Rotating a cpol filter

[Gazman]

Hi, i just recieved my new tiffen circular polarizing filter today.

I noticed it can be rotated. What does this achieve?
I thought the idea of a cpol filter was to cut glare and deepen blues.

Is it used for somthing else too?

 

[kundalini]

On a sunny day with filter mounted look at glass, water or any reflective surface. Slowly rotate the filter. See the change?

On a sunny day with white puffy clouds, slowly rotate the filter. See the change?

You're in control of how much to emphasize the effect.

 

[Village Idiot]

A polarizer cuts out polarized light. A circular polarizer cuts out polarized lights depending on the orientation of the glass to the polarized lights. That's why if it wouldn't rotate, you would have problems. Plus a lot of lenses have the front element rotate when you focus. This would royally screw with the operation.

So a polarizer with cut glar from polarized light and deepend blue(skies) by cutting down on the polarized light the camera is taking in through the lens. Those are just by products of the purpose of the filter.

Wikipedia polarizer and you'll see.

 

[kundalini]

Oh, one more thing..... you will get the greatest effect of the filter when it is 90° from the light source. Example: the sun rises in the East, sets in the West So if you point your lens with filter either North or South, that will give the most effect.

 

[Gazman]

thanks for replys