From the ManufacturerProtect Your Lens while Reducing UV Exposure (486M)This B+W Interference Filter has a completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MRC coating. It does not block by means of absorption, but by interference of the unwanted UV and IR radiation that is repeatedly reflected between these layers, affecting the wavelengths on both sides of the visible spectrum with a steep cut-off. It is used mainly on digital and video cameras with CCD sensors without an integrated IR protection filter, because the IR sensitivity of the CCD sensor would otherwise cause color changes and unsharpness. That unsharpness results from the chromatic aberration of the lenses that are only corrected for visible light. In the visible range, the transmission curve is very high and straight. This filter is completely clear and it requires no increase in exposure. It has a filter factor of 1. Important Note Regarding Wide-Angle LensesPlease note however that, in contrast to mass-colored (integrally colored) filter glass, the UV/IR Cut MRC (486M) filter is based on thin-film technology. More than 30 interference coatings are vapor-deposited on one side, while the opposite side is MRC-coated. In wide-angle lenses, the laws of physics lead to shallower incidence angles for peripheral rays. For geometric reasons these rays have to travel further through the interference coatings than rays traveling vertically through the coatings in the center of the lens. With increasing angle of incidence, this leads to a change in light color towards blue. This effect can clearly be seen by looking at an UV-IR barrier filter from an angle. The color of the reflected light changes, with a similar effect on the light traveling through the filter. The filter is therefore not suitable for lens systems with an angle of view greater than 60°. 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. MRC - A Special Scratch-Resistant, Water and Dirt Repelling CoatingThe left half of this filter has atraditional coating. The right halfhas 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 waterto 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 e