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Thread: Need help on how to rotate circular polarizer

  1. #1

    Default Need help on how to rotate circular polarizer

    I know there are some threads on CPL already but I couldn't find the answer that I need.

    So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

    Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.

  2. #2
    Moderator daredevil123's Avatar
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    Default Re: Need help on how to rotate circular polarizer

    Quote Originally Posted by sci80899 View Post
    I know there are some threads on CPL already but I couldn't find the answer that I need.

    So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

    Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
    Simple. Just rotate till the pointer faces the sun.

    But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).

  3. #3

    Default Re: Need help on how to rotate circular polarizer

    Quote Originally Posted by daredevil123 View Post
    Simple. Just rotate till the pointer faces the sun.

    But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).
    very true, can't find any better technical way to answer ts question, other than rotate you like what you see in your VF
    Nikon D700, N24-70 f2.8, N70-200 f2.8, Sigma 50mm f1.4.

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    Senior Member zac08's Avatar
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    Default Re: Need help on how to rotate circular polarizer

    Quote Originally Posted by sci80899 View Post
    I know there are some threads on CPL already but I couldn't find the answer that I need.

    So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

    Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
    There is NO technical answers as it all depend on the angle of your view vs the angle of the light.
    Michael Lim
    My Flickr Site

  5. #5

    Default Re: Need help on how to rotate circular polarizer

    Quote Originally Posted by daredevil123 View Post
    Simple. Just rotate till the pointer faces the sun.

    But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).
    Thanks daredevil123, have a happy lunar new year.

  6. #6
    Moderator Octarine's Avatar
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    Default Re: Need help on how to rotate circular polarizer

    Quote Originally Posted by sci80899 View Post
    Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
    For the technical answer first you would need to know the orientation of the light rays that you want to keep. This can change, depending on whether you want to enhance a blue sky or remove reflections on a window. Keep it simple, use the method that you got from your reading
    EOS

  7. #7

    Default Re: Need help on how to rotate circular polarizer

    No offense to anyone ...

    For polarization to take place, both the light rays and polarizing film have to be at certain angles.

    However, it might be much easier to simply look through the viewfinder and rotate the pol filter till you get the effect you need. If you do want to be more technical, a photographic polarizing filter works best in the 30 - 56 degree range.

    For more details, Google 'how a polarizer filter works' but be prepared for a lot of physics and maths.
    Last edited by Dream Merchant; 13th February 2010 at 02:03 PM.

  8. #8

    Default Re: Need help on how to rotate circular polarizer

    Thanks guys. Happy CNY.

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