Hitech 4 x 4" PROSTOP Neutral Density 3.0 Filter for the Lee Filter Holder

Advantages

Special edge gasket designed to prevent any light leakage that would contaminate the image

Allows you to use a much slower shutter speed or wider lens aperture

This filter will permit you to "blur" moving objects such as water, rivers, cars, etc

Increased exposure times open up a whole new vista of photographic potential

Absorbing Cell Technology

The secret to Formatt's consistency in filter design lies in its unique "Absorbing Cell Technology" (A.C.T.); this unique process allows color correct dyes to be applied to optically pure, wafer thin absorbing cells and offers a controllability that ensures the smoothest grad lines and consistent color across the whole filter surface

Hitech filters are made by Formatt, a company with three generations of professional filter-making experience produces every filter to the highest technical standards. The finest materials, together with state of-the-art production technology have resulted in a standard of optical excellence unmatched anywhere else

Neutral Density Filters Have Four Main Uses

To enable slow shutter speeds to be used, especially with high speed ISOs, to record movement in subjects such as waterfalls, clouds, or cars

To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background

To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situations

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