Introduction: Neutral Density filter evenly reduce the amount of light passing through the lens without effecting color. Ideal for reducing bright light in large aperture situations when a narrow depth is field is needed. Neutral Density Filters are often used to achieve motion blur effects with slow shutter speeds High Quality Optical Glass Increases control of depth of field Eliminates overly bright, washed-out images. Balances exposures Equally effective in color or black and white photography Includes Filter Case Specification: Model: Haida ND Frame Profile: 3.1mm Filter Density: Optional Double Threaded: Yes Optical Material: B270 Quality Optical Glass Neutral Density, Exposure Adjustment, Light Transmission ND0.9 (8x), 3 stops, reduces ISO by 1/8, 12.5% ND1.8 (64x), 6 stops, reduces ISO by 1/64, 1.0% ND3.0 (1000x), 10 stops, 0.1% Neutral Density Filters Have Four Main Uses: 1, To enable slow shutter speeds to be used, especially with high speed ISOs, to record movement in subjects such as waterfalls, clouds, or cars. 2, To decrease depth of field by allowing wider apertures to be used, this helps separate subjects from their background. 3, To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situation. 4, To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes, this could cause over-exposure.