PRODUCT HIGHLIGHTSnn- Filter factor of 1.25 to 1.4xn- +0.3 to 0.5 f-stopsn- Helps eliminate reflections and glaren- Reduces haze in landscapesn- Greater saturation of colours and tonesn- Black-rimmed, multi-coated optical glassn- Resistant to water, oil, static electricity and scratchesn- Slim aluminium alloy filter ringn- 77mm front filter threadn- Knurled front edge, plastic casennOverview of the Sigma AFG9C0nnThe Sigma 77mm WR (Water Resistant) Circular Polarizing Filter helps reduce reflections and glare by filtering out polarized light due to reflection on a non-metallic surface. Sunlight naturally becomes partially polarized when reflecting off electrons in air molecules, causing light scattering that appears as haze. A polarizing filter organises and filters this directionally polarized light perpendicular to the reflected light, allowing much of this light to be absorbed. This results in a noticeable reduction of reflections and glare on non-metallic surfaces and an increase in saturation of skies and vegetation.nnA circular polarizer differs from a linear polarizer only by the addition of a quarter-wave plane in addition to the linear polarizing filter. The addition of this quarter-wave plane serves to circularly polarize the linearly polarized light for use with autofocus and exposure functions. Due to the way light is broken down and filtered with a linear polarizer, the accuracy of autofocus and exposure becomes skewed during use. When light becomes circularly polarized, it allows the use of these functions.nnThis filter is multi-coated to eliminate internal ghosting and reflections. An anti-static coating serves to limit the build-up of static electricity, making it easier to remove dust particles or prevent them from adhering to the filter. Additionally, a water-repellent coating improves the beading effect when in contact with water, as well as oil, for better cleaning efficiency while improving scratch resistance. Sigma WR Circular Polarizing Filters are constructed of optical glass with a black edge. Mounted in an aluminium alloy filter ring that can be rotated to adjust the intensity of the polarization effect, the glass offers increased clarity as well as colour fidelity, while the black edge further ensures that no reflection occurs along the edge of the filter.nn- Helps reduce reflections and glare by filtering out polarized light due to reflection on a non-metallic surface.nn- Polarizing filters organise and filter directionally polarized light perpendicular to reflected light, allowing much of the light to be absorbed.nn- Eliminates haze in distant landscapes and provides more saturated and vivid colours.nn- Strongest effect when used at a 90° angle to the sun.nn- Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer often interferes with exposure and autofocus functions.nn- Multi-coated to help eliminate internal ghosting and reflections.nn- The anti-static coating serves to limit the build-up of static electricity, making it easier to remove dust particles or prevent them from adhering to the filter.nn- The water-repellent coating improves the beading effect when in contact with water, as well as oil, for better cleaning efficiency while improving scratch resistance.nn- The filter factor of 1.25 to 1.4x reduces exposure by 0.3 to 0.5 f-stops.nn- Constructed of clear optical glass with a black edge that further ensures no reflection occurs along the edge of the filter.nn- The slim aluminium alloy filter ring helps prevent vignetting and is durable while remaining lightweight.nn- The filter ring can be rotated to adjust the intensity of the polarization effect.nn- Knurled front edges provide a better grip when mounting or removing the filter from the lens.nn- The 77mm front thread allows use with other filters.nn- Plastic filter case for storage and transport.