The B+W 39mm XS-Pro MRC-Nano 803 ND 0.9 Filter (3-Stop) is a neutral density filter with a 8x filter factor that provides a 3-stop exposure reduction. Its 0.9 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. By increasing your aperture or slowing your exposure time, you can control depth of field and convey movement more easily. Neutral density filters do not affect the coloration of the image and are ideal for pairing with other filters.
To prevent internal ghosting and reflections, each glass surface includes multiple layers of anti-reflection coating. This Multi-Resistant Coating (MRC) also offers greater protection to the filter substrate and helps it to stay clean for longer than with uncoated filters. The Nano coating associated with XS-Pro filters provides an additional eighth layer over the MRC, resulting in an improved beading effect when in contact with water for greater cleaning efficiency.
B+W filters are constructed from SCHOTT glass for increased optical clarity and color fidelity. This filter features a thin brass filter ring to minimize the potential for vignetting while enhancing durability and preventing jamming. To further reduce the possibility of vignetting when this filter is in use, the filter ring's outside diameter is slightly larger than the actual thread size. This may prevent the use of some lens manufacturer bayonet hoods.