PRODUCT FEATURES - Filter factor of 1.25 to 1.4x - +0.3 to 0.5 stop - Helps eliminate reflections and glare - Reduces haze in landscapes - Increases saturation and colour tones - Multi-coated optical glass with black mount - Water, oil, static electricity and scratch resistant - Aluminium alloy filter mount - Front thread for 105 mm filter - Knurled front edge, plastic case Introducing the Sigma AFK9C0 Sigma's 105 mm 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 directionally polarised light perpendicularly to the reflected light, allowing much of that light to be absorbed. The result is a notable reduction in reflections and glare on non-metallic surfaces and an increase in saturation in skies and foliage. 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 serves to circularly polarise the linearly polarised light 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 is impaired during use. When light becomes circularly polarised, it allows the use of these functions. This filter is multi-coated to eliminate ghosting and internal reflections. An antistatic coating serves to limit the build-up of static electricity, making it easier to remove dust particles or preventing them from adhering to the filter. In addition, a water-repellent coating enhances the beading effect upon contact with water, as well as oil, for improved cleaning efficiency while enhancing scratch resistance. Sigma's WR Circular Polarising Filters are made from optical glass with a black mount. Mounted in an aluminium alloy filter ring that can be rotated to adjust the intensity of the polarising effect, the glass offers increased clarity and colour fidelity, while the black mount 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 directionally polarised light perpendicularly to the reflected light, allowing much 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 antistatic coating serves to limit the build-up of static electricity, making it easier to remove dust particles or preventing them from adhering to the filter. - The water-repellent coating enhances the beading effect upon contact with water, as well as oil, for improved cleaning efficiency while enhancing scratch resistance. - The filter factor of 1.25 to 1.4x reduces exposure by 0.3 to 0.5 stop. - Made from clear optical glass with a black mount that further ensures that no reflections occur along the edge of the filter. - The aluminium alloy filter ring is durable while remaining lightweight. - The filter ring can be rotated to adjust the intensity of the polarising effect. - Knurled front edges provide a better grip when mounting or removing the filter from the lens. - The 105 mm front thread allows use with other filters. - Plastic filter case for storage and transport.