Polarizers Revisited

This is a follow up on an earlier piece on polarizers.

Polarizers are typically used to

  • Darken the sky and thus pop the clouds and
  • Control reflections. Their ability to control reflections also can be used to
    • Increase color saturation when moisture in the air or on foliage would otherwise result in reduced color
    • This effect is most pronounced with rainbows. Use a polarizer and rainbows will really pop.

Let’s look specifically at reflections. A polarizer can control reflections caused by water and glass – but not metal. The control you can exert varies from allowing the full reflection to “shine on through” to reducing the reflection to almost zero – and all points in between. Certain conditions must be met. In simple terms just ask yourself – where is my shadow (or similarly where is the sun)? If the answer is –

  • To my side then the polarizer will preform to its maximum effect
  • In front of, or behind, me the the polarizer’s effect is minimum
  • At points in between – the effect is somewhere between minimum and maximum.
  • Be aware that if you’re using a wide angle lens the angle of the sun’s light will vary from one angle of view to another.
    • Suppose the sun is directly overhead – the sky overhead will be unaffected and the sky at the horizon will be affected to the maximum (if your focal point is on the horizon)
    • Suppose the sun is low and directly to your left or right – the sky straight ahead will be dark (maximum effect) and the sky at the left & right edges of the frame will be lighter (how light depends on the field of view of your lens – there will be almost no polarizer effect at the left and right edges if you’re using a very wide angle lens with the sun at right angles to your shot)
    • This graduated change in the sky’s color, when using a polarizer on a wide angle lens, can be appear unnatural and potentially ruin a shot – beware.
  • Best advice – hold the polarizer up to your eye (or look through the viewfinder) and rotate it. You’ll easily see what you’re going to get (or not get).

Here are two side by side examples (click to enlarge) which show the reflection extremes. I routinely have a circular polarizer attached to my lens.  As in all other matters dealing with making an image, I want to decide what reflections are present and not just take what the camera gives me.

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For an update on polarizers, read this post.