The Hoya 49mm alpha 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 non-coated and has approximately 96% average light transmission. It is constructed from optical glass and precision milled aluminium frames.
- 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.
- Approximately 96% average light transmission.
- 3 to 4x filter factor reduces exposure by 1.6 to 2 stops.
- Constructed from optical glass and precision milled aluminium frames.
- Plastic filter case for storage and transport.
|Filter Factor||3 to 4 (1.6 to 2 stops)|
|Effect||Eliminates reflections and haze and improves colour and tonal saturation|
|Front Filter Thread Size||49 mm|
|Front Lens Cap Size||49 mm|