Product Description This filter fulfills the desire of many photographers for pure lens protection without a filter effect. Its only function is to keep dirt, sand, or splashes away from the front lens. The extremely clear special glass with high transmission is MRC-finished. From the Manufacturer Clear Filters - Lens Protection with No Effect on Image Quality This filter fulfills the desire of many photographers for pure lens protection without any filter effect. Its only function is to keep dirt and moisture away from the front lens. Made from special, extremely clear optical glass, B+W Clear filters exhibit very high transmission values. MRC - A Special Scratch-Resistant, Water and Dirt Repelling Coating The left half of this filter has a traditional coating. The right half has MRC coating. The lens elements of high-quality lenses and the plano surfaces of filters require a perfect shape and smoothness to achieve the best optical quality. Dirt, greasy fingerprints, water marks and scratches reduce the image contrast and the sharpness, which can result in blooming at light sources and have an effect similar to a soft-focus lens. A clean front lens element and clean filter surfaces are therefore an absolute pre-requisite for demanding photographers. MRC coating causes the water to bead up and slide right off. The MRC coating is first and foremost a broadband anti-reflection coating. This means that its reflection-reducing effect, which is thus also a transmission-increasing effect, i.e. one which suppresses scattered light and ghost images and transmits more light, has a broadband action over the full spectrum. In contrast, the (almost always blue) single-layer coating only has a high effect in the medium wavelength range around yellow and yellow-green where the eye is most sensitive to light, while its effect is greatly reduced toward the blue-violet and purple-red end regions of the visible spectrum. With the MRC coating, this blue, violet and red to deep-red light cannot produce any contrast reducing scattered light, spotty reflections or ghost images. A broadband effect can only be achieved with a multilayer coating which requires a much higher effort and precision because unevenness and irregularities of the individual layers build up on one another and amplify one another. Schneider therefore uses a plasma-assisted evaporation coating process in which inert gas ions accelerated in an electrical field compact the material deposited on the lens surface in the vacuum chamber. For photographers, the main advantage of MRC coating, is it's ability to combat flare and ghosting. An added benefit is that their filters remain free of dirt longer, so that they do not have to be cleaned so often. When cleaning the filter does become necessary, it is a lot easier to wipe off the dirt with a blower brush, because of MRC's ability to repel dirt and moisture. This also reduces the risk of micro-scratches which can occur during cleaning. Side view of F-Pro Mount. F-Pro Brass Filter Mount This filter uses our standard B+W F-Pro filter mount, which has a front accessory thread and is made of brass. Compared to the earlier standard mount, the F-Pro mount, introduced in 2001, has become thinner. Now it can be used with wide angle lenses, including most 24mm focal lengths on a full frame body, without vignetting. 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.