ND Filters for Your Drone - How They Work and Which Ones ... DJI has three official ND filters for their drones: ND4, ND8, and ND16. The number associated with an ND filter indicates that how much light enters the lens in terms of a fraction. ND4 reduces light by 1/4. An ND4 filter can reduce 2 stops of light, allowing you to slow the shutter speed from 1/100s to 1/25s.