The Formatt HD Neutral Density (ND) 0.6 Crown Schott-Desag B270 optical glass filter was specially formulated following extensive research into A.C.T. molecular dye applications. The filters offer a more neutral grey without the specular effects of particulate coatings found in current neutral density and graduated neutral density filters, allowing the user more precise control.nnHD technology was designed for today's filmmakers and videographers using the latest ultra-sharp cameras and lenses.nnFormatt, a company with three generations of experience in professional filter manufacturing, produces each filter to the highest technical standards. The finest materials, combined with cutting-edge production technology, have resulted in a level of optical excellence unmatched elsewhere.nnn- Formatt's solid and graduated HD neutral density filters are available in all popular screw-on round sizes and all standard square sizesn- All Formatt filters feature a unique edge frame offering maximum protection against chipping, surface scratching and allowing easy handling and cleaningn- With the filter description on top of the frame, filter identification is also much easier, especially when filters are stored in cases on locationn- Formatt HD neutral density filters have the same densities and light stops as Kodak Wratten standardsn- Formatt neutral density filters are a response to many directors of photography and filmmakers who feel it is important to shoot with the widest aperture possible to minimise depth of field, particularly with HDnnnNeutral density filters have four main usesnn- To enable the use of slow shutter speeds, particularly with high-speed films, to record the motion of subjects such as waterfalls, clouds or carsn- To decrease depth of field by allowing the use of wider apertures, which helps to separate subjects from their backgroundn- To decrease the effective ISO of high-speed films (above 400 ISO) and allow their use outdoors in bright situationsn- To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes that could cause overexposurennnNeutral density factorsnn- ND.3 (exposure adjustment = 1 stop, reduces ISO by 1/2)n- ND.6 (exposure adjustment = 2 stops, reduces ISO by 1/4)n- ND.9 (exposure adjustment = 3 stops, reduces ISO by 1/8)n- ND1.2 (exposure adjustment = 4 stops, reduces ISO by 1/16)