Polarizing Filters, Reflections and Saturation
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Photo by Steve Dunwell, DPA Instructor, Boston
Steve used a Polarizing Filter on his lens to capture the image above of an idyllic seaside shot. The Pola filter gives you more definition and drama in the sky, with the bright white clouds in contrast with a darker blue sky. You can also see evidence of the filter in the increased saturation of the foliage and water.
A Polarizing filter is a dark glass filter that attaches to the front of your camera lens. You buy a filter that fits the barrel size of your particular lens. A Pola filter looks dark like sunglasses and is usually neutral in color, although some Pola filters have a warm tone built into the glass. The basic elements are a threaded ring to attach to the lens attached to a static ring that rests against the lens once mounted. Then there is a rotating ring which spins freely (usually in either direction) like a rotating bezel. This ring holds the glass Polarizing filter. As this ring spins the polarizing effect takes place depending on the position of the glass in relation to the light source. You can mount a Polarizing filter on most DSLR cameras and even on some point and shoot cameras. The Polarizing filter is one of the few actual filters you need to purchase now that white balance adjustments are controlled electronically in camera by JPEG processing or in computer with RAW import.
When using Polarizing filters there are a few tricks to master. You need to get used to adjusting and spinning the filter every time you move the camera. Each time you alter the direction the lens is aimed, either by angle or camera position you effectively alter the effect of the Polarizing Filter and must adjust or compensate for this. Luckily you can actually see the effect in the viewfinder or on the LCD screen. A good indicator is to look at the blue sky in the scene, assuming there is a sky. The effects of polarization will be more evident and easier to spot in the blue sky and also in reflective surfaces, windows etc. With practice this like everything in photography becomes second nature.
The other issue is exposure. Because a Pola filter is dark, usually by 1-2 stops of exposure, the filter will affect your camera exposure as you spin it. Thus if you use your camera on manual mode your exposures will be all over the place, changing each time you spin the filter or change camera position. You’re better off using a semi-auto mode such as Aperture Priority when you use a Polarizing filter.
Photo by John Bentham, DPA Instructor, New York
This image was shot with a Polarizing filter eliminating the reflections on the water allowing the camera to capture an image showing detail depth into the water itself, much more interesting than just the surface of the water.
Even if you do everything right and utilize a Pola Filter there are times when an image needs a little fix. Maybe the Polarizing effect is a little too much, there is a fine line between a rich blue sky and a over-Polarized looking sky. This is where NIK Software can help, quickly and painlessly by applying carefully placed Control Points you can easily correct and remove incorrect color casts in select specific portions of a photograph. NIK works as a Plug-In for Photoshop, Aperture or Lightroom. I find it works much faster than Photoshop alone for this type of correction.
Alternatively if you didn’t have a Polarizing filter with you when you shot an image, or you were using a camera that can not accept eternal filters (like many point and shoot models) you can fake a Polarized look in post production. By selectively apply NIK Viveza Software to increase the saturation and contrast of an image and control the density (lightness and brightness) you can mimic a polarized feel.