How to Use a Circular Polarizer Filter

Although digital photography has many many old-school film filters obsolete, a few remain very useful. One of these is the circular polarizer filter.

The circular polarizer adds dramatic effects to your photographs. It's one of the tricks that professional photographers rely on to create brilliant images with rich color and dynamic contrast.

How a Polarizing Filter Works

Put simply, a polarizer reduces the amount of reflected light that goes to your camera's image sensor. It cuts out the junk light and haze of the atmosphere and allows the camera to capture a clearer, crisper photograph.

If you've worn polarizing sunglasses on a sunny day near a body of water, you've seen what polarizers do. They deepen the blues of the sky and make clouds seem to pop out from the background. They remove reflections off the water's surface, allowing you to see deeper into the water than without your glasses. Likewise, winter scenes have more depth because reflections off the snow are neutralized. The polarizing filter has the same effect on a camera.

Polarization is most effective at 90 degrees to the sun or other light source. Maximum polarization occurs when your subject is at a right angle to the sun. At 180 degrees (when the sun is behind you), polarization is non-existent. Between these two points, the amount of polarization varies.

How to Use a Polarizing Filter

A circular polarizing filter screws onto the front of the camera lens and has two rings that rotate. To use a polarizer, simply twist the front ring to activate polarization.

Set your focus, then find the point of maximum polarization. This helps because the front ring of the lens that the polarizer is attached to can rotate as it focuses and throw off the polarization. Even if you have to refocus after polarizing, the filter should still be in the general alignment that you left it (unless you change focus points).

Tips

Practice with reflections and blue skies while getting used to the polarizing filter. Take some photographs of the same scene at maximum polarization and without polarization, and compare the two. The difference should be dramatic.

Once you become aware of the effects of polarization, you'll likely find creative uses beyond the utility of shooting skies, water, and reflection.

If you have multiple lenses with different filter sizes, you might be able to get away with a single polarizing filter. As long as the differences among the filter sizes aren't too drastic, a step-up or step-down ring will work. These inexpensive adapters come in various sizes and can be used to fit, for example, a 58mm filter onto a lens that takes 52mm filters.

The Drawbacks of a Polarizing Filter

Using a polarizing filter reduces the amount of light reaching the camera's sensor by as much as two or three f-stops, so you must adjust for this in one of these ways:

• Choose a slower shutter speed (and use a tripod, if needed).
• Open up by choosing to a lower f/stop.
• Add more light to the scene—at the same angle, if possible.

Low light conditions are not ideal for using a polarizing filter. If you want to cut reflection late in the day or highlight clouds at sunset, use a tripod.

Choosing a Polarizing Filter

Polarizing filters are not cheap, and quality is just as important with your filter as with your lens. High-quality glass produces the sharpest photographs.

Linear vs. Circular Polarizing Filters

Polarizing filters are available in two types: linear and circular. Linear polarizing filters are used for manual-focus film cameras. Although they can polarize light more dramatically than a circular polarizer, they can damage your camera's electronics.

In contrast, circular polarizers were developed to work with autofocus lenses and complex electronics.