PRODUCT FEATURES - Filter factor from 1.25 to 1.4x - +0.3 to 0.5 stops - Helps eliminate reflections and glare - Reduces haze in landscapes Overview of the Sigma AFE9C0 The Sigma 67mm WR (Water Resistant) circular polarising filter helps reduce reflections and glare by filtering polarised light caused by reflection off a non-metallic surface. Sunlight naturally becomes partially polarised when it reflects off the electrons in air molecules, causing light to scatter as haze. A polarising filter organises and filters this polarised light directionally perpendicular to the reflected light, allowing a large portion of this light to be absorbed. This results in a notable reduction of reflections and glare on non-metallic surfaces and an increase in the saturation of skies and vegetation. A circular polariser differs from a linear polariser only by the addition of a quarter-wave plate in addition to the linear polarising filter. The addition of this quarter-wave plate allows linearly polarised light to be circularly polarised for use with autofocus and exposure functions. Due to the way light is broken down and filtered with a linear polariser, the accuracy of autofocus and exposure becomes biased when used. When light becomes circularly polarised, it allows the use of these functions. This filter is multi-coated to eliminate ghosting and internal reflections. An anti-static coating serves to limit the build-up of static electricity, thereby facilitating the removal of dust particles or preventing them from adhering to the filter. Additionally, a hydrophobic coating enhances the beading effect on contact with water, as well as oil, for better cleaning efficiency while improving scratch resistance. Sigma WR circular polarising filters are constructed from optical glass with a black rim. Placed in an aluminium alloy filter ring that can be rotated to adjust the intensity of the polarising effect, the glass offers increased clarity as well as colour fidelity, while the black rim further ensures that no reflections occur along the edge of the filter. - Helps reduce reflections and glare by filtering polarised light caused by reflection off a non-metallic surface. - Polarising filters organise and filter polarised light directionally perpendicular to the reflected light, allowing a large portion of the light to be absorbed. - Eliminates haze in distant landscapes and provides more saturated and vivid colours. - Strongest effect when used at a 90° angle to the sun. - Circular polarisers are ideal for use with digital cameras and autofocus lenses where a linear polariser often interferes with automatic exposure and autofocus functions. - Multi-coated to help eliminate ghosting and internal reflections. - The anti-static coating serves to limit the build-up of static electricity, thereby facilitating the removal of dust particles or preventing them from adhering to the filter. - The hydrophobic coating enhances the beading effect on contact with water, as well as oil, for better cleaning efficiency while improving scratch resistance. - The filter factor of 1.25 to 1.4x reduces exposure by 0.3 to 0.5 stops. - Constructed from clear optical glass with a black rim that further ensures that no reflections occur along the edge of the filter. - The thin aluminium alloy filter ring helps prevent vignetting and is durable while remaining lightweight. - The filter ring can be rotated to adjust the intensity of the polarising effect. - Front knurled edges provide a better grip when mounting or removing the filter from the lens. - The 67mm front thread allows use with other filters. - Plastic case for storing and transporting the filter.