Circular Polarizer - Arrived

Ok I feel really stupid asking this question. I just purchased a circular polarizer but I'm curious why does the filter spin? I would think a gradient filter to spin but what is the reason behind this feature.

Thank you.

"Just turn its front part to adjust the effect and watch it appear in the viewfinder.
Remember that the effect is stronger when you have the sun at 90° on your left or right. It will be less visible with the sun in your back and almost non-existant with the sun in front."

http://www.offrench.ne​t …les/polarizing_​filter.php

Polarized glass is directional. It stops light vibrating at one direction, while allowing light vibrating at right angles to that to pass. Since you don't always know which direction you want the light to be vibrating, you need to spin it. Point it at a subject and watch as you rotate the filter.

Look through the view finder at the sky and spin it.

Since its obvious by your post that you've never used one before, here's a tip: when looking through the viewfinder, be sure to rotate the filter in the CCW direction...there's less of a chance for you to accidentally unscrew it and have it fall to the ground.

Thanks for the tips. Appreciate everyones help, never knew they worked that way.

argyle wrote in post #5618467
Since its obvious by your post that you've never used one before, here's a tip: when looking through the viewfinder, be sure to rotate the filter in the CCW direction...there's less of a chance for you to accidentally unscrew it and have it fall to the ground.

I spin mine this way as well, just to be safe.

You can look a right twat when spinning the filter the wrong way, and it falling to the ground.
Ben
" All the gear, but no clue!"