Polarisationsfilter

Polarisationsfilter, also known as a polarizing filter, is a photographic lens accessory that reduces reflections and enhances color saturation by filtering light according to its polarization. It consists of a rotating sheet or film of polarizing material mounted in a ring that attaches to the lens.

The filter works by transmitting only light with a specific polarization orientation. By rotating the filter, the photographer adjusts the amount of polarization in the transmitted light, thereby controlling glare from non-metallic surfaces such as water, glass, and wet leaves, while increasing contrast and sky blue.

There are two main types used in photography: linear polarizers and circular polarizers. Linear polarizers transmit linearly polarized light but can interfere with modern camera metering and autofocus. Circular polarizers include a quarter-wave plate that converts the linearly polarized light into circular polarization, avoiding such issues and remaining compatible with most cameras and autofocus systems. Both types are rotatable to achieve the desired effect.

Typical applications include landscape photography, water scenes, and foliage where glare and reflections are problematic. The filter can also deepen blue skies and intensify saturation, but it reduces overall light by about 1 to 2.5 stops, depending on quality and angle.

Limitations and considerations include reduced light transmission, potential vignetting with ultra-wide lenses when used at strong polarizing settings, and diminished effectiveness indoors or on overcast days. Proper use involves rotating the filter while observing the scene to optimize glare reduction and color enhancement. Polarising filters come in various diameters and coatings to suit different lenses.