circular polarizer - need help

[snapper27]

I see that you are able to acheive beatiful blue skies with a circular polarizer...
can someone explain How whe and why to use one...thanks

[robertwgross]

Normal sunlight tends to be unpolarized. That means that the rays are hitting you with completely random orientation. A polarizer cuts out half of the rays and lets half through. So, the sky looks "cleaner" and "bluer" to my eyes. It should make the white clouds look whiter and contrast better against the sky.

The effect will be seen the most if you are pointed close to 90 degrees away from the sun. Then rotate the filter around until you see the degree of polarization that you want.

---Bob Gross---

[felix21685]

kind of like a red or yellow filter for b&w film eh ? but also reduces glare

[d'homme]

Point your finger at the sun. With your thumb up, turn. All the area that your thumb points to will be polarized with the polarizer.

[etaf]

it will also reduce reflections.
there are two types of polariser
1) linear
2) circular

depending on the camera focus system which one you need to use - I know on the EOS5 that a linear polarier is supposed to interfer with the focus - although I have had some success with the linear version

[nat869]

I have just started playing with one myself, it is pretty neat. It also works to cut glare coming off of water. These pics were taken with the 50 1.8 and a Tiffen circ. polarizer.

http://photography-on-the.net/forum/showthread.php?t=76629

actually they were taken in the evening, around 9pm.