Description:*Neutral Density filters have several uses and offer the possibility of achieving otherwise impossible results. ND filters appear gray and reduce the amount of light reaching the film. ND filters also do not have an effect on color balance.Four main uses:1.Enables slow shutter speeds to be used, especially with high-speed films, allowing film to record movement in subjects such as waterfalls, clouds, or cars.2.Decrease depth of field by allowing wider apertures to be used, in turn helping to separate subjects from their background.3.Decrease the effective ISO of high-speed film (above ISO 400) and allow it to be used outdoors in bright situations.4.To allow picture and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes that can cause overexposure.*ND2:reduce one gear of the aperture,average transmittance of 50%*ND4:reduce two gear of the aperture,average transmittance of 25%*ND8:reduce three gear of the aperture,average transmittance of 12.5%Features: *100% brand new and high quality and cheap *Filter Thread Size: 30 mm *Filter Color: Black *Neutral Density Grade: *Made from High Quality Optical Glass *Reduces the light two f-stops *Increases control of depth of field. *Eliminates overly bright, washed-out images. Balances exposures *Equally effective in color or black and white photography.Package Contents :*1X 30 mm Neutral Density ND4 Filter