The Hoya 77mm Pro-1 Digital ND8 Filter reduces the amount of light entering the lens by 3 f/stops, allowing wider apertures to be selected, which is perfect for portraiture to reduce depth of field. Subject appears crisp & clear while the background becomes a soft blur. Alternatively, the ND8 Filter can be used to allow longer shutter exposures than would otherwise be possible & is widely used for subjects such as waterfalls & other nature scenes to blur the moving elements & emphasize the movement.