This 3-stop Drop-In K-Series ND and Circular Polarizer Filter from H&Y Filters combines a solid neutral density effect with a circular polarizer effect. It is made specifically to fit between a separately available H&Y Filters 100mm K-Series Filter Holder and one of the filter holder's adapter rings. Its 0.9 optical density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. By slowing your exposure time, you can create images with motion blur or by opening up your aperture to create shallow depth of field.

Simultaneously, this filter can help 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 polarizing filter arranges and 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 plane in addition to the linear polarizing filter. The addition of this quarter wave plane is to circularly polarize the linearly polarized light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polarizer, auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarized, it permits the use of these functions.

Drop-In K-Series Neutral Density 0.9 and Circular Polarizer Filters are constructed from Schott B270 glass for increased optical clarity and color fidelity. They are mounted within a geared aluminum-alloy filter ring assembly with an external dial, which allows for the independent rotation of the filter in order to adjust the intensity of its polarization effect. Each side of this filter includes eight layers of anti-reflection coating to prevent internal ghosting and reflections as well as an anti-smear nano coating for an improved beading effect when in contact with water or oil for greater cleaning efficiency.

• Drop-in neutral density and circular polarizer filter for a separately available H&Y Filters 100mm K-Series Filter Holder
• 0.9 neutral density filter darkens the image, allowing you to photograph with a longer shutter speed or wider aperture than normally required
• Providing a 3-stop exposure reduction, this filter allows you to control depth of field and convey movement more easily
• Polarizing filter effect arranges, and filters, directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of the light
• Helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface
• Clears up haze in distant landscapes and provides more saturated, vivid colors
• Strongest polarization effect when used at a 90° angle from the sun
• Circular polarizer effect is ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features
• Each glass surface includes eight layers of anti-reflection coatings to prevent internal ghosting and reflections as well as an anti-smear nano coating for an improved beading effect when in contact with water or oil for greater cleaning efficiency
• Constructed from Schott B270 glass for increased optical clarity
• Filter pouch for storage and transport