Variable 0.3-1.5 Neutral Density Filter, Reduce Exposure by 1-5 Stops, Darkens Entire Image Area, Greater Control Over Exposure Settings, Allows Reduced Shutter Speed, Allows Wider Aperture, Multi-Coating and Resistance Coating, Optical Glass Construction, No. This 52mm Nano-X HD Variable ND2-32 Fader Waterproof & Scratch-Resistant Filter from K&F Concept is a variable neutral density filter with a range of 1 to 5 stops. The density can easily be continuously adjusted by rotating the knurled aluminum ring. Increasing exposure density allows the use of a wider aperture setting providing finer control over depth-of-field like increasing bokeh to help isolate the subject of an image. Increased density can also be used to lengthen shutter speed to enhance image blur as when shooting moving water. A variable density filter is also useful to control camera frame rates when shooting video.