Pixiq

If someone told you that they could sell you a single lens filter that could darken blue skies, saturate colors, remove surface reflections (including window reflections), intensify rainbows, and reduce haze—would you buy it? You bet you would. And a polarizing filter can do all of those things and, at times, seem like an almost magical accessory.

A polarizing filter is one of the most versatile and important photo accessories that you can own and, even though I use one less with digital cameras than I did with film cameras (I’ll explain why in a minute), I still use one regularly. In the simplest of terms, polarizing filters work by blocking certain wavelengths of light from entering the lens and allowing others. They have a rotating mount that screws to the front of your DSLR lens; as you rotate the filter, it blocks different wavelengths. There are several things that polarizing filters do superbly well:

• Darken blue skies: Polarizing filters block extraneous scattered light reflections in the atmosphere and can be used to darken blue skies. I use them less for this than I used to with film cameras because I can create the same effect in editing and have somewhat more control. I also feel that polarizing filters tend to over darken skies with digital cameras if you’re not careful about exposure and the exact rotation position. Sky darkening works best when the sun is to the right or left of your shooting position, and not at all when the sun is behind or in front of you. You can see the effect in the viewfinder as you rotate the filter and as you alter your position in relation to the light.
• Saturate colors: When you rotate the filter, the colors of things like leaves and grass or people’s clothing becomes more (or less) saturated. This is the main thing that I used to use polarizing filters for, but again, I can saturate colors more selectively in editing. Still, I will sometimes use a polarizing filter with landscapes where I want to control the color saturation at the time I’m shooting.
• Eliminate reflections: This is something you can’t do very easily in editing! You can remove reflections from any nonmetallic surfaces just by rotating the filter. If you’re shooting a store window display, for example, you can penetrate the reflections to reveal what’s behind the glass.
• Reduce atmospheric haze: Polarizing filters are much more efficient at reducing haze (not fog) than so-called “UV” (ultra-violet) filters, and they’re essential in landscape photography for that reason.
• Intensify rainbows: No joke! By reducing the atmospheric haze and by blocking certain wavelengths of light, you can strengthen the colors of a rainbow substantially.

If you’re using autofocus lenses, be sure to buy a “circular” filter, but check your lens or camera manual to be sure of the and type and size in terms of diameter that you need.