UV filter,as we known,the primary function of them are used for absorbing the ultraviolet light below 400 nm wavelength. Because the UV filters contain lead, it can absorb the ultraviolet light,and it is heavier than other same size glass. 
  UV filters applied to the seaside, mountains, snow, and open areas such as the shooting environment and can weaken due to UV-induced blue hue. At the same time, a digital camera, for example, ultraviolet light can also rule out the possibility of interference of the CCD to enhance clarity and color effects.
  Also the UV filter can protect the delicate and valuable lens.It stop your lens being scratching and dust.