Cokin Creative Filter A164 Circular Polarizer

Cokin filters were invented by professional photographer Jean Coquin. By using square filters like Cokin's, which fit into a holder and are attached to a lens via an adapter ring, the photographer has a number of immediate advantages. There is no need to duplicate filters to fit lenses of different sizes, up to three filters can be used at once to create unique effects, and the photographer has control over the positioning of the effect on the photograph.

Light rays which are reflected by any surface become polarised and polarising filters are used to select which light rays enter your camara lens. They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also saturate colors and increase contrast. Polarizers come in two variations but have the same effect. Linear polarizers work with older camera meters; circular polarizers are designed for today's newer slpit-beam metering systems used in auto focus cameras; check your camera's manual. A160 Linear Polarizer A164 Circular Polarizer

1 Circular Polarizer
If you don't have a polarizer, stop reading this and get one! I use a polarizer on almost every shot with a blue sky. Without a polarizer, blue skies appear a tepid, light blue on film; with a polarizer filter, they come out in a rich, deep color. The filter works by cutting out reflected glare and it's also useful for water (lakes, ponds), window glass, and tree leaves. A polarizer is more expensive than most other filters but worth the investment.

Regardless of the type of shooting you do, a polarizer is the most useful and versatile filter you can own. It's a very visual filter with which to work: As you rotate it in its mount, the effects are immediately noticeable. A polarizing filter can deepen the color and contrast in a sky (the most intense effects are always 90Ą from the sun or light source), eliminate glare from wet or reflective surfaces and cut through atmospheric haze to increase clarity and contrast in a scene. Since the effect of a polarizer is most pronounced when it is used perpendicular to the light source (the sun usually), try this trick... Make an "L" with your thumb and forefinger. Point your forefinger at the sun and your thumb will point in the direction that the polarizer will have its greatest effect. You can rotate your thumb around the axis of your forefinger, pointing the lens in any of these directions will let you take full advantage of the polarizers capabilities. Polarizers have little or no effect when they are used in the same direction as the light source.

Polarizers come in two varieties: Linear 160 and Circular 164. Each has the same effect visually; the difference is just in the way they polarize the light passing through. If you own an auto focus or auto-exposure camera (basically any modern camera), use a 164 Circular polarizer, which won't interfere with its automatic functions. Digital cameras in general do not have reflection mirrors, and, as a result, can use both (linear or circular) polarizers. A Polarizer tends to cool down the image. I find adding a Warm filter will restore warmth and a more natural image.