Polarizer
A filter that only allows light vibrating in a single plane to pass through it. It is possible to utilize it to further intensify the color of a particular portion of a photograph, such as the sky. It is also possible to utilize it to erase or diminish reflections on non-metallic surfaces, such as water or glass. This can be accomplished by using a special coating. In order to get the effect you want, you have to keep turning it while it's in front of the lens.
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