The 4.5" Round 0.9 Neutral Density (ND) Filter from Tiffen has several uses and offers the possibility to achieve otherwise impossible results. It allows the photographer to adjust exposure without affecting colour balance. ND filters appear grey and reduce the amount of light reaching either the sensor of a digital camera or the film plane of a traditional camera. Neutral density filters are used to create unusual special effects such as capturing the "blur" of water rippling in a waterfall or the swirling effect of city traffic.nnTiffen's ColorCore glass is produced through a process that involves permanently laminating the filter material between two pieces of optical glass polished to tolerances of one ten-thousandth of an inch, then mounting them in precision aluminium rings. Determining which neutral density filter gives ideal results for a given lighting situation requires knowledge, experience and a collection of such filters.nnNeutral density filters have four main usesnn- Allow the use of slow shutter speeds, particularly with high-speed films, to record movement of subjects such as waterfalls, clouds or carsn- Decrease depth of field by allowing the use of wider apertures, which helps separate subjects from their backgroundn- Decrease the effective ISO of high-speed films (above 400 ISO) and allow their use outdoors in bright situationsn- Allow cinema and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes that could cause overexposurennColorCore Technologynn- Tiffen filters are manufactured using ColorCore technology, a closely guarded exclusive process that involves permanently laminating the filter material between two pieces of optical glass polished to tolerances of one ten-thousandth of an inch, then mounting them in precision metal ringsn- The ColorCore process allows Tiffen to control the colour and density of their filters, as well as the characteristics of special effects filters with precision far superior to typical mass-tinted filters, which generally exhibit colour and density variationsnnSuperior Qualitynn- Major Hollywood film studios rely on Tiffen filters for their multi-million pound productions. Superior quality and design make Tiffen the go-to choice for filmmakers, professional photographers and even NASAn- Tiffen has also received an Emmy from the Academy of Television Arts and Sciences for its engineering excellencennSpecifications:nn- Type: Neutral density filtern- Size: 4.5" roundn- Grade: 0.9n- Filter factor: 3 stopsn- Effect: For using high ISOs in bright lightn- Application: Nature, travel, outdoor photographyn- Construction: ColorCore glass