Haida Red-Diamond M15 Magnetic 20-Stop Round Filter NanoPro ND6.0 filter is a neutral density filter with a 1000000x filter factor. This 6.0 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or longer shutter speed than normally required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. these Ultra filters receive an additional lapping and polishing process during production to ensure lower reflectivity ad improved clarity and sharpness. Neutral density filters are intended to not affect the coloration of the image and are ideal for pairing with other filters. Nano coating provides an improved beading effect with water or oil for more efficient cleaning. the filter is not only for long exposure but for shooting the sun.