The 39mm Power XND Mark II Variable ND 0.3 to 2.1 Filter from Aurora Aperture is a variable neutral density filter that is designed to mount onto lenses with 39mm front filter threads and provides an exposure reduction of 1 to 7 stops. Its 0.3 to 2.1 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. The degree of density is easily controlled by rotating the front filter ring, helping you to predetermine the additional exposure length required. By increasing your aperture or slowing your exposure time, you are able to control depth of field and convey movement more easily. For easier, repeatable control over density settings, the front ring is visually demarcated with dots representing different density values.
This filter is constructed from Schott B270 glass for increased optical clarity as well as color fidelity, and each glass surface is multi-coated to prevent ghosting as well as reflections. The nano coating associated with the 39mm Power XND Mark II Variable Neutral Density 0.3 to 2.1 Filter provides an additional layer that allows for more efficient cleaning when its surfaces come in contact with dust, dirt, water, or oil.