This Tiffen 4 x 5.65" Circular Polarizer Filter is designed for use within the Tiffen Multi Rota Tray. When configured with a separately available Tiffen 138mm Circular Polarizer Filter for Tiffen Multi Rota Tray, a solid variable neutral density filter effect can be obtained. To control the degree of density, the tray provides the ability to rotate the 138mm circular polarizer, providing an exposure reduction of 2 to 6 stops. Alternatively, this filter may be used by itself as a circular polarizer within the Tiffen Multi Rota Tray. It can then help 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.