5. Anti-fouling ability In recent years, many brand lenses has shifted their direction of research from increasing hardness and increasing light transmittance to increasing the smoothness of the lens to improve its ability of water and grease resistance. The most representative lens is the Zeiss lotus film series. Test Method - We can wipe the lens clean and drop a drop of water and move it back and forth on the lens. If the lens is always a water droplet, it proves that it is good waterproof. If the water droplets are all spread out on the surface of the lens, the function is relatively poor. 6. Anti-UV ability, anti-radiation ability, anti-blue light ability Let me talk about anti-UV first. Anti-UV lenses are UV resistant lenses. It can completely absorb or reflect the most harmful ultraviolet rays to the human eye to protect the eyes. The UV resistance coefficient is expressed by the UV value: the most preferred is UV400, which is generally UV375. Optical sho...