The 49mm Sion Slim Circular Polarizer Filter from Vu Filters 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.
Sion Slim circular polarizer filters are multi-coated, have approximately a greater than 85% average light transmission, and are constructed from Schott glass with a black rim. Set within aluminum-alloy filter rings that are durable while remaining lightweight, the glass elements provide increased clarity as well as color fidelity, while their black rims further ensure that reflections do not occur along the filter's edge. The Flat Wave Overcoat associated with this Sion Slim circular polarizer filter provides an additional layer over the multi-coatings, resulting in an improved beading effect to repel water for greater cleaning efficiency.
This 49mm Sion Slim Circular Polarizer Filter's ring assembly is 3.4mm thick, to help maximize vignetting prevention. It can be rotated in order to adjust the intensity of the polarization effect, and features side knurling to provide a more textured grip for mounting or removing the filter from a lens.