After the filter is mounted on the lens, turning the filter ring between “Min” and “Max” can greatly control the amount of light entering the lens. With the Hoya Variable Density filter, it’s possible to shoot with fast lenses in full sun for a very shallow depth of field or to slow down the shutter speed to where the shutter can be open for several seconds in full sunlight.
The filter varies from 1.5 to 9 stops with a twist of the filter.
The Hoya Variable Density filter uses high-quality optical glass from Hoya Corporation, the world’s largest optical glass manufacturer and is available in sizes 52mm to 82mm.
For best results, it’s recommended to use a tripod when photographing with slow shutter speeds.