light
Polarizing fi lters
Polarized light is the light refl ected from non-metallic surfaces and parts of the blue sky. A
polarizing fi lter can reduce this polarized light and the effects are visible when viewing the image
in the camera.
A polarizing fi lter is gray in appearance and when sold for camera use consists of the actual fi lter
mounted onto a second ring, thus allowing it to rotate when attached to the lens. The fi lter is
simply turned until the desired effect is achieved.
The polarizing fi lter is used for the following reasons:
~ Reducing or removing refl ections from surfaces
~ Darkening blue skies at a 90 degree angle to the sun
~ Increasing color saturation.
Possible problems
The fi lter should be removed when the effect is not required. If not removed the photographer will
lose two stops and reduce the ability to achieve overall focus.
When the polarizing fi lter is used in conjunction with a wide-angle lens, any fi lter already in place
should be removed. This will eliminate the problem of tunnel vision or clipped corners in the fi nal
image. Photographing landscapes when the sun is lower in the sky can result in an unnatural
gradation, ranging from a deep blue sky on one side of the frame to a lighter blue sky on the other.
ACTIVITY 7
Create an image on a sunny day eliminating polarized light and one without using the fi lter.
Try to remove refl ections from a shop window using a polarizing fi lter.
How effective is the fi lter at eliminating these refl ections?Mark Galer