Polarizing filter for photography
Polarizing filter allows light to pass through it in a "polarized" way. A radiation of light ray is composed of waves of certain length, (wave length), vibrating around its axis. When a filter of polarizing material is introduced in the path of the light, the light passes through it in one plane, and it is "polarized." Quality, color temperature or nature of the light will not change in this case, but the intensity of light is slightly reduce.
In nature, any reflection is normally polarized. The light coming from reflections of water or glass, is vibrating in a restricted single plane. Now if a polarize material is introduced in the path of light, it will block the light when it is set perpendicular to the plane, in which the reflected light is vibrating.
This means that when we are shooting a showcase, glass in front of the showcase, which is throwing unwanted reflections, can be made invisible. If we put a polarize filter on the camera lens and rotate till its polarizing lines are perpendicular to the plane, in which the reflected light is vibrating, it will block the light and unwanted reflection vanishes.
Polarize works at certain angles and are useful in blocking flares. Effects of this filter is dramatic as it cuts off reflections, darkens the sky and improves overall color saturation and contrast. This filter has a filter factor, so we have to over expose the exposure by the recommendation of the manufacturer.
If we put two polarize filters, it can work as variable neutral density filter, as it blocks the light completely when two of them are set at perpendicular to each other. Then by rotating, slowly the opacity is reduced and more light will pass.
There are two types of polarized filters, linear and circular. Both gives the same result but a linear filter will interfere with auto-focus ability of the camera lens, whereas circular filter has no such issue.
Apart from neutral density filter, this is the only filter which is required in digital photography.
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