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Thread: Do you know how REALLY a Circular Polariser works?

  1. #1

    Default Do you know how REALLY a Circular Polariser works?

    How many of you know how really a Circular Polariser works?
    And the difference between a Linear Polariser and Circular Polariser? And the applications?

    I would just like to know the understanding level of users of such filters in ClubSNAP.

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    Default Re: Do you know how REALLY a Circular Polariser works?

    Originally posted by mervlam
    How many of you know how really a Circular Polariser works?
    And the difference between a Linear Polariser and Circular Polariser? And the applications?

    I would just like to know the understanding level of users of such filters in ClubSNAP.
    Down to fundamental theory level in physics.
    Last edited by Ian; 21st January 2003 at 07:16 PM.
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    We discussed this a long time ago. Maybe a search may dig out that thread.

    Basically the first layer polarizes like a normal polarizer, and a second layer creats the circular polarization, which then looks like unpolaized light to polarization-sensitive optical equipment.
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

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    Originally posted by roygoh
    We discussed this a long time ago. Maybe a search may dig out that thread.

    Basically the first layer polarizes like a normal polarizer, and a second layer creats the circular polarization, which then looks like unpolaized light to polarization-sensitive optical equipment.
    the circular layer scatters the light is it? cool

    I never really bothered... it's not as if I am dangling 10 feet above a piranha pond and the rope is being cut by a slow laser and I have a foot holding a polariser...
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

  6. #6

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    Actually, which are the cameras that require unpolarized light for their AF to work? Some people may be buying Circular polarizors unecessarily. Btw, how much cheaper are linear polarizors? Do retailers even bother to stock them nowadays?

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    Originally posted by Zerstorer
    Actually, which are the cameras that require unpolarized light for their AF to work? Some people may be buying Circular polarizors unecessarily. Btw, how much cheaper are linear polarizors? Do retailers even bother to stock them nowadays?
    is it AF or metering? thought was latter...
    anyway think easier to just buy CPL than to find out if your cam needs it... current mentality.. cos dun think there's a drastic diff in price...
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

  8. #8

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    Originally posted by denizenx


    is it AF or metering? thought was latter...
    anyway think easier to just buy CPL than to find out if your cam needs it... current mentality.. cos dun think there's a drastic diff in price...
    Supposedly it can be either or both depending on the individual camera. Then again, agree on the part about just getting a CirPol for maximal compatibility and peace of mind.

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    Originally posted by Zerstorer


    Supposedly it can be either or both depending on the individual camera. Then again, agree on the part about just getting a CirPol for maximal compatibility and peace of mind.
    not to mention *circular* sounds more cool... like *extra* like that...
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

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    since u all r chatting about filters hope u dont mind i ask some questions . hehe thx.

    will having a CPL or a skylight helps in this case?
    when i take daylight or daytime shots my pics always comes out in like greenish tone

    seen here
    http://www.pbase.com/image/11273698
    http://www.pbase.com/image/11273671

    i try to adjust my whilte balane or EV
    still dont helps much

    http://www.pbase.com/image/11068781
    before edit in PS


    http://www.pbase.com/image/11101354
    after edti in PS
    will having a filter helps tp filters out the greennish tone i wont want to go to PS and tone out the greenish seen above lor

    ehe thx


  11. #11

    Default Re: Do you know how REALLY a Circular Polariser works?

    Originally posted by mervlam
    How many of you know how really a Circular Polariser works?
    And the difference between a Linear Polariser and Circular Polariser? And the applications?

    I would just like to know the understanding level of users of such filters in ClubSNAP.
    newbie here.......have read up before......forgot the theory behind......but roughly know when to use......what the difference it will make.....i think this is more impt than remember the theory rite?
    DSLR newbie: 400D + Tamron 18-200mm + 50mm F1.8 (i simply love it!)
    Canon G2

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    Default Re: Re: Do you know how REALLY a Circular Polariser works?

    Originally posted by digi~ET


    newbie here.......have read up before......forgot the theory behind......but roughly know when to use......what the difference it will make.....i think this is more impt than remember the theory rite?
    tone down the blue sky, kill reflections from one angle, slow down shutter.
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

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    Originally posted by denizenx


    the circular layer scatters the light is it? cool

    I never really bothered... it's not as if I am dangling 10 feet above a piranha pond and the rope is being cut by a slow laser and I have a foot holding a polariser...
    The second layer is essentially a quarter wave retarder. My understanding is that it takes half the polaized light and delays it by a quarter wavelength as well as rotates the polarization by 90 degrees.

    At any point after the second layer, the E-field then has a sine component in one direction and a cosine component perpendicular to it. The resultant E-field becomes a vector that rotates around the axis of propagation. Thus the name "Circular" polarizer.

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

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    Originally posted by roygoh


    The second layer is essentially a quarter wave retarder. My understanding is that it takes half the polaized light and delays it by a quarter wavelength as well as rotates the polarization by 90 degrees.

    At any point after the second layer, the E-field then has a sine component in one direction and a cosine component perpendicular to it. The resultant E-field becomes a vector that rotates around the axis of propagation. Thus the name "Circular" polarizer.

    - Roy
    argh! english!
    Last edited by denizenx; 22nd January 2003 at 02:48 AM.
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

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    Originally posted by denizenx


    argh! english!
    Well my first post was english enough, right?
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

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    Originally posted by pker88
    since u all r chatting about filters hope u dont mind i ask some questions . hehe thx.

    will having a CPL or a skylight helps in this case?
    when i take daylight or daytime shots my pics always comes out in like greenish tone

    seen here
    http://www.pbase.com/image/11273698
    http://www.pbase.com/image/11273671

    i try to adjust my whilte balane or EV
    still dont helps much

    http://www.pbase.com/image/11068781
    before edit in PS


    http://www.pbase.com/image/11101354
    after edti in PS
    will having a filter helps tp filters out the greennish tone i wont want to go to PS and tone out the greenish seen above lor

    ehe thx

    maybe a skylight filter will help? not sure, erm... it can be fixed in PS then no need to spend extra money i feel.

    btw, u work in amoy?

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    u asking me?
    err actiually lastime i working in temasek towers
    like the food there cheap and good but too bad now all closed
    for reno


    and now is full time slacker

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    Default

    Originally posted by denizenx


    is it AF or metering? thought was latter...
    anyway think easier to just buy CPL than to find out if your cam needs it... current mentality.. cos dun think there's a drastic diff in price...
    There is a difference in price.... Linear's about half the price of circular I think.

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