This UV filter blocks the invisible UV component of light from the sky, which can cause blur and to which many color films react with a blue cast. UV filters are ideal for photography in high altitudes (in the mountains), by the sea and in regions with very clean air. The pictures gain brilliance and disturbing blue casts are avoided. Because the glass is colorless, color rendition is not altered, aside from the elimination of the unwanted blue cast, and no increase in exposure is required. That makes a UV filter very suitable as protection of the front element of the taking lens against dust, flying sand, sea water spray and the like, and it can be kept on the lens at all times.