The Formatt HD Neutral Density (ND) 0.9 Schott-Desag B270 Crown optical glass filter has been 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. HD technology has been designed for today's filmmakers and videographers using the latest ultra-sharp cameras and lenses. Formatt, 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. - Formatt HD Neutral Density filters, whether full or graduated, are available in all popular threaded round sizes and all standard square sizes - All Formatt filters are finished with a unique edge frame offering maximum protection against chipping, surface scratches and allowing easy handling and cleaning - With the filter description on top of the frame, filter identification is also much easier, particularly when filters are stored in cases on location - Formatt HD Neutral Density filters have the same densities and light stops as Kodak Wratten standards - Formatt's neutral density filters are a response to the many directors of photography and filmmakers who find it important to shoot with as wide an aperture as possible to minimise depth of field, particularly with HD Neutral density filters have four main uses - Enabling the use of slow shutter speeds, particularly with high-speed films, to record the movement of subjects such as waterfalls, clouds or cars - Decreasing depth of field by allowing the use of wider apertures, which helps separate subjects from their background - Decreasing the effective ISO of high-speed films (above 400 ISO) and allowing their use outdoors in bright situations - Allowing cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes that could cause overexposure Neutral density factors - ND.3 (exposure adjustment = 1 stop, reduces ISO by 1/2) - ND.6 (exposure adjustment = 2 stops, reduces ISO by 1/4) - ND.9 (exposure adjustment = 3 stops, reduces ISO by 1/8) - ND1.2 (exposure adjustment = 4 stops, reduces ISO by 1/16)