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Thread: Rotation of CPL

  1. #1
    Member nivlaOof's Avatar
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    Default Rotation of CPL

    Hi guys..
    hope some of u can help me out.. i juz got a cokin CPL and was wondering does rotating the CPL make any diff? i tried it out but cant see any diff... so if you guys do rotate your cpl, wat are u rotating it for? wat are u trying to achieve?? .. pls advise

  2. #2
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    Default Re: Rotation of CPL

    U can 1st try by rotating it in front of yr LCD screen to see if it works. It will black out at some point, turn another 90deg, it will be at brightest.

    u can also try the same method on some reflactive surface like those glossy magazine. The reflection will be surpress.

    U can also try it on the sky with clouds, at some point u will see that the sky is bluer and the clouds are more contrasty.

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  3. #3

    Default Re: Rotation of CPL

    sorry...but wat is clp??haha

  4. #4
    Senior Member Galdor's Avatar
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    Default Re: Rotation of CPL

    Quote Originally Posted by ozkid88 View Post
    sorry...but wat is clp??haha
    You mean CPL? CPL = Circular Polariser. It's a kind of filter to block out the reflections in your subject. Try to google it.
    Minolta. Konica Minolta. Sony

  5. #5

    Default Re: Rotation of CPL

    Quote Originally Posted by nivlaOof View Post
    Hi guys..
    hope some of u can help me out.. i juz got a cokin CPL and was wondering does rotating the CPL make any diff? i tried it out but cant see any diff... so if you guys do rotate your cpl, wat are u rotating it for? wat are u trying to achieve?? .. pls advise
    Try rotating it 90 to the direction of the sun.

    Quote Originally Posted by ozkid88 View Post
    sorry...but wat is clp??haha
    CPL = Circular Polarizer

  6. #6
    Member nivlaOof's Avatar
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    Default Re: Rotation of CPL

    haha
    thanks guys...
    i tried infornt of my LCD.. saw the effect...i think i know wat its abt .. thanks

  7. #7

    Default Re: Rotation of CPL

    Quote Originally Posted by Galdor View Post
    You mean CPL? CPL = Circular Polariser. It's a kind of filter to block out the reflections in your subject. Try to google it.
    To be precise, it filters off polarised light. At certain angles, light reflected off surfaces like glass, water, leaves, etc, light will be polarised. This polarised light can be filter off by using CPL filters. Note that not all reflections can be filtered by CPL filters.

    BC

  8. #8
    Moderator catchlights's Avatar
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    Default Re: Rotation of CPL

    Quote Originally Posted by Scaglietti View Post
    To be precise, it filters off polarised light. At certain angles, light reflected off surfaces like glass, water, leaves, etc, light will be polarised. This polarised light can be filter off by using CPL filters. Note that not all reflections can be filtered by CPL filters.

    BC
    yeah, reflections from metallic surface can't be filtered....
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  9. #9
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    Default Re: Rotation of CPL

    http://dpfwiw.com/polarizer.htm

    Pretty heavy reading ... but very detailed

  10. #10

    Default Re: Rotation of CPL

    3 main things the CPL can be used for:

    1) Increase contrast in the sky, the further away the skies are from the direction of the sun, the more pronounced the effect. Note the divisions between the blue and the clouds. When no clouds will deepen the blues, but not very obvious if you ask me.

    2) Reduce reflections from NON-METALLIC SURFACES. Put your CPL on, find some water, look at the reflections and turn. They will reduce/disappear, and you can see beyond the depths of the water.

    3) 1-3 stop ND filter, depending on how you turn it.

  11. #11

    Default Re: Rotation of CPL

    Quote Originally Posted by night86mare View Post
    ...

    2) Reduce reflections from NON-METALLIC SURFACES. Put your CPL on, find some water, look at the reflections and turn. They will reduce/disappear, and you can see beyond the depths of the water.

    ...
    To add on...the effectiveness of this also depends on the angle you are shooting at the water or glass surface.

    BC

  12. #12

    Default Re: Rotation of CPL

    Quote Originally Posted by catchlights View Post
    yeah, reflections from metallic surface can't be filtered....
    Actually, to some extent, can. Not 100%, but up to 50% in some conditions (artificial light).

  13. #13
    Moderator LOTUSfairy's Avatar
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    Unhappy Re: Rotation of CPL

    I used a Hoya Circular Polarizer..dunno how to use...turn here turn there.. then kana too blue like this..


  14. #14

    Default Re: Rotation of CPL

    WOW! I just tried it with my kenko CPL and was shock to see pure black when i turn it to certain extent! thanks for the tip! hahaha.

    Quote Originally Posted by photougenics View Post
    U can 1st try by rotating it in front of yr LCD screen to see if it works. It will black out at some point, turn another 90deg, it will be at brightest.

    u can also try the same method on some reflactive surface like those glossy magazine. The reflection will be surpress.

    U can also try it on the sky with clouds, at some point u will see that the sky is bluer and the clouds are more contrasty.

    Hav Fun!!

  15. #15

    Default Re: Rotation of CPL

    Basic physics taught in secondary school...

    Light travels in straight lines in many planes due to its wave magnetic dual properties.

    PL allow light in only one plane to pass through, hence the name polarised.

    Reflections off non metallic surfaces all give polarised light, hence they can be cut off by the PL rotated off that exact plane.

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