Neutral density filters reduce the amount of light entering the lens on your camera. This enables you to use longer shutter speeds or wider apertures than would otherwise be possible in bright light situations. Neutral density filters are available in different strengths or grades. An ND2 filter cuts out 50% of light transmission (or 1 stop), an ND4 reduces light transmission by 2 stops and an ND8 filter cuts out 3 stops of light.
