass above the coordinates on the map, BaF, BaK on behalf of glass with different material, glass lenses now can make the index up to 2, of course, so the high refractive index of the dispersion is very serious, so it is difficult to see the 2 lenses, the highest common it's 1.9.

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