Ron Hashiro

When light is reflected from particles in the sky or the surface of the water, the direction of the light waves (otherwise known as polarization) is changed from a random pattern and becomes uniform. By using a special light filter called a polarizer, one can selectively accept or reject light that is polarized from exposing the film. It is the same type of material used in Polaroid sun glasses to screen out glare.

The selection is made by rotating one of the elements of the filter. If you have your back to the sun, point the filter at the blue sky and rotate the filter, you will see the sky progressively darken then lighten. You can use it to deepen the color of the blue sky in your photos. Below, we have the sky and landscape of Kapaa on Kauai without a polarizer.

Here we have the same scene, same exposure (plus one stop overexposure to compensate for the polarizer) and same scanning method. I did wait a few moments for the sun to illuminate the broad plain in the distance to make it a more interesting photo I also turned the camera vertically to capture more sky so you can see the effect deepens as you look higher in the sky.

The polarizer can be used to cut out the glare on the surface of water, enabling you to see the river bed or ocean bottom below. You can also cut out the glare reflected from windows and shiny metal, for example.

There are two basic styles of polarizers. The older "linear" polarizers are used extensively with manual focus cameras, but will cause an autofocus camera to operate improperly. For autofocus cameras, use a "circular" polarizer.

With a circular polarizer, the amount of polarizing effect remains the same regardless of how much the lens or lens filter rotates during the autofocus operation. The same is not true with a linear polarizer.

I hope this short introduction gives you an idea of the everyday situations when you could use a polarizer.

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since June 9, 1997