An ND filter, short for neutral density filter, is an essential tool for photographers looking to control the amount of light entering their camera. Unlike polarizing filters or graduated neutral density filters, which affect the quality of light, ND filters reduce the quantity of light without affecting its color or contrast.
ND filters are available in a range of densities, allowing photographers to fine-tune their exposure settings. They are particularly useful in situations where the photographer wants to use a wider aperture or slower shutter speed than would otherwise be possible. For example, ND filters can be used to create a shallow depth of field in bright sunlight or to capture motion blur in waterfalls or other moving subjects. ND filters also allow photographers to shoot at higher ISO settings without introducing excessive noise into their images.