The Hoya 49mm HD3 Circular Polarizer Filter 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.
While providing over 92% light transmission, 8 layers of anti-reflection nano coatings on each side, for a total of 16 layers, are applied to the Hoya 49mm HD3 Circular Polarizer Filter. These coatings offer a high degree of protection to the filter substrate and help it to stay clean for longer than uncoated filters. The nano coating formula associated with HD3 Circular Polarizer filters results in an improved beading effect when in contact with water for greater cleaning efficiency and is also effective with regard to oil and stains while also helping to prevent scratches.