Freewell Magnetic ND Filter and Polarizer Filter, 8x Filter Factor, 3-Stop, Darkens Entire Image, Reduce Shutter Speeds, Widen Apertures, Greater Control over Exposure Settings, Helps to Eliminate Reflections and Glare, Reduces Haze in Landscapes, Greater Color and Tonal Saturation, UV Filter/Magnetic Lens Adapter Ring, Fits Lenses with 82mm Filter Threads, This Freewell 82mm Magnetic Quick-Swap Neutral Density 0.9 and Circular Polarizer Filter is a filter that combines a solid neutral density effect with a circular polarizer effect. When in use this filter's 8x filter factor provides a 3-stop exposure reduction. Its 0.9 density creates a darkening of the entire image allowing you to photograph with a wider aperture or slower 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. Simultaneously this filter can help to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. The light from the sun naturally becomes partially polarized due to reflecting off electrons in air molecules causing the light to scatter into what appears as haze. A polarizing filter arranges and filters this directionally polarized light perpendicularly to the reflected light allowing for the absorption of much of this light. This results in a noticeable reduction of glare and reflections from non-metallic surfaces and an increase in the saturation of skies and foliage. A circular polarizer only differs from a linear polarizer in that it contains a quarter wave plane in addition to the linear polarizing filter. The addition of this quarter wave plane is to circularly polarize the linearly polarized light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polarizer auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarized it permits the use of these functions. An included Freewell 82mm UV Filter allows the neutral density and circular polarizer filter to be used on a lens with 82mm front filter threads. Each surface of the Freewell 82mm Magnetic Quick-Swap Neutral Density 0.9 and Circular Polarizer Filter and the Freewell 82mm UV Filter is multi-coated to help eliminate internal ghosting and reflections. The Freewell 82mm Magnetic Quick-Swap Neutral Density 0.9 and Circular Polarizer Filter and the Freewell 82mm UV Filter are also coated for resistance to oil dust and scratches offering greater protection to the filters and helping them to stay clean for longer than with uncoated filters. The coatings are also hydrophobic resulting in an improved beading effect when in contact with water for greater cleaning efficiency. The Freewell 82mm Magnetic Quick-Swap Neutral Density 0.9 and Circular Polarizer Filter also includes 82mm front threads permitting the use of screw-on filters with 82mm rear threads., FW-82-ND8/PL FW82ND8PL