Circular Polarizers

Buying filters can be confusing, especially if you go to a store that has a lot manufacturers and models in its offer. Seeing all those small filter cases can be very misleading, so that's why we've put together this series that teaches you all you need to know about filters.

This time we're talking about one of the most important filters you can buy, one that every photographer should own: the circular polarizer.

What is a circular polarizer? Let's start with how it looks. It's a round filter, like most on the market, with a darker glass element. It goes screw mounted on the front of your lens. The key difference in how a polarizer is built is a ring around it that you turn for polarizing, depending on what you have in front of your camera.

What does a circular polarizer do? Let's break everything down separately.

If you're shooting a scene with a portion of sky in it, the circular polarizer will change the way everything looks dramatically. That's because the special glass changes the way your camera sees light entirely. To help you get a better idea of what I'm talking about, it's a little like wearing sunglasses. So what it will do is change color and contrast, turning a pale blue sky into a vibrant, blue colored one.

It is a filter that generally increases saturation no matter what you photograph, but you will feel that a little more on greens and reds.

But perhaps the coolest trick polarizers can do is eliminate reflections. Seriously, it's almost like magic. Let's say you want to shoot a portrait of somebody sitting in a car, behind the well, and you want to take the picture from outside the car, through the windshield. Try it without a polarizer mounted and you will see all the light reflecting back from the window to your lens, making your subject almost invisible. Mount a polarizer, spin the ring while looking through the viewfinder and you will see the magic happen with your own eyes. This filter enables you to see subjects that are behind glass, water or other reflective objects. It is probably the only filter available on the market the effect of which cannot be replicated using Photoshop or any other processing software.

Like most filters, polarizers come in different price ranges. The more affordable versions will do their job, but they might not eliminate reflections completely, nor will their coating layers last very long. The more you pay, the more you get from a filter. That's way the pricey models have more coatings on the glass element, they are scratch proof and are built to last a lot longer.

Finally, there is one important aspect that you need to keep in mind when using circular polarizers. Just like sunglasses make things a little darker, so do polarizers for your camera. They affect exposure, usually by no more than three stops. Remember this when mounting one on and also when taking it off. Good luck!