An ND (Neutral Density) filter is a type of filter that reduces the amount of light entering a camera lens, allowing the photographer to use slower shutterEither mechanical and/or electronic shutters are possible. Mechanical systems can use a leaf (or iris) shutter or curtain shutter. In digital cameras a third alternative is also possible: the electronic shutter. This works by activating and then deactivating the CCD so that no further light can be recorded, regardless of whether light is hitting the CCD. The shutter controls the exposure time, which can range from thousandths of a second to several minutes or more. Fast shutter speeds freeze action, slow speeds are more suited to stationary subjects. A tripod is recommended for slow exposure shots to avoid camera shake, or IBIS. More speeds or wider apertures in bright conditions without overexposing the image. ND filters are commonly used in landscape photography to create long exposureThe amount of light that reaches the film (or camera sensor). It determines how light or dark an image is. The exposure of an image is determined by the aperture, shutter speed, and film speed (ISO). During exposure, the sensors or chemicals on the film in analogue models, are subjected to the light outside the camera for a certain time. More effects, such as smooth water and blurred motion. Some cameras such as the Canon G series (see Canon G12 and XZ1) have a built in ND filter.
