The 72mm Ice CaNDi-5 Combination Solid ND and Circular Polarizer Filter combines a solid neutral density effect with a circular polarizer effect. When in use, this filter's 32x filter factor provides a 5-stop exposure reduction. Its 1.5 optical density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed without overexposing your image. By slowing your exposure time, you can create motion blur for special effects or to convey a sense of movement. Opening your iris allows you to create shallow depth of field, which can help isolate your subject.
Simultaneously, this filter can help to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. The light from the sun naturally becomes partially polarized due to reflecting off electrons in air molecules, causing the light to scatter into what appears as haze. A polarizer filters this directionally polarized 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 polarizer only differs from a linear polarizer in that it contains a quarter wave retarder in addition to the linear polarizing filter. The addition of this quarter wave retarder re-randomizes the polarized light, so it will work with auto focus and exposure functions, which can function poorly when a linear and not a cirular polariaer is used.
This filter is constructed from optical glass for clarity as well as color fidelity and features an aluminum alloy filter ring that can be rotated in order to adjust the intensity of the polarization effect.