This UV Filter blocks the invisible Ultra Violet component of light from the sky, which can cause blur and a blue cast. It should be called a UV-Blocking Filter, because there are filters for technical applications that pass UV radiation and block all the other wavelengths. UV Filters are ideal for photography in high altitudes (in the mountains), by the sea and in regions with very clean air. With the filter, the image gains brilliance and the disturbing blue casts are avoided. Because the glass is colourless, colour 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 colour and black-and-white as well, as digital photography.
Each 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%.
This filter uses the standard B+W F-Pro filter mount, which has a front accessory thread and is made of brass. Another advantage of the F-Pro mount is its modified retaining ring, which is no longer threaded in from the front, but holds the filter glass in place from the back. When removing a filter or lens hood that has been screwed on too tight to the filter, the retaining ring is not at risk of loosening.