Filters

Polarizing filters

Written by Bernard Dery

The polarizing filter is one of the most commonly used camera filters. When used correctly, it enhances photos in many ways.

Circular polarizerThe polarizing filter is one of the most commonly used camera filters. And there is good reason: it enhances photos in many ways.

When used correctly, a polarizer will reduce or eliminate glare from reflective surfaces such as glass and water. It can also deepen the color of skies. Overall color saturation, especially outdoors, can significantly improve.

Using a polarizer

No polarizerPolarizers, like other filters, have standard threads and come in a variety of diameters. Their characteristic feature is their front element, which rotates so that its orientation varies. As the front element is rotated on its axis, the polarizing effect varies.

The first thing to identify when using a polarizer is the position of the blocking axis, often identified by a small white marking on the side to identify that axis. That marking is not always accurate, so rotate the polarizer and watch changes on the monitor until the desired effect is achieved.

Using polarizers with point-and-shoot cameras

Using PolarizerWith a DSLR, using a polarizing filter on lenses with a non-rotating front elements is easy: simply look in the viewfinder and adjust the polarizer until the picture looks good. With point-and-shoot cameras, using a polarizer is trickier, but still fairly easy.

First, remember to only use the LCD or electronic viewfinder. That’s because a point-and-shoot’s optical viewfinder doesn’t look through the lens and doesn’t show the effect of the polarizer.

Half-press the shutter of your camera so that exposure is locked. If you don’t lock exposure, the camera will compensate any change by brightening or darkening the LCD, and the effect of the polarizer will be hard to evaluate.

While still holding the shutter half-pressed, rotate the polarizer and you will see its effect on the image. When the polarizer is correctly adjusted, release the shutter, half-press again and take the picture.

Polarizing filters and light source

A polarizers effect will be strongly influenced by the position of the light source. Many other elements can influence the effectiveness of a polarizer, so keep an eye for desired changes.

Even if using a polarizer initially seems complicated, it quickly becomes natural and you’ll  learn to anticipate its effect. Practice is all that’s needed!

When not to use a polarizing filter

  • Use of a polarizer is not suitable for all shots, so don’t leave one attached to your camera at all times.
  • Do not use a polarizer in low light as the polarizer will decrease the amount of light reaching your sensor by about half.
  • Do not use a polarizer if the sky is overcast.
  • Generally, there is no real advantage of using a polarizing filter indoors.

Benefits of using a polarizer

  • regular light sources will see their intensity decreased by half, as if you were using a Neutral Density filter
  • reflections on non-metallic surfaces can vary from almost zero intensity to full intensity depending on the orientation of the polarizer; water and glass can appear to be completely transparent
  • foliage will gain deeper and richer colors; overall staturation will improve
  • blue skies will become deeper, clouds will be better contrasted, and you will reduce the risks of overexposing the sky
  • contrast between rainbows and the sky will decrease or increase depending on the polarizer’s orientation

Use a polarizing filter only if you have a specific purpose in mind. Understanding how a polarizng filter works may seem complex and learning to use it can take some time. But the results are very rewarding. As with everything, practice makes perfect!

Additional points:

  • If using the polarizer with a lens wider than the equivalent of a 28mm lens, the polarization of the sky may be uneven.
  • The effects of polarizers are very hard to duplicate with software because they change the properties of the light beams passing through them.

Photo illustrations by Bernard Dery

About the author

Bernard Dery

Bernard was born and still lives in Quebec City, Canada. A doctorate candidate in Physics, Bernard works full-time as an optical designer at EXFO, a world leader in telecom tests and measurements tools. His professional interests go from fiber optics to atmospheric data collection and lasers.

His first contact with photography was a Vivitar fixed lens camera that he had purchased at age eight. His interest developed slowly, and for many years Bernard limited himself to family and travel pictures.

Bernard discovered the world of digital photography in February 2004, when he purchased his first digital camera. Developing an interest for composition, he experimented with many subjects: landscapes, nature, cities and architecture.

Bernard
soon began to invest more time and energy into his new found hobby, finding new and beautiful subjects to capture everyday. His challenge is to capture the mood and emotion carried by a scene as it presents itself to him.

A trip to Italy in
September 2004 fueled his growing interest with numerous magical photography opportunities.

Bernard and his wife like to spend free time near a lake at his family's summer house, where he finds new subjects to capture every day. His interests are varied and include hiking, camping, swimming, boating and reading, as well as most winter
sports.

Bernard, known as bdery on forums, uses a Pentax K20D and W80, Canon S2 and a Nikon SQ as a backup.

Thumbnails are of photos by Bernard Dery - used with permission
Copyright Bernard Dery All rights reserved