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Thread: What's a polariser?

  1. #1
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    Default What's a polariser?

    is it to take pictures on a really sunny day? it blocks reflections right? how does it to dat exactly? how is it different from a ND filter? how do i choose one? thanks!!

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    thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

    the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

    any polariser to recommend?

  4. #4

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    Originally posted by shuy
    thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

    the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

    any polariser to recommend?
    as u said, those are guidelines.

    polariser? you need to consult your camera's manual to see if you need either a linear polariser or circular polariser.

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    well, my manual doesnt say, but the article link says to use a circular one if i have an AF camera, which i do... how much is a decent one roughly?

  6. #6

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    depends on filter size

  7. #7

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    Originally posted by shuy
    thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

    the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

    any polariser to recommend?
    When light gets reflected from a surface (eg water surfaces or glass), it beomes polarize in that plane it is refleced from. the polarizer have strands of molecules that is aligned in a particular direction. when light past through the polarizer, the molecules oscillate and absorb most of the energy of the light in the same plane as the molecules. Hence only light polarize in that plane gets absorb. The rest past straight thru. (actually, everything is affected but light polarize in that axis is affected the most)

    HOwever, the reflection from shiny objects will not be greatly affected by the polarizer as the reflected light is not polarize in a particular plane. Hence, polarizer will not work in this case...

  8. #8
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    wah so cheem.... overdose of physics haha. thanks!

    my adaptor fits 49mm... how much would that be roughly?

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    actually polariser also can use as ND cos it cut off 2 stop of light too....

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    actually i want to get a polariser cos some of my pics look bland in the sunlight, i read that ND filters can be compensated by adjusting exposure, so i left that out. it seems a polariser can bring out the colour n contrast in sunny conditions...

  11. #11
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    Originally posted by shuy
    actually i want to get a polariser cos some of my pics look bland in the sunlight, i read that ND filters can be compensated by adjusting exposure, so i left that out. it seems a polariser can bring out the colour n contrast in sunny conditions...
    yup, solarise will help, but if without polarise, can try under 1/2 to 1 stop on sunny conditions, it also help...

  12. #12

    Default linear polariser

    Hi there,

    may i know what's actually the diff between linear and circular polariser?

    If i am currently using a AF digi cam and i use linear polariser,what will the effects be?

    I just bought one A series colkin linear polariser from CP,and the sales guy knows i am using the canon S30,but he did not mention that it will be better to use circular.

    Can anybody help me on this?

    Should i go and get another circular polariser?

    Thanks!

  13. #13
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    Default sorry

    Hi,

    the earlier post by SL6 is actually me.

    hmm.....dont know how come become SL6,though i logged in as eagles_creek.

    Hey SL6,you stay in woodlands?Maybe you forget to log-out?

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    u can read the link at the start of this thread, it said that circular polariser is better for AF cams... dunno the technical difference though.

    i have an e-quote of $31 for the Hoya circular filter 49mm, is that gd? the B+W and Cokin ones out of stock btw...

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    Linear polarisers DUN work for AF cameras. At least most of the time. This is because the AF system of your camera works by reading linear contrasts in the image. If you use a linear polariser, at certain angles, it will cut out the light from lines that the camera will need to read in order to get an AF reading.

  16. #16

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    not really.... depends on where the AF receptor is located. if the receptor is not TTL, then linear polariser should work.

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    i have an e-quote of $31 for the Hoya circular filter 49mm, is that gd?

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    Originally posted by mervlam
    not really.... depends on where the AF receptor is located. if the receptor is not TTL, then linear polariser should work.
    Having an AF receptor which is not TTL is very impractical lah. Imagine your hands or something else blocking it while you are trying to take a picture. How many cameras can you name that the AF receptor is not TTl?

  19. #19

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    I can name one: my good old Canon Prima 85N

  20. #20
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    Hello. You try fixing a polariser to that camera lah. Out-of-point siah. Must be you studying too hard oredi.....

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