Neutral Density filters have several uses and offer the possibility to achieve otherwise unachievable results. ND filters appear grey and reduce the amount of light reaching the film. They have no effect on colour balance. They have four main uses: 1) To enable slow shutter speeds to be used, especially with high speed films, to record movement in subjects such as waterfalls, clouds, or cars. 2) To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background. 3) To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situations. 4) To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure. Multicoated to minimise reflection at the filter surfaces which reduces flare and ghosting. Neutral Density factors: NDx2 (exposure adjustment = 1 stop, reduces ISO 1/2) NDx4 (exposure adjustment = 2 stops, reduces ISO 1/4) NDx8 (exposure adjustment = 3 stops, reduces ISO 1/8)
These popular filters are renowned for their ability to minimise reflection at the filter surfaces which reduces flare and ghosting. The result is an average light transmission of over 97%, giving sharp contrast and well balanced colour. HOYA HMC filter s are recommended for enhancing the performance of today's multicoated lenses.