Polariser issue - a white balance issue?

Discussion in 'Beginner Questions' started by fred_monsone, Apr 18, 2011.

  1. Hi everyone,
    I just got an urgent email from a friend travelling around Vietnam. She's only just bought her first Canon DSLR and her first circular polariser. She emailed 'All photos using polariser filter are coming out blue. What am I doing wrong?'
    I have suggested changing the white balance to shade/cloudy/fluorescent but can anyone think of other reasons why her images are coming out blue? Thanks in advance for any suggestions.
     
  2. Hi Federica
    It is very difficult to say what the problem is without seeing a sample photograph or understanding the subjects and light conditions where your friend is taking her pictures, or what her camera settings are.
    Circular polarizers may have some impact on white balance but the changes are typically very subtle and hardly noticeable in general.
    I would ask her to check again the filter make and type. Then check whether taking pictures with the filter on and with the filter off makes any difference, and check whether the white balance settings are appropriate for the scene.
     
  3. Blue fringing is a sign of underexposure in digital cameras. She needs to use a "filter factor," and increase her exposures by a stop. One way to do this is to set the camera for +1 EV. Try that.
     
  4. if it is a cheap polarizer it could have that problem, but more likely she has accidentally changed the WB to tungsten ( the lightbulb icon) , ask her to set her camera to either AWB, flash, or sunlight WB and see if that makes a difference. Also to shoot raw, where WB can be reset when processing the raw images.
     
  5. +1 Daniel D: you need to post an example.
    A polarizer should have very little effect on overall color balance, but it can make skies look substantially more blue.
    Because the camera is metering through the lens (hence through the filter), I have never had to make the exposure adjustment John suggests, but if the picture is underexposed, you could try it.
    Most likely, it is an incorrect setting of white balance, but it would be hard to say without seeing one or two images.
     
  6. If your camera was set to Automatic White Balance, the camera will try adjust the colors for you, basically will "fight" the colors for you, and would not know that you have a polarizer or how it is set. Results will be random or unpredictable.
    You decide what white balance you want to use, that matches your lighting, and do not let the camera to interfere with it by doing any color guessing and adjusting. Generally AWB is not good for polarizers, mostly depends on the camera brand and model.
     
  7. Most polarizer filters are neutral density in color. I have sometimes used some of the cheapest PL filters I could find to fit on a lens and have never run into blueish casts even if the camera was set to AWB. I'm thinking it probably is something else, like the wrong WB setting.
     
  8. I would suggest you advise your friend to take off the PF, at least till the color issue is resolved.
    On a digital SLR, improper colors in the image is usually the result of the camera's White Balance setting not matching the actual light falling on the scene. For example, if you shoot an indoor pic with Flash, but have the camera White Balance set to Tungsten, then the image colors will be incorrect.
    The quickest way to approximate a quick fix is to set the White Balance to Automatic and just let the camera figure it out. That's easy to do, but the photographer wont be improving their skills that way.
    A more careful way is to carefully and continually observe The LIGHT that is actually falling on a scene & subject as you move around and take pictures. Then, practice the discipline of keeping the camera White Balance setting set on the WB mode tha best matches the light in the scene.
    For example, if your friend is outside on a bright sunny day, taking a pic of a landscape, then the Camera WB should be switched to Sunny mode. Then take the shot. But if clouds come over the sky, creating an overcast condition, then switch the camera WB to Cloudy. If she moves into a shady market, and takes pics of people & things in the shade, then switch the camera White Balance to the Shade mode. Or if she moves inside, and starts using the pop-up flash, then switch the camera White Balance to Flash mode. If she's under Florescent Tube lighting and decides not to use the Flash, then switch the white balance to Florescent. But if the ambient lighting is from filament type incandescent bulbs, then switch the WB to Tungsten mode. So, you see, the idea is to pay attention to what's going on with The Light on the scene, evaluate what type of light it is, and then try and set the WB accordingly.
    Sometimes a scene will have a mixture of several different kinds of light. For example, an indoor room might have daylight coming in from windows or skylights, florescent light comiing down from overhead tubes, and tungsten light coming from table lamps. In a case like this you can either try and guess which lighting is the most dominant, and set the WB to match that one. Or you can switch over to Automatic and pass the choice over to the camera.
    You can also try doing 'white balance bracketing'. That simply means shooting 3-4 pics of the same scene, but just switch to a different WB mode for each shot. This will result in a set of pictures that you can then look through and choose the one you like best.
    I think a UV filter is more often recemmended as a general protective filter on a lens.
     
  9. Unless she knows to rotate the PL to get the effect she wants, bluer skies, cut reflections off water, etc. it is pointless her having it on the camera. It is cutting 1.5 stops of light. A UV is better if she doesn't know how to protect her lens. Hope she has a lens hood and a case which will hold camera and hood permanently set up and ready to use. I agree she should use AWB until she knows more about photography.
     

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