The Veydra 138mm Unmounted Circular Polarizer Filter is designed for use within a Veydra 4 x 5.65 / 138mm Revar Cine Rota-Tray. It helps 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.To prevent internal ghosting and reflections, each glass surface includes 16 layers of anti-reflection coating. These coatings also offer greater protection to the filter substrate and help it to stay clean for longer than with uncoated filters. This filter is constructed from Schott glass for increased optical clarity as well as color fidelity. When it is placed within a 4 x 5.65 / 138mm Revar Cine Rota-Tray, it can be used along with a Veydra 4 x 5.65 Linear Polarizer Filter within a top-loading, two-tray matte box. Both the Veydra 138mm Unmounted Circular Polarizer Filter and a Veydra 4 x 5.65 Linear Polarizer Filter can then work together to provide the effect of a solid variable neutral density filter that features an exposure reduction of approximately 2 to 8 stops.Helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface.Unmounted for use in a Veydra 4 x 5.65 / 138mm Revar Cine Rota-Tray.Polarizing filters arrange, and filter, directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of the light.Clears up haze in distant landscapes and provides more saturated, vivid colors.Strongest effect when used at a 90? angle from the sun.Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features.Multi-coated with 16 layers of anti-reflection coating on each glass surface.4x filter factor reduces exposure by 2 stops.Constructed from Schott glass for optical clarity.When placed within a 4 x 5.65 / 138mm Revar Cine Rota-Tray, can be used along with a Veydra 4 x 5.65 Linear Polarizer Filter within a top-loading, two-tray matte box to provide the effect of a solid variable neutral density filter that features an exposure reduction of approximately 2 to 8 stops.