Chances are, you have a high-quality polarizing filter with you at all times, right under your nose. (Actually, it's sitting on your nose.)
Next to a fully charged battery and a huge memory card, a polarizing filter is the digital photographer's best friend. It reduces unsightly glare, deepens the richness of skies, and improves overall color saturation.The problem for most shooters on the go is that they don't always have their full kit of accessories with them. And many point-and-shoot cameras don't even provide a way to attach an external filter, even if you wanted to.
So what's a photographer to do? Does this mean you'll have to suffer with glare-y subjects and desaturated skies, just because you want to tote a convenient digicam instead of lugging around an albatross of a camera bag? Not at all. Your solution is sitting there right on top of your nose. Your sunglasses! Great lighting usually results in good photographs, with or without filtration, as shown. But sometimes you want to enhance an already good lighting situation. Often, polarization is the perfect solution, as shown . If you don't have a polarizing filter with you, try your sunglasses. You might be surprised by the results.
Without Sunglasses Filter
Using a Sunglasses Filter
Many quality shades are made out of the same material that camera polarizers are made out of. Simply take off your sunglasses and place one lens as close to your camera's shooting lens as possible. Then, take the shot. If you want to see the difference, take the same.
Source: O'Reiley | Online Portfolio Websites for Photographers