Need help with polariser


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enyu

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Dec 28, 2005
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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:embrass: :embrass:
http://gallery.clubsnap.com/showphoto.php/photo/62833/cat/500/size/big/ppuser/26183
 

kcuf2

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Dec 29, 2005
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#2
enyu said:
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:embrass: :embrass:
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.
 

enyu

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#4
thks KCUF2.... ;) yes im using a circular ppl, but why are there shadows around the 4 corners of the pic ??:cry: 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:) :)
 

enyu

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Dec 28, 2005
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#5
sorry.... not very familiar with uploading pic...thousand apologies :embrass: :embrass:
 

enyu

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#6
+evenstar... what is light loss in photography terms ??
 

ExplorerZ

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Jan 9, 2006
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#7
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
 

enyu

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Dec 28, 2005
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#9
what is a CPL ??:embrass: 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 ;p u mean playing with the zoom till i don't see the vignettes ??? HOW CAN I OVERCOME LIGHT LOSS ??
 

enyu

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Dec 28, 2005
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#10
Thks for advice ExplorerZ, this one taken using same ppl, but no vignette. plse advice any improvement or correction needed... tks tks:D :D
 

Francis247

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#11
enyu said:
what is a CPL ??:embrass: 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 ;p 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.
 

Friday13

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Aug 2, 2005
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#12
Francis247 said:
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! :thumbsup: Bro! I think you should be photographer by profession and engineer by passion!:thumbsup: :bsmilie:
 

Francis247

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#13
Friday13 said:
Pro advise! :thumbsup: Bro! I think you should be photographer by profession and engineer by passion!:thumbsup: :bsmilie:
:embrass:
Alamak, White Plo suan me leh. ;p

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???
 

espn

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Dec 20, 2002
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#14
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?
 

enyu

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Dec 28, 2005
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#16
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.. :thumbsup: :) need to get myself a good book for digital photography.;p
 

Artosoft

Senior Member
Aug 31, 2005
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#17
enyu said:
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.. :thumbsup: :) need to get myself a good book for digital photography.;p
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.
 

enyu

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Dec 28, 2005
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#18
thks ARTOSOFT.... will do that in future... cheer;)
 

Friday13

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Aug 2, 2005
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#19
Francis247 said:
:embrass:
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. :thumbsup:
 

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