The Hoya Variable Density Filter is a solid variable density filter providing an exposure reduction of about 1.5 to 9 stops. The 1/3 to 1/400 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than would normally be required. The degree of density is easily controlled by rotating the front filter ring, allowing you to visualize the additional exposure length required. By slowing your exposure time or increasing your aperture, you are able to both control depth of field and amount of movement conveyed more easily.
This filter features a front rotating element that changes the density of the filter, to help reduce the amount of light entering the camera lens. It is constructed from high-quality optical glass from Hoya Corporation, with an aluminum filter ring.