polaroidfiltre

Polaroidfilter, or polarizing filter, is an optical device that transmits only light with a specific polarization while blocking light with the orthogonal polarization. By suppressing reflections from non-metallic surfaces and increasing color saturation and contrast, polarizing filters are widely used in photography, cinematography, and surveying.

The concept was developed in the early 20th century and was commercialized by the Polaroid Corporation, founded by Edwin H. Land in 1937. The term Polaroid has become closely associated with polarizing filters, although many manufacturers produce similar polarizers. In practice, two main designs are used: linear polarizers and circular polarizers. Linear polarizers pass one polarization orientation; circular polarizers combine a linear polarizer with a quarter-wave plate to produce circularly polarized light, which helps camera metering and autofocus systems function correctly.

Rotating the filter changes the amount of light transmitted, typically reducing exposure by about 1–2 stops and sometimes more at strong polarizing settings. This rotation also controls glare and color saturation, enabling deeper blue skies, crisper foliage, and reduced reflections on water, glass, or wet surfaces.

Applications and limitations: In photography and cinematography, polaroidfilters are favored for reducing glare from water, glass, and shiny backgrounds and for enhancing color contrast. They are less effective for metallic reflections and can complicate viewing through LCD screens due to polarization. They also reduce overall light, so exposure adjustments are usually required.

See also polarizer; polarizing filter.