Introduction and When to Use Polarizers

Polarized light can affect refracted light, light sources from the sun or light bulbs, and contains light from different directions. This kind of light is called non-refracted light, and light traveling in one direction is called linearly refracted light.

A polarizing film having tens of thousands of lattice structures is sealed in two glass slides of the polarizer. This strip-like structure is not visible to the naked eye. It only allows light rays traveling in a direction parallel to this stripe structure to pass through. Light perpendicular to this will be completely blocked, while light from other angles will be partially blocked.

When light passes through a plane, it forms refracted light. The degree of refraction varies depending on the refractive power of the reflective surface material. Take the water surface as its maximum refraction does not exceed 37 degrees, while glass is less than 32 degrees. Other surfaces such as wood, turf, plastic and painted surfaces also produce a certain amount of refracted light. The only untreated metal will be irregularly reflected.

Therefore, only by accurately grasping the refraction direction and correcting it, can the reflection phenomenon be completely eliminated. In other words, the projection angle of the light source should be close to the projection angle of the camera, and the maximum deflection angle should be between 30 and 40 degrees. To understand the effect of a polarizer, just rotate the filter’s front frame and you can see it from the viewfinder.

Both linearly polarized light and circularly polarized light include a linear polarizing film. However, there are the following differences in structure. The new monocular camera has a beam-splitting device that sends part of the light to the metering and sends another part of the light to the viewfinder.

If a linear polarizer film is added in front of the lens, for this system, it is equivalent to acting as a second polarizer, blocking light into the photometer, causing the photometer to get the wrong exposure (or aperture value). How much light is blocked depends on the angular density of the polarizer. Therefore, a polarizer is just a filter that allows only light from a specific direction to pass through.

A circular polarizer uses a polarizing film with 1/4 retarder film to solve this problem. Changing linearly refracted light to orbital propagation does not refract the photometric body. Therefore, a correct exposure value (aperture value) can be obtained.

Polarizers are used to capture landscape pictures and have a great influence on the description of clouds. Blue sky light has a higher refractive index than light scattered by white clouds. The use of polarizers can also saturate the colors of green leaves and eliminate fog when shooting urban scenes at low angles. The role of polarizers is that it is difficult to achieve the same effect by using post-production. As such, it is often one of the filters most players like to buy and use.

Polarizer type

Linear polarizer

Linear polarizer film is often used with manual or rangefinder cameras to increase color saturation and eliminate reflections. This light gray plane parallel-polarized material provides you with the best image rendering. The color filter index varies depending on the relative position of the sun, between 2.3 and 2.8. This filter is not recommended for digital cameras

Circular polarizer film (commonly known as CPL)

This color filter is specially designed for SLR cameras, digital cameras and digital video cameras, and can realize auto exposure and auto focus. It does not interfere with the metering system of these cameras. The color filter index is between 2.3 and 2.8.

Kasman polarizer

This advanced polarized lens is made of carefully selected polarizing film and optical glass. Its edges are glued and sealed, so it is still very durable in certain weather conditions. This kind of lens is also very suitable for those situations that require strict image quality. The polarizer is available in both linear and circular options. The color filter index is 2.3 to 2.8.

When to use polarizers

When shooting with natural scenery, using a polarizer can make the blue sky bluer and the white clouds more prominent. The effect is best when the angle of the sky and the angle of the sun are 90 degrees. Therefore, the effect of using a polarizer under backlight or forward light conditions is not significant. It is best to remove the polarizer when shooting against backlight to avoid glare. If the sky is gray when shooting, the polarizer cannot turn the sky blue. Also, depending on the light