From the ManufacturerProtect Your Lens while Reducing UV ExposureThis UV Filter blocks the invisible Ultra Violet component of light from the sky, which can cause blur and to which many color films react with a blue cast. These filters should be called UV-Blocking Filters, because there are filters for technical applications that pass UV radiation and block all the other wavelengths. Nevertheless, the short term “UV Filter” has become established among photographers. 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. It is recommended for analog color and black-and-white as well as digital photography. Coated to Improve Image QualityEach glass surface is vacuum coated with one layer of Anti-Reflection coating. This single layer helps to prevent internal ghosting and reflections. It also improves light transmission from approximately 92% (uncoated glass) to over 98%. Side view of Slim LineMount. Click for larger view. Slim Line Filter MountThis filter uses our Slim-Line mount made of brass for wide angle lenses. They do not have a front accessory thread to avoid vignetting with lenses as wide as 17mm in 35mm format. Some photographers report success with lenses as wide as 16mm. A slip on cap is supplied.This filter amazingly has a height of only 3mm.Product DescriptionHigh Quality German Filters