The Hoya 49mm HRT Circular-Polariser UV Filter is designed to block ultraviolet light and reduce the bluish cast of daylight while also helping to eliminate 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 filter with polarising capability 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 offers approximately 98% average light transmission due to its High-Rate Transparency polarising film. It is constructed from optical glass and precision milled aluminium frames.
- Blocks UV light and reduces bluish cast of daylight.
- Helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface.
- Polarizing filters arrange, and filter, directionally polarized 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 colors.
- Strongest effect when used at a 90° angle from the sun.
- Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features.
- High-Rate Transparency polarizing film helps provide approximately 98% average light transmission.
- 2.5 to 2.8x filter factor reduces exposure by 1.3 to 1.5 stops.
- Constructed from optical glass and precision milled aluminum frames.
- Plastic filter case for storage and transport.