Mine saved my life when a bluff I was standing on collapsed dropping me 25′.

http://www.traviswilliams.net/eds-story-on-4029/

Don’t restrict yourself to using a polarizer only on sunny days or before the sun goes down. For example, consider shooting a fall foliage scene in the Smoky Mountains with a stream and bolders in very low light. Even though the sun can’t be seen, there are image-killing reflections coming from the sky, especially on overcast days.

If you rotate the polarizer with no change, take it off as every filter, no matter how expensive, is going to rob some sharpness from the image.

Be sure to use a very thin polarizer with wide angle lenses and consider using a “warming polarizer” on overcast days. Even though digital can be post-processed and it is generally required, make the best image possible when you shoot. Don’t sound like the person who just fell of the turnip truck (I live in the South) by saying something stupid like “the image is just a building block and I will fix it in Photoshop.” If you don’t have the necessary understanding of exposure, composition, “seeing,” etc. you will just have a piece of crap “building block” that will probably look even worse after hours of Photoshop work. Shoot smart and process little.

Good shooting.
Charlie

Here’s a little trick I’ve learned from my best friend: If you’re shooting at a slightly slower shutter speed, carefully jiggle the gnd up and down for a much smoother transition between the dark and light sections.