This article focuses on one of the most important pieces of the photographic toolkit, the polarizer. After a brief explanation of the principle behind its working, you'll learn the various benefits, limitations and disadvantages of using a polarizing filter on your digital camera's lens.
Polarizing Filters
You've probably read in magazines or seen on websites that the one most essential accessory any photographer should have is a polarizing filter. Most photographers would swear by one, and all photo-journals strongly recommend one. What’s the big deal with the polarizer, anyway? And if it’s so indispensable, why don’t camera lenses come with a built-in polarizing filter? Read on to learn the good, the bad and the ugly of the most valuable camera accessory of all times.
The Good
Light, like all electromagnetic radiation, has a wave nature. Apart from wavelength and frequency, another characteristic of light waves is their plane of rotation, or ‘polarization’. Normal light comprises waves polarized in various angles - vertical, horizontal and everything in between. Now, if we pass this light through a linear polarizing filter, all but one plane of light is cut off. The resulting light is devoid of interfering waves, and hence an image obtained through a polarizing filter appears without haze, giving the famous ‘deep blue sky’ effect.
The two images below illustrate the effects a polarizing filter can have on your photos (click any image to enlarge). The image on the left was taken without a polarizer, where the one on the right was taken with.
The Advantages of Using a Polarizing Filter
1. Water and other partially reflective surfaces often reflect a linearly polarized part of randomly polarized light much more strongly than others. Using a polarizing filter to block this off cuts off the glare and allows one to see beneath the surface of the water, which is fantastic if photographing aquatic life (just be sure you don't get your camera wet!).
2. Removes haze and gives the sky a deep blue colour.
3. Makes the clouds 'pop out'!
4. Cuts off reflections from glass, metals or shiny surfaces, like a sandy beach on a sunny day, giving clearer, glare-free photos.
5. Cuts reflections from surfaces like leaves or walls, making colours appear saturated, and shadows appear blacker.
6. Can be used as an effective ND filter (neutral density filter), especially in bright sunlight.
Notice how using the polarizer cuts back on the reflection of water and one can see beneath the surface too.
Photo credit: Mike Baird
Please continue on to page 2, where you will learn the cons of using a polarizing filter.