The Hoya Variable ND Filter uses two polarization layers to control the amount of light that passes through the filter and into the camera lens. At its minimum setting, the filter allows one-third of the light to pass through, which corresponds to 1.5 stops or shutter speed values. At its maximum, the filter only lets 1/400th of the light through, equating to 9 stops or shutter speed values.

Once the filter is mounted on the lens, rotating the filter ring between "Min" and "Max" allows for optimal control of the light entering the lens. With the Hoya variable density filter, it is possible to take photos with fast lenses like a 50mm f/1.4 at wide open aperture in full sunlight to achieve a very shallow depth of field. Alternatively, the shutter speed can be slowed down to achieve several seconds of exposure in bright sunlight. The longer exposure time can create motion blur effects, making it possible to achieve the popular effect where flowing water appears almost like fog. Almost any moving object can create a great impression of motion this way.

For content creators, ND filters are very helpful in setting shutter speeds to match frame rates while maintaining the depth of field of the footage.

The Hoya ND variable filter uses high-quality optical lenses from Hoya Corporation, the world's largest manufacturer of optical glass. It is available in diameters ranging from 52mm to 82mm. For best results, it is recommended to use a tripod when shooting with long exposure times.