Filter Question

[focuspocus]

I bought a Sigma 17-70 today along with a polarizing filter which I have never used before. Is a polarizing filter used for reducing reflection in water or did I buy the wrong one?
Froggie here has a lot of reflection in the water so I think I messed up. Which one should I have bought?
Thanks for helping out a beginner.

[Wilt]

Teresa, did you turn the filter for maximum effect?

Polarized light is 'directional'...the waves of light that make up the reflection are mostly oriented in one axis. The polarizing filter is turned 90 degrees to that orientation to block those light rays, thereby removing the reflection.

[focuspocus]

Thanks Wilt! Didn't know you were supposed to turn it. Man I have a lot to learn.

[Wilt]

Take the filter in your hand and look thru it as you rotate it. If you look at light reflections in window glass that is at an angle to your position, you should see the intensity of the reflection change as the filter rotates. That illustrates one of the uses of the polarizer.

Now, holding the filter in your hand, aim up to the blue sky and rotate the polarizer. At certain angles to the sun, the effect as you rotate the filter is minimal. At other angles to the sun, the effect is quite dramatic at darkening the sky. This illustrates the other major use of the polarizer.