The polarizing filter has a special place in the arsenal of optical filters photographer. If the color of the filter blocks the light primarily with a certain wavelength, polarization filter stops light radiation of a wavelength that can pass between a plan and the plan varies in the vertical oscillations.
The filter consists of an optical connection and a skeleton together. Optical track is made of special material with the polarizing filter (special synthetic materialMicrocrystalline as "Polaroid"). Skeleton with two rings: one fixed, with screw connection or bayonet mounted to the target ("MOS"), and secondly, randalinat, the filter is mounted and can rotate freely, to set a filter to obtain the maximum effect .
The natural light, as usual, and any artificial light source, has properties of both waves and particles (photons). Feature is the perpendicular vibration of the tree to the propagation direction (vector variation) in all plans:left-right and top to bottom and all intermediate positions, in order to treat the section, all possible vectors of the diameter of a circle swing.
The circumstances of polarized light: blue sky (in a good amount determined - by means of refraction of light passing through different layers of the air), surface water, glass, plastics, paints and various surfaces of lakes, etc. covered.
Which filter is best, circular or linear?
If you use a standard filter, linear polarization ispossible problems with auto-focus functions, and have automatic exposure - the apparatus with these features.
It 'also possible that classical devices (with TTL meters), some anomalies in the exposure calculation. Why? When the optical path of breaking these features glass prisms or mirrors, the light is polarized in a plane in a dependent relationship cos (alpha) are mitigated, and the more the angle of incidence is near the Brewster angle.
ACircular Polarizer is a linear polarizing filter and used directly behind a plate of birefringent material put together. Birefringent material - like cellophane - transparent to light soon in some directions than in others, due to its anisotropic structure, which leads to different refractive indices are delayed, the direction with maximum speed and minimum ironing fast and slow axis, respectively , and called at 90 degrees. Sheet thickness is calculated so thatcontributes to a quarter wavelength (quarter Q, which is 90 degrees, light green, as a rule, the most sensitive to the human eye).
Why unwanted reflections occur, even when using a polarizing filter?
The reflected light - non-metallic surface is polarized to a degree. The degree of polarization depends on the angle of incidence and refractive index of the two environments. In an angle (Brewster angle), the light is completely polarized at different angles, the polarization is onlypartially. Brewster angle value is approximately 55 degrees to the current (water bottle). If a place to sit polarizing filter on the approval of your target and at an angle of approx. 55 degrees on the shop window by a rotation proper polarizing filter will stop most of the reflections.
When should not I with the polarizing filter?
In the absence of polarized light, a polarizing filter is not simply a neutral density filter, exposure to 1-2-tier (or more). Ifthe light that you look a little ', that this filter leads to a prolongation of the exposure, and you may catch a train! The correct setting of the polarization filter unwanted reflections from the windows. In particular, the proper removal car paint color blue tones games.
Metal surface reflections are not polarized, so the filters do not enhance the image. In terms of metal objects - mostly glass and water - which is the Brewster angle - how to remove the optimum amount -with polarized light, so that the ratio will be lower, at 90 degrees and the polarization of polarized light is of no use. And in this case the light reflected from the leaves of trees or grass, is polarized, so you can improve your image.
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