They are the ideal filters for color and enhance contrast, removing reflections from water and glass or any surface that generates glare (impossible to do electronically) while adding rich and natural color saturation.
They are used to select what rays of light can enter the lens and remove unwanted reflections. By rotating the filter on the lens the light rays are polarized giving the water of rivers, seas or lakes, clouds with higher contrast and bluer skies. Linear polarizing filters are ideal for lenses with manual focus and exposure.
Polarizers are so versatile that they can even perform the opposite functions. Some filmmakers use polarizers to increase or improve reflections by simply turning the filter.
Polarizing filters are divided into linear and circular. A circular polarizing filter comprises of a linear polarizing filter plus another quarter wave or 90 degree delay filter. Ignoring more technical explanations, the output of a PL falsifies the measurements of the photometers and autofocuses of some reflex cameras. This does not happen with a circular polarizer, although at the cost of losing some quality since the light has to go through an additional filter . The observed result is practically the same between both types of filter, although there are tiny quality differences according to brands.
Schneider's True-Pol filter has an extinction ratio of ER 374, is 12 times more effective than other polarizing filters, being ideal for cameras with 4K capture.
The Tiffen Ultra Polarizer filter makes the polarization effect of a normal polarizer even more noticeable, obtaining more vivid and contrasting colors but having to compensate for exposure 1-2 / 3.