Viewing this before and after polarizing filter photo is a great way of seeing how significant certain filters can affect photographs.
Polarizing filter enhance color saturation and reduce reflections.
I first learned about polarizing filterers as a young boy. My father turned me on to photography when I was in elementary school and I've been hooked ever since.
Check out this dramatic before and after polarizing filter comparison. Depending on the angles, a polarizing filter can completely change an image. In this case, I actually prefer the photo without the polarizing filter on the left.
The left half of the photo shows the pond grass photographed without a polarizing filter. I combined that with the right half of the photo of the same subject taken with a polarizing filter attached to get the maximum amount of reflection reduction.
Which photograph do you like better? That's subject to interpretation. There are certain instances when using one of these filters is clearly desirable and others where no filer gives the more interesting image.
I found a very similar situation here where the photo using the filter is superior to the photo without. With the polarizer used you can clearly see the frog remarkably better.
1. Must be circular. Circular polarizers allow you to rotate the filter without unscrewing it from your lens. Since the direction of light changes may change with the situation you're in, it is essential to be able to rotate the filter to control the amount of polarization you want to achieve.
2. Must be multi-coated. Lenses themselves will reflect and scatter light, resulting in degradation of image quality. Properly coated lenses give much better image quality.
3. Pricing. You get what you pay for and buying a really cheap polarizing filter will give you disappointing results. Read the reviews of actual, real buyers:ACTUAL CONSUMER REVIEWS OF POLARIZING FILTERS ON AMAZON
Buying a used filter is not such a bad idea, provided you are buying from a trusted source and provided that the filter is perfectly clean and has no scratches. Filters don't "wear out" like cameras or batteries.
If you take good care of them, you'll never need to replace them, unless you switch lenses to a different size. I've personally never bought a used filter, but that doesn't mean you can't.
I read lots of reviews and then buy new.LINK TO BEST-SELLING POLARIZING FILTERS
Have a blast with Digital Photography!