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Thread: Need help with polariser

  1. #1

    Default Need help with polariser

    I bought a polariser recently, tried out today at Sentosa, but there are these black shadow at the 4 corners of the pic, only on some pic i took, just wondering am i using it the correct way, do i rotate it till i get the darkest image ? when do i actually need to use a polariser, on landscape only, can i use it for portrait ? indoor or out door ????? i am a beginer, hope my questions won't sound stupid to all. tks tks
    http://gallery.clubsnap.com/showphot...g/ppuser/26183
    Last edited by enyu; 10th June 2006 at 08:45 PM.

  2. #2
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    Default Re: Need help with polariser

    Quote Originally Posted by enyu
    I bought a polariser recently, tried out today at Sentosa, but there are these black shadow at the 4 corners of the pic, only on some pic i took, just wondering am i using it the correct way, do i rotate it till i get the darkest image ? when do i actually need to use a polariser, on landscape only, can i use it for portrait ? indoor or out door ????? i am a beginer, hope my questions won't sound stupid to all. tks tks
    i assume urs is a circular polariser, actually ppl normally use it to make the blue sky more blue, and the water more blue etc..make the image look nicer. and of course, it can be use in landscape, portrait and whatever there is.. there is no limit.

    another advantage of the polariser is when u are shooting behind a glass window, the polariser can help to reduce the glass reflection by a lot, thus the shot will appear as if u shot an object without a glass.
    09 Oct 09 officially marks the date I become a canon convert.

  3. #3
    Senior Member +evenstar's Avatar
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    Default Re: Need help with polariser

    must you post up 4 IDENTICAL links?

    yours is a case of vignetting or light loss i think...correct me if i'm wrong
    eat. drink. shoot

  4. #4

    Default Re: Need help with polariser

    thks KCUF2.... yes im using a circular ppl, but why are there shadows around the 4 corners of the pic ?? how do i know when to stop turning the ppl, when the sky turns more 'BLUE' ?? .. what about when taking other pic beside those with sky, when do i stop rotating the ppl... tks tks

  5. #5

    Default Re: Need help with polariser

    sorry.... not very familiar with uploading pic...thousand apologies

  6. #6

    Default Re: Need help with polariser

    +evenstar... what is light loss in photography terms ??

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    Default Re: Need help with polariser

    yes very obvious corner vigetting. all you can do is to take it off/use a slim CPL instead of normal one/zoom in ur lens alittle

    btw the photo link you posted looks very underexposed, and i can see obvious banding on the sky area

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    Default Re: Need help with polariser

    Quote Originally Posted by enyu
    +evenstar... what is light loss in photography terms ??
    light loss like what it name is or simply means lesser light entering the lens and reaching the sensor compare to the other part of the frame

  9. #9

    Default Re: Need help with polariser

    what is a CPL ?? I used exposure lock at the sky, i thought by doing this i won't get a sky that is too bright... sorry... still a begineer u mean playing with the zoom till i don't see the vignettes ??? HOW CAN I OVERCOME LIGHT LOSS ??
    Last edited by enyu; 10th June 2006 at 08:57 PM.

  10. #10

    Default Re: Need help with polariser

    Thks for advice ExplorerZ, this one taken using same ppl, but no vignette. plse advice any improvement or correction needed... tks tks [img]http://gallery.clubsnap.com/showphot...ze/big/cat/501[/img]
    Last edited by enyu; 10th June 2006 at 09:11 PM.

  11. #11
    Moderator Francis247's Avatar
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    Default Re: Need help with polariser

    Quote Originally Posted by enyu
    what is a CPL ?? I used exposure lock at the sky, i thought by doing this i won't get a sky that is too bright... sorry... still a begineer u mean playing with the zoom till i don't see the vignettes ??? HOW CAN I OVERCOME LIGHT LOSS ??
    Hi there,

    Guess there will be quite a few questions on your mind. Why don't we tackle it one at a time.

    1. CPL - Circular Polariser for short, sometimes also refer to as CIR-PL
    2. Light Loss - As indicated, it is a loss of light. Light is the most basic for photography. Photography is about light. To understand why using CPL will suffer light loss, you need to understand about exposure.
    3. To understand about exposure, you can follow this thread to find out more or maybe this article for the Clubsnap website.

    Hope that it can help. After you understand about exposure, the rest of the explanation here will be much easier.

    BTW, the 4 dark corners as in your photo is known as vignetting. The main cause of vignetting is due to stacking of filters. Most of the time, stacking of filter shouldn't be an issue unless the filters are quite thick (Normal CIR-PL are quite thick as it consists of 2 layers of filters) and may cause vignetting at wide angle especially. I believe that is why some of your shots have these 4 dark corners while some don't have because you change the focal length from maybe 18mm to 28mm (just an example).

    For my practise, either normal or IR shooting, if I need to use a CIR-PL or R72 when shooting, I will remove my UV filter if I am shooting at wide angle range of less than 24mm just to prevent vignetting due to filter stacking.
    Last edited by Francis247; 10th June 2006 at 10:12 PM.
    莫问前程有愧,只求今生无悔. Time pasts, Places changed, Beauty faded, what is left are Photos of Memories…

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    Default Re: Need help with polariser

    Quote Originally Posted by Francis247
    Hi there,

    Guess there will be quite a few questions on your mind. Why don't we tackle it one at a time.

    1. CPL - Circular Polariser for short, sometimes also refer to as CIR-PL
    2. Light Loss - As indicated, it is a loss of light. Light is the most basic for photography. Photography is about light. To understand why using CPL will suffer light loss, you need to understand about exposure.
    3. To understand about exposure, you can follow this thread to find out more or maybe this article for the Clubsnap website.

    Hope that it can help. After you understand about exposure, the rest of the explanation here will be much easier.

    BTW, the 4 dark corners as in your photo is known as vignetting. The main cause of vignetting is due to stacking of filters. Most of the time, stacking of filter shouldn't be an issue unless the filters are quite thick (Normal CIR-PL are quite thick as it consists of 2 layers of filters) and may cause vignetting at wide angle especially. I believe that is why some of your shots have these 4 dark corners while some don't have because you change the focal length from maybe 18mm to 28mm (just an example).

    For my practise, either normal or IR shooting, if I need to use a CIR-PL or R72 when shooting, I will remove my UV filter if I am shooting at wide angle range of less than 24mm just to prevent vignetting due to filter stacking.
    Pro advise! Bro! I think you should be photographer by profession and engineer by passion!

  13. #13
    Moderator Francis247's Avatar
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    Default Re: Need help with polariser

    Quote Originally Posted by Friday13
    Pro advise! Bro! I think you should be photographer by profession and engineer by passion!

    Alamak, White Plo suan me leh.

    Ok lah, let's us not OT in this thread. Hope to see you for the next fun outing. Told espn to get a "White" TC 1.7EII for you. Haha.

    BTW, just for discussion purposes, how is your Nikon CIR-PL, I believe should not and will not have vignetting issue, do you have any wide-angle comparison between Hoya and the Nikon CPL???
    莫问前程有愧,只求今生无悔. Time pasts, Places changed, Beauty faded, what is left are Photos of Memories…

  14. #14
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    Default Re: Need help with polariser

    Looks like vignetting to me, you probably stacked too many filters on top of each other. However, the vignetting looks pretty serious to me, what filters were you using on the glass?

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    Default Re: Need help with polariser

    Your pics seem under expose...

  16. #16

    Default Re: Need help with polariser

    thks everyone.... sorry for replying late, slept early last nite, yes i was using UV and CPL + wide angle shot, alot of basic digital photograpy to catch from all of you.. need to get myself a good book for digital photography.

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    Default Re: Need help with polariser

    Quote Originally Posted by enyu
    thks everyone.... sorry for replying late, slept early last nite, yes i was using UV and CPL + wide angle shot, alot of basic digital photograpy to catch from all of you.. need to get myself a good book for digital photography.
    Vignetting occurs since you are using UV + CPL + Wide angle shoot.

    To avoid vignetting:
    - Try to remove UV filter, and use only CPL filter.
    - Try to use lens' FL 35mm instead of 28mm. If you are using kit lens (zoom lens), you can 'tarik' a bit to 35mm (or until you can't see vignetting on preview LCD, that's one of DSLR's advantage).

    Regards,
    Arto.

  18. #18

    Default Re: Need help with polariser

    thks ARTOSOFT.... will do that in future... cheer

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    Default Re: Need help with polariser

    Quote Originally Posted by Francis247

    BTW, just for discussion purposes, how is your Nikon CIR-PL, I believe should not and will not have vignetting issue, do you have any wide-angle comparison between Hoya and the Nikon CPL???
    For wide angles which I usually shoot at 17mm for digital, Stacking the Nikon CPL II on top of UV does not produce vignetting for me. But for better results, I prefer to shoot with the CPL alone.

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