Polarizing Filters

The polarizing filter is probably the single most used filter in a landscape/nature photographer’s bag because of its ability to cut glare and increase color saturation.  I find that I have the filter on my lens more often than not when I’m out in the field.

Polarizers are best used with normal to telephoto focal length lenses.  Regarding using a polarizer with wide angle lenses, I would recommend that you use caution because you may get uneven effects across your frame.  This uneven effect is especially noticeable if you have a lot of clear blue sky in the frame, and how noticeable the unevenness is depends on how much polarization you’ve dialed in.  Do some experimenting to see what you can get away with.  A polarizer relies on what’s called Brewster’s Angle as described in Brewster’s Law, discovered by a Scottish physicist named Sir David Brewster. For photographers, Brewster’s work gives us a simple tool to predict how a polarizing filter will affect the scene.  Using your thumb and forefinger, point your forefinger at the sun and point your thumb straight up.  As you rotate your wrist, keep your forefinger pointed at the sun, and everywhere your thumb points is where the polarization will be most pronounced.  Look through the viewfinder of your DSLR or use Live View to see the image on your camera’s LCD to adjust the filter for the effect you want.

Mid-day normally isn’t the best time to use a polarizer, but as the angle of the sun gets lower on the horizon, it can make a huge difference.  Overcast days are actually ideal for polarizers because they cut the reflections that rob the scene of color saturation.  Anytime you’re photographing water a polarizer can make a HUGE difference by cutting glare.  As you rotate the polarizer, you’ll see the surface glare disappear and you can see what’s under the water.  This effect is very useful when there is something just beneath the surface that you want to show.

In addition to cutting glare and increasing color saturation, polarizers also cut the amount of light reaching your sensor by 1 ½ to 2 stops so they’re useful for reducing exposure in high-contrast conditions as well.  The polarizer can also be stacked with a neutral density (ND) filter for ever greater light reduction with the added benefit of polarization.

The two images below show the effect of the polarizer on images of the “Devil’s Bathtub” in Hocking Hills State Park.  The first image has no polarization and the second does.  Notice how once the glare on the water is reduced, you can see the rocks underneath the surface of the water and how saturated the colors are.

 

The Devil’s Bathtub no polarization – Click image to enlarge

 

The Devil’s Bathtub with Polarization – Click image to enlarge

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