If you have a high-end camera, the lens probably has screw threads, which means you can add a UV or Skylight filter (available at your neighborhood camera shop).

如果你有一架高档相机，那么它的镜头上可能有螺旋纹，这表明你能增加一个紫外或者天窗过滤器(附近的相机店里有售)。