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Thread: Circula Polarizer

  1. #1
    Member Koh Li Kuan's Avatar
    Join Date
    May 2003
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    Bedok Reservoir
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    73

    Default Circula Polarizer

    Hi,

    I dropped my CP and the glass panel fell off. I fixed is back but not sure if the glass direction is correct(because 1 side blocks light while the other let in)

    I know while looking at a mirror thru 1 particular side of the CP will have effect of blocking light. Can some kind soul out there tell me while this happens, the male screw thread should be facing you or the mirror?

    Thanks a million....

  2. #2
    Senior Member
    Join Date
    Jan 2002
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    Northwest
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    5,011

    Default Re: Circula Polarizer

    Originally posted by Koh Li Kuan
    Hi,

    I dropped my CP and the glass panel fell off. I fixed is back but not sure if the glass direction is correct(because 1 side blocks light while the other let in)

    I know while looking at a mirror thru 1 particular side of the CP will have effect of blocking light. Can some kind soul out there tell me while this happens, the male screw thread should be facing you or the mirror?

    Thanks a million....
    I think 1 side polarizes like a linear polarizer while the other side contains a quater wave retarder that effectively de-polaizes the light that is polarized by the first side.

    To find out which is which, stack the glass with another polarizer, look through the stack and slowly rotate the polarizer. If the image turns dark at some angle and then brighter at others, then the side of the glass that is facing the other polarizer is the polarizing side, thus it should face the subject.

    If the image looking through the stack does not change in brightness when you rotate the polarizer, then the side facing the polarizer is the de-polarizing side and it should face the lens.

    - Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

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