Sigma 105mm WR Circular-Polariser Filter

The Sigma 105mm WR (Water Repellent) Circular Polariser Filter helps to reduce reflections and glare by filtering out light that has become polarised due to reflection from a non-metallic surface. The light from the sun naturally becomes partially polarised due to reflecting off electrons in air molecules, causing the light to scatter into what appears as haze. A polarising filter arranges, and filters, this directionally polarised 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 polariser only differs from a linear polariser in that it contains a quarter wave plane in addition to the linear polarising filter. The addition of this quarter wave plane is to circularly polarise the linearly polarised light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polariser, auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarised, it permits the use of these functions.

This filter is multi-coated to eliminate internal ghosting and reflections. An anti-static coating serves to limit the accumulation of static electricity, making dust particles easier to remove or preventing them from adhering to the filter. Additionally, a water-repellent coating results in an improved beading effect when in contact with water, as well as oil, for greater cleaning efficiency while enhancing scratch resistance.

Sigma WR Circular Polariser filters are constructed from optical glass with a black rim. Set within an aluminum-alloy filter ring that can be rotated in order to adjust the intensity of the polarization effect, the glass provides increased clarity as well as colour fidelity while the black rim further ensures that reflections do not occur along the filter's edge.

• Helps to reduce reflections and glare by filtering out light that has become polarised due to reflection from a non-metallic surface.
• Polarising filters arrange, and filter, directionally polarised light perpendicularly to the reflected light, allowing for the absorption of much of the light.
• Clears up haze in distant landscapes and provides more saturated, vivid colours.
• Strongest effect when used at a 90° angle from the sun.
• Circular polarisers are ideal for use with digital cameras and autofocus lenses where a linear polariser will often disrupt auto exposure and focus features.
• Multi-coated to help eliminate internal ghosting and reflections.
• Anti-static coating serves to limit the accumulation of static electricity, making dust particles easier to remove or preventing them from adhering to the filter.
• Water repellent coating results in an improved beading effect when in contact with water, as well as oil, for greater cleaning efficiency while enhancing scratch resistance.
• 1.25 to 1.4x filter factor reduces exposure by 0.3 to 0.5 stops.
• Constructed from clear, optical glass with a black rim which further ensures that reflections do not occur along the filter's edge.
• Aluminum-alloy filter ring is durable while remaining lightweight.
• Filter ring can be rotated to adjust the intensity of the polarization effect.
• Knurled front edges provide a more textured grip when mounting or removing it from a lens.
• 105mm front filter threads allow for use with other filters.
• Plastic filter case for storage and transport.