This filter is purely designed to reduce the amount of light entering the lens without affecting the colour tones ie a neutral colour shift. Particularly useful in strong light and high contrast situations for example snow or Mediterranean beach scenes where the camcorder"s auto exposure can be operating out of its normal range. It can also be used to force a slower shutter speed for creative effects.An ND4 filter is equivalent to 2 f stops and an ND8 filter to 3 f stops