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Thread: Vignetting using CPL on wide angle

  1. #1
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    Default Vignetting using CPL on wide angle

    Hi all,

    I just got a polarising filter (Hoya Pro 1) for my new Canon EOS 500D. (Actually, I had intended to buy a filter for protection i.e. UV filter, but obviously didn't do enough homework. ) Anyway, I was playing around with it and taking some snow pics. Cos' I read it's also good for cutting out reflection from snow?

    When I came back and viewed the pics, I realized the corners in some of them are dark. Then, I didn't know much about vignetting, so I read up and realized it seems to occur when using a CPL on wide angle shots? To that, I have some questions that hopefully dear all can help to clarify.

    I assumed most people would use a CPL for landscape shots since it's supposed to increase colour saturation of skies, water etc. And most landscape shots would be taken in wide angle or using wide angle lens, right? So, if CPL causes vignetting in wide angle shots, why do people still use it? Is there any way to rectify the problem? I hope I'm making sense here. Please correct me if I'm wrong.

    On top of the vignetting in my wide angle shot (Pic 1 below), it also seems to occur in a zoomed-in photo (Pic 2). Why is that so? But I realised in a wider-angle view of Pic 2, there's no vignetting (Pic 3). Why why?

    I have more questions pertaining to snow white balance and referring to the same photos. But I guess it's more appropriate to post it as a new thread under a different heading.

    Please feel free to comment on the photos, criticize, tear it apart, anything.

    Thanks!

    Btw, all photos were taken with EF-S 18-135mm 3.5-5.6 lens.


    Focal length=18mm, f/8


    Focal length=92mm, f/8


    Focal length=50mm, f/8
    Last edited by sharenmun; 3rd February 2010 at 12:04 AM.

  2. #2

    Default Re: Vignetting using CPL on wide angle

    the vignetting may not be caused by the CPL, were you shooting wide open (i.e. widest aperture)? for this lens, there will be some obvious vignetting at 18mm and 135mm, and become less obvious for focal length in between.

    quote from the this site:
    Expect to see some vignetting in the corners at the ends of the focal length range - About 2.5 stops of shading in the 18mm corners and 2 stops in 135mm corners. The amount of corner darkening becomes just-noticeable in the middle range of focal lengths and, as always, stopping down the aperture 1 stop makes a noticeable improvement in this regard.

    what you can try:
    1. try shooting the same scene wide open with and without CPL.
    2. try stopping down 1 stop or more with and without CPL.

    HTH.

  3. #3

    Default Re: Vignetting using CPL on wide angle

    Imagine the lens is your window. At widest end, the lens utilize the whole window area but as you zoom, the area used narrowing to the centre. Which is why vignetting with thick rim flter is visible on the wide end.

    Some wide angle lens overcome this problem by having a large thread ring with lens much smaller than the ring. This however has a disadvantage of high cost filter since diameter is larger.

  4. #4
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    Default Re: Vignetting using CPL on wide angle

    Miaoteh, thanks for the link. As I've just included, all three photos were taken at f/8, and not the widest aperture, which according to the review, would have then caused the problem. So, I'm still baffled.

    Spheredome, thanks for your window analogy, which made it easy for me to understand. But if so, why was there still vignetting even at 92mm (Pic 2)?

    Sigh, I should have also taken the same shots without the CPL for comparison.

  5. #5
    Senior Member denniskee's Avatar
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    Default Re: Vignetting using CPL on wide angle

    may i suggest u read these

    vignetting
    http://toothwalker.org/optics/vignetting.html

    using CP on wide angle lens
    http://www.cambridgeincolour.com/tut...0%27none%27%3B
    photography makes one sees things from all angles.

  6. #6

    Default Re: Vignetting using CPL on wide angle

    Quote Originally Posted by sharenmun View Post

    And most landscape shots would be taken in wide angle or using wide angle lens, right?
    wrong, maybe with the exception of some CS's photographers.

    all the landscape shot i like weren't taken with wide.
    the perspective is so totally wrong.

  7. #7

    Default Re: Vignetting using CPL on wide angle

    Quote Originally Posted by bengchiat View Post
    wrong, maybe with the exception of some CS's photographers.

    all the landscape shot i like weren't taken with wide.
    the perspective is so totally wrong.
    http://www.adamburtonphotography.com/

    http://www.davidclapp.co.uk/index.php

    http://www.marcadamus.com/

    anyways, no, you do not have to use wide angle for landscapes, but you can. almost every focal length can be useful in landscapes, to be honest.

  8. #8

    Default Re: Vignetting using CPL on wide angle

    As mentioned by miaoteh, your vignetting is more of the light fall towards to side. Vignetting caused by thick filters are very define black. Lens by nature will have lesser light falling on around the circumference but probably the CPL make this worse in low light. And because you scene is so uniform light colored, the fall off becomes very prominent. Lens vignetting is less prominent is bright and non uniform colored scene.
    Some Canon dSLR has optical illumination feature to self correct these problem but only apply to Canon lens.

    In landscape, I will always take into account of the unused corners and ready to crop off when used with CPL filter. And CPL is not to be used when light is inadequate.

    Quote Originally Posted by sharenmun View Post
    ...
    Spheredome, thanks for your window analogy, which made it easy for me to understand. But if so, why was there still vignetting even at 92mm (Pic 2)?

    Sigh, I should have also taken the same shots without the CPL for comparison.

  9. #9

    Smile Re: Vignetting using CPL on wide angle

    Do u used lens hood at that time ? it's also may cause vignetting .
    EOS 500D + EF-S 17-55mm f/2.8 IS USM + EF 50mm f/1.8 II

  10. #10

    Default Re: Vignetting using CPL on wide angle

    The sky is overcast, why would you still use CPL?

    Anyway even on a shiny blue sky, if you use CPL on UWA lens, you will see uneven blue sky where the corner has a darker blue.

    That is the reason i don't use CPL but prefer square GND filter if i use UWA lens

  11. #11
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    Default Re: Vignetting using CPL on wide angle

    1) I wouldn't use CPL on such a scene if i were you. haha there's not much diff with or without right?

    2) When shooting snow, it is advisable to increase exposure compensation by around 2/3 stop. because the metering tends to get fooled with such a scene.

    3) It is a common misconception that landscape photography always means wide angle. many photographers use lenses like 70-200 for landscape too.
    Photography is about seeing without a camera.
    60D | LX3 | Flickr

  12. #12

    Default Re: Vignetting using CPL on wide angle

    Try using slim filters or polarizers.
    Avoid stacking the PL on the UV filter.

    http://photonotes.org/cgi-bin/photo-...?id=Slimfilter

  13. #13
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    Default Re: Vignetting using CPL on wide angle

    Wow! Thanks everyone for your comments and advice. I'm learning something new everyday!

    Seems like my perception of landscape=wide angle is flawed. Actually I didn't read this anywhere. It's just my own assumption cos' most of the beautiful landscape pics seem to have a feeling of vastness, and so I just assumed it was taken with a wide angle lens.

    One thing I'm really curious, are those super beautiful landscape photos with super nice colours usually photoshopped? Cos' I can't imagine my lens taking in such beautiful colours.

    Oh, I wasn't using a hood when taking those photos. And I had just got the new filter then, and since I didn't really know how to use it, I was just playing around and seeing what effects it really add. And I'm glad I did, cos' it made me learn so many new things.

    So, now I gather I shouldn't use the CPL on low light scenes, uniform scenes, anything else?

    Spheredome, what do you mean by 'light fall towards to side'? Do you mean that the light source is shining from eg. my left/right?

    And yes, I did try to take another (uniform) scene at the biggest aperture with and without the filter. True enough, even without filter, there was vignetting at the extreme focal lengths. Pls tell me this is normal for all zoom lens? Or is it just my 18-135mm, which I've already heard not-so-great reviews about.

    Once again, thanks to all 'Sifu'!

  14. #14
    Senior Member ZerocoolAstra's Avatar
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    Default Re: Vignetting using CPL on wide angle

    Your photos look rather dull because they are essentially underexposed. The white snow fools the camera's exposure meter. You should have used exposure compensation of at least 2/3 stops.

    The fall-off at the corners seems rather strange, especially at 92mm f/8.
    Did you stack your CPL on top of your UV filter?
    Exploring! :)

  15. #15

    Default Re: Vignetting using CPL on wide angle

    I cannot explain the deep reason but a quick understanding is that maximum light (assuming wide source light) passed thru the central area of the lens and the amount entering thru the lens reduces towards the outer circumference. Thus in a uniform lighted surface, it becomes noticeable. In most situation, light is uneven because of the uni source like sun or shadow or reflected surface.

    Same goes for optic quality where the sharpest part tends to be the centre. Thus wide lens tends to result with softer wide, similar to your eyes (sharp front blur side).

    Quote Originally Posted by sharenmun View Post
    ...

    Spheredome, what do you mean by 'light fall towards to side'? Do you mean that the light source is shining from eg. my left/right?

    And yes, I did try to take another (uniform) scene at the biggest aperture with and without the filter. True enough, even without filter, there was vignetting at the extreme focal lengths. Pls tell me this is normal for all zoom lens? Or is it just my 18-135mm, which I've already heard not-so-great reviews about.

    Once again, thanks to all 'Sifu'!

  16. #16
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    Default Re: Vignetting using CPL on wide angle

    Quote Originally Posted by spheredome View Post
    I cannot explain the deep reason but a quick understanding is that maximum light (assuming wide source light) passed thru the central area of the lens and the amount entering thru the lens reduces towards the outer circumference. Thus in a uniform lighted surface, it becomes noticeable. In most situation, light is uneven because of the uni source like sun or shadow or reflected surface.

    Same goes for optic quality where the sharpest part tends to be the centre. Thus wide lens tends to result with softer wide, similar to your eyes (sharp front blur side).
    Cheem... Had to read few times to understand. The eye one was easy, though.

    Quote Originally Posted by ZerocoolAstra View Post
    Your photos look rather dull because they are essentially underexposed. The white snow fools the camera's exposure meter. You should have used exposure compensation of at least 2/3 stops.

    The fall-off at the corners seems rather strange, especially at 92mm f/8.
    Did you stack your CPL on top of your UV filter?
    Yes, it is strange. Nope, I was only using the CPL then.

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