A polarizing filter is like adding a pair of sunglasses to your camera. No, it won’t make your lens look cooler. But the way a polarizing filter adds a bit of punch to your outdoor images is definitely cool. Because polarizing filters adjust reflected light, they’re mainly used outdoors, but that’s not their only purpose.
But perhaps even more importantly, the effect of a polarizing filter can’t be mimicked in post processing. The adjustment of reflected light you get from a polarizer captures details that can’t be added in Photoshop later on.
So, what does a polarizing filter do, how do you use one, and what kind should you buy? A polarizing filter is one of the best filters for any type of outdoor shoot. Here’s what you need to know.
What does a polarizing filter do?
A polarizing filter removes light that has been reflected at a certain angle. This modification of reflected light allows for capturing clearer reflections off water, for example, or eliminating them entirely. Polarizing filters work with any reflective surface, like windows or a polished car. Shooting after a rainstorm, for example, a polarizer could be used to eliminate the reflections in the puddles or to enhance them.
But by cutting out reflections, polarizers actually have another purpose. Cutting out reflected light makes the remaining light more vibrant. The sky becomes a more dramatic blue, foliage becomes a deeper green and other objects appear more saturated as well. Polarizing filters are an essential tool for landscapes because of their ability to capture the sky in a deeper blue.
Since polarizing filters eliminate light, however, the image will be underexposed if the camera settings aren’t changed. Outdoors, that’s usually not a problem. Indoors, however, the polarizer can create a problem. The necessary drop in shutter speed to compensate for the loss of light often introduces motion blur indoors. For that reason, polarizing filters aren’t commonly used indoors. They can be used indoors to eliminate a reflection, however, if there’s enough light or the subject is still, like when shooting through glass at a museum.
How do I use a polarizing filter?
Most polarizers are circular, screw-in filters. A polarizing filter is actually two pieces of glass put together. The front piece rotates, while the other piece doesn’t. Rotating the front of the filter will change the intensity of the reflections, or the intensity of the color saturation effect.
When shooting with a polarizer filter, start by rotating the front of the filter and watching how the effect changes. Reflections will become more or less obvious; colors more or less saturated. Find the position that captures the effect you want for your particular image. You may want to enhance reflections, or you may want to eliminate them entirely.
But keep in mind polarizing filters block out reflected light at a certain angle. The position of the sun will actually affect how well the filter works. You may get a wide range, or you may not even notice a difference at all. Polarizers are most effective when the sun is about 37 degrees from the horizon. You’ll get more of an effect mid-morning and in the afternoon versus early morning, noon and late evening.
Changing the position of the filter (in other words the position of your camera) will also adjust the intensity of the polarizer’s effect. For a maximum effect, point the lens 90 degrees away from the sun. A well-known trick is to point at the sun with your index finger with your thumb up. Then shoot in the direction your thumb nail is pointing. Try moving the angle of your hand, while still pointing at the sun, to get different possibilities that still achieve the maximum effect. A simpler way to think of it is to keep the sun to one side of you, rather than directly in front or directly behind. Of course, you can use the polarizer at a different angle, especially if you’re not looking for the maximum polarizing effect.
Photographers should be careful when using a polarizer on a wide-angle lens, however. Because the lens covers more than that maximum 90 degree angle from the sun, the polarizing effect won’t be uniform across the entire image, resulting in a sky that’s a darker blue in part of the image and lighter in another. This can usually be fixed by shooting away from the sun, but you should always check the sky for this gradient look when using a polarizer on a wide angle lens.
What kind of polarizing filter should I buy?
Because polarizing filters involve multiple pieces of glass, they’re not the cheapest filters on the market, but their effect and wider range of uses certainly makes them worth the investment.
B+W makes excellent polarizing filters, but they’re also over a $100. If you shoot with a top-of-the-line camera, you may want to match your high quality lens with a high quality filter.
But, you can easily pick up a quality filter for under $50. Tiffen and Hoya are good options for filters within this price range.
As with purchasing any circular filter, you’ll need to purchase the size that fits your lens. The filter size is usually written on the inside of the lens cap.
Since polarizing filters are so effective and so versatile, you may want to pick one up for all your lenses, or at least the lenses you use the most. Of course, if you have lenses with a lot of different filter sizes, this can add up quick. To save money while still covering the entire range, buy a polarizing filter that fits your largest lens, then pick up a set of ring adapters. These adapters screw into the filter to make them fit a smaller thread size (do not use them to make a smaller filter fit a bigger lens). It is one more step, but may be worth the savings for some photographers.
Conclusion: Polarizing filters are one of the best filters to buy.
If you can only afford to buy one type of filter and you shoot outdoors, buy a polarizing filter. The ability to adjust the intensity of a reflection isn’t something that can be done in post processing, so the only option is to use a filter. Polarizing and neutral density filters are often necessary for shooting landscapes, though they certainly aren’t limited to just those applications.
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