This is one of those things that can really make a difference. A small detail, yet extremely important in particular circumstances.
I polarizer only allows light to enter the lens from a particular direction. While light from a source is always omnidirectional, as well as most light bouncing off an object, some reflected light is coming from a single direction. See these examples:
Both of these are unedited out of the camera. The difference is amazing, and the difference is between an amateur and a professional. I almost always have a circular polarizer on my lens. For only $50-$100, it makes and enormous difference. Watch out though. You don’t always want to use one, they make the image much darker, so they’re bad in low light situations.
Here’s another example:
Look at the effect on the clouds / sky and the removal of the reflection off the water. If you don’t have one, get one. It will be way worth it. Everyone and their pet dog asks me what kind of camera to buy. I tell them the camera is the least important thing to buy. This is one of the important things.
DTX Media – Dallas Photography