A&P EDU: Understanding what circular polarizers do for photos.

Discussion in 'Lifestyle' started by FindersKeepers, Jul 14, 2008.

  1. FindersKeepers

    FindersKeepers New Member

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    In this EDU I'll try with the best of my knowledge and limited photos to show you the effects of circular polarizers for your photos... In these examples I'll be showing you Automotive use, and Water use...

    Circular Polarizers, also known as CPL's allow only certain light rays to pass through it. Depending on the orientation of the filter, it can reduce glare, make greens and blues more saturdated against each other, reduce reflections on water and automobiles, and also can be used as a neutral density filter.

    CPL's generally have two rings, the threaded ring that threads into your UV"lens protector" filter, or straight onto the lens if you have no UV filter...
    The second ring allows you to adjust the effect the CPL has, on most Point and shoot cameras you can see this effect via the LCD screen, and on SLR/DSLR you can see it via the viewfinder.

    note: The CPL should always be the very LAST filter you place on your lens, with the exception of the lens cap (meaning Lens -> UV -> CPL - > CAP ).


    note 2: When shooting in semi auto or automatic modes (P, TV, AUTO) your exposure will be decreased by a few stops of the aperture, in AV mode your shutter speed will be decreased with a CPL on in low light conditions, in very bright conditions it still may stop it down a bit, but usually not as much. I have posted, above the photos, shooting information.


    I took the car and mirror photos on Manual, 50mm F/2.0 1/200 at iso 100

    The pool was done on P mode - filtered - f/4.0 1/200sec iso100, and unfilterd f/4.5, 1/250 at iso 100


    here are some side by side examples of what a CPL will do...

    With a Car - Reflections greatly reduced, glare greatly reduced, while not 100% gone is a a lot better than normal, you get more paint color than sky.

    This is especially useful when photographing vehicles in all conditions to reduce background glare, and if you are trying to capture the driver you'll be able to better do so by reducing the glare on the windows... (Paparazzo use this to capture celebs in their cars during daylight hours as it allows a direct through view in most cases)

    [​IMG]

    again with a vehicle description.. This is a side view mirror on a GMC Pickup, it's picking up the reflection off of the vehicles window, which is of my neighbors chimney and antenna.. With the CPL on, all it shows is the deep black of my tint.

    [​IMG]

    And in this one, a pool... With filter you can see into the water and the floor of the poool better than without the filter... this can be useful when photographing people in the water, fish, animals, etc.

    [​IMG]


    A CPL can also saturate sky/trees a lot...

    Example WITHOUT CPL:
    [​IMG]

    EXAMPLE WITH CPL
    [​IMG]



    when taking these I turned the CPL to its MAX effect for the greatest difference from filtered to unfiltered


    Any questions/corrections? :o
     
  2. Bloke

    Bloke Banned

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    whats the diffrence between linear and circular
     
  3. f/2.8L

    f/2.8L New Member

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    Lines & Circles? :dunno:





    :mamoru:
     
  4. mojito

    mojito New Member

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    linear = no AF
     
  5. isaac86hatch

    isaac86hatch This thread sucks

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    Nice little edu. Though you should mention that capturing the full effects of a CPL is completely dependent on the angle you create between you, the subject and the sun.
     
  6. Curren$y

    Curren$y New Member

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    why do a lot of pros not use filters?
     
  7. Bloke

    Bloke Banned

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    besides that?
     
  8. mojito

    mojito New Member

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    UV = lose
    most other filters are pretty genre specific or got left in the dust with film
    that was the whole point. they're made differently to allow AF
     
  9. FindersKeepers

    FindersKeepers New Member

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    I only use a CPL when I'm shooting outdoors/automotive/boat&Watersports

    I only use UV as a front element protector, its cheap insurance to keep the front element from being scratched/damaged.. Better to break a cheap ass filter than n expensive lens.


    To explain the difference of linear/circular I grabbed this from WIKI

     
  10. Bloke

    Bloke Banned

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    so the EV value of a linear is the same as a circular? they have the exact same look?
     
  11. ¤

    ¤ New Member

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    thanks for the EDU :cool:
     
  12. FindersKeepers

    FindersKeepers New Member

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    Not totally in my experience.

    From what I've noticed visually (unmetered/etc) is that the CPL depending on where it's turned to, tends to have more of an EV effect then the linear

    But then again, linears weren't meant to be used on a film slr, or a digital slr.
     
  13. FusionZ06

    FusionZ06 /\__/\__/\__0>

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    Always cool - I just have a UV filter on my lens to protect the element :o
     
  14. Bloke

    Bloke Banned

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    skylight>uv :mamoru:
     
  15. FindersKeepers

    FindersKeepers New Member

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    Same

    I only use the CPL in some situations and not all, i hate the EV drop
     
  16. xenon supra

    xenon supra OT Supporter

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    my CPL actually should arrive today or tomorrow. I'll post samples :coold:
     
  17. Derrict

    Derrict No, I am not Amish OT Supporter

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    Yeah. If you're positioned at a 90 degree angle from the sun, you will get the full effect of a polarizer.

    Here's a shot at 90 degrees from the sun
    [​IMG]


    Shift to the right and I'm at about 130 degrees from the sun, so the sky isn't as dark of a blue
    [​IMG]
     
  18. xenon supra

    xenon supra OT Supporter

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    can someone explain how adjusting the ring affects the results? it doesn't seem to matter on mine it gives pretty much the same stuff. It has a blue notch that can be rotated around on the outer ring, where should it be for max effect and where should it be for min effect?

    :dunno:
     
  19. FindersKeepers

    FindersKeepers New Member

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    If im not mistaken, I dont believe there is any one way to answer that, my 52mm polarizer for the 50 lens and the 72mm for the 28-135 are definitely different in terms of where it happens and so on

    It also depends on yrou angle from the light source, such as the sun, etc.

    It'll depend solely on the filter itself, whether it was made correctly or not/etc.
     
  20. Tvan

    Tvan New Member

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    My 50mm f/1.8 is coming in the mail with a cpl tomorrow, I can't wait. :run:
     
  21. Derrict

    Derrict No, I am not Amish OT Supporter

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    Once you have it installed, you can visually see the difference in the viewfinder as you turn the CPL.
     

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