There are many available filters out there to help improve your landscape photography, but there is one filter that every photographer should have in their camera bag, and that is a polarizing filter. A polarizing filter can be used in both color and black and white photography and it will help you produce beautiful outdoor photos.
The main effect of a polarizing filter is that it eliminates the reflection from non-metal surfaces. It will enhance the colors in your photographs, making them rich and deep in color. No other filter is able to do that. When taking pictures of trees, leaves, foliage, etc., the polarizing filter will help them to appear less shiny.
A polarizing filter is most effective with skies, color enhancement, water and reflective surfaces, and light absorption. By eliminating the reflection of light, the polarizer produces saturated and slightly darker skies. The filter tends to enhance colors by making shadow areas darker. By eliminating reflections, the filter tends to make water and various other reflective surfaces more transparent. A side effect of the polarizing filter is that it absorbs 1.5 stop of light, so in low lighted situations, some type of camera support will be needed to develop the most effective photos.
Polarizing filters typically come in two types- screw-in filters or fitting one into a square filter. Screw-in filters are the right way to go if you typically use one lens, or if all your lenses have the same filter thread. When buying a polarizer that fits into one of the square filter systems, the Cokin A or P ranges are ideal for the small diameter lenses. The Lee filter system is very adaptable so it will fit almost any lens, including large diameter angle lenses and medium format cameras.