Why use a polarizer

[Albie]

I am still on the learning curve with my FZ30, and a friend of mine has given me a load of filters, including a polarizer, what I would like to know is basically ... why and when would I want to use a polarizer.

The other filters he has included are some ND filters, sepia filters, and graduated filters ... so at some point I will have to get around to experimenting with them as well.

[JLV]

Polarizer help to reduce glare and reflections. May also darken the sky.

[kgosden]

Actually a polarization filter can both decrease or increase reflections on glass or water. The effect is relative to the angle of the sun and the position of the camera. The ability to sometimes eliminate reflections on windows is one thing that is nearly impossible to duplicate in post processing. You can almost always add a reflection, but to see through one to the contents behind the reflection is not possible later. There are times where the reflected image is what you might want to capture. Then a polarization filter can enhance that reflection. Most reflections from metal and chrome surfaces are unaffected.