Polarizing filters

What is polarized light?

With polarized light, the electric field of the light oscillates in only one direction, such as up and down. It is therefore linear and can be referred to as linear polarization. However, most of the light we find in nature, such as sunlight or the light from a light bulb, is unpolarized and the electric field oscillates in many directions at once. This can cause problems in photography - such as unwanted reflections.

What is a polarizing filter and how does it work?

A polarizing filter helps you to suppress or emphasize reflections on non-metallic planes and thus achieve the desired photo quality. It accomplishes this by filtering out only one direction of this unpolarized light. Such a polarizer absorbs complementary polarizing light instead of reflecting it.

Light rays oscillating in the "wrong" plane can thus be suppressed. While linear polarizing filters were also widely used in the past, today the technology of circular polarizing filters has largely prevailed. A circular polarizing filter consists of two polarizing filter foils lying directly behind each other. A "true" circular polarizing filter produces circularly polarized light directly from unpolarized light.

Special polarizing filters

Usually, color changes are not desired with a circular polarizing filter. However, there are special polarizing filters that can filter out some of the blue light, for example. This so-called Warming Polarizer works like a combination of a polarizing filter and a light yellow filter. Red, yellow and green colors are emphasized, giving the impression of a warmer image

Special polarizing filters can be used to emphasize light in certain colors. Depending on the setting of the filter and the direction of polarization, these are different contrasting colors. Images created with these filters show distinct color changes. These polarizing filters are available for the colors green and red as well as for yellow and blue. The yellow-and-blue filter is commonly known as the Gold-N-Blue filter and is used primarily in landscape photography. On cloudy days, you can use it to create artificial blue and yellow colors on a gray sky or body of water. The Red-Green filter, on the other hand, is used less often because it looks very artificial.

Range of application of the polarizing filter

A circular polarizing filter is simply screwed onto the threaded insert of your camera lens and works best when oriented 90? to the sun. For example, if you want to take photos on a lake or the ocean and suppress the reflections of the water, but at the same time intensify the blue of the sky and water, you can set this up with a polarizing filter for your camera.

In landscape photography, the polarizing filter is thus a must, especially when it comes to photographing bodies of water - still or flowing. By means of polarizing filters, contrasts can be created here that are difficult or impossible to achieve even through image processing. However, a polarizing filter can also be very useful outside of landscape photography, for example in wildlife photography with a long focal length. For example, if you want to photograph animals on the surface of water, a polarizing filter is an excellent choice. Often the animals do not stand out strongly enough from the water surface due to the reflection and are therefore difficult to recognize in photos. Using polarizing filters, you can turn down the contrast of the water, making it darker. Dolphins, whales, fish and other marine animals stand out better from the water surface as a result. However, a circular polarizing filter also helps you if you want to photograph foliage or forests. For example, it can suppress annoying blue or silvery reflections of the sky, and you can get a rich green out of your pictures.

A polarizing filter is also suitable for rainbows. Color lines of the rainbow are polarized light and are therefore suppressed with the correct polarization. So if you turn the polarizing filter to its extreme setting, no rainbow will be seen. If you now adjust the polarizing filter 90? from this position, more than half of the polarized light from the clouds around the rainbow will be absorbed and the rainbow will be almost completely transmitted. If you compare the rainbow to its surroundings, it looks much stronger. So by turning the polarizing filter, you can find the contrast that suits you.

Not only the quality of the polarizing filter film is crucial!

With the polarizing filter, you should pay attention to the workmanship and feel in order to be able to make the most precise adjustment possible. The polarizing film in itself already darkens the light. The second polarizing foil can change the darkness by turning it and that to the desired degree. This trick of polarization thus allows you to darken your image as you wish without distorting the light source. Here it is important that precise turning - without over-turning - is possible. With a high-quality polarizing filter, this can be adjusted with millimeter precision to achieve the optimal degree of reflection and contrast