In order to talk about a circular polarizer, you have to understand its purpose, what it works with.
Lets start with light. Light has many sources, could be the sun, a light bulb, or maybe even a reflection. Light travels out or emanates from its source. It radiates or travels out in a wave; it flows out randomly and in all directions. Light can be reflected, like off of a wall, glass, metal or even off of water. Imagine light traveling horizontally and vertically also in circular patterns clockwise and counterclockwise. By this I mean the light is almost on several different planes.
In photography, trying to capture a picture or image light is always present, in some form. You may or may not be happy with how the light is falling on your vantage point. It may be necessary to filter out the light to intensify work, it maybe necessary for clarity of an object. Your goal may be to enhance the color. It may be a goal to project more depth in an image. To do this, you would have to be able to control the pattern of light. Well thats exactly what a circular polarizer does. The word filter comes to mind. Allowing certain things in or keeping certain things out. In our case, it is light. With the circular polarizer, I am able to capture the light traveling in a certain pattern or it may even be thought of as having the abillity to block scattered light or atleast to be able to adjust it like a beam to make my enhancements. With the circular polarizer, I am in control of the tool in my arsenal to get the results that I need, feeling confident that I have achieved my goal in creating my perfect shot.
Hoya, a world leader in the production of polarizing filters has set the standard for excellence in the polarizing filter market. Hoya has been producing specialized optical glass since 1941 and they have it down to a fine science.
The purpose of polarizing filters is to filter the light rays that enter your camera lens. This filtering eliminates undesired reflections, increases color saturation and enhances contrast. The result is a clearer, more detailed picture. A Hoya polarizing filter is often used to enhance the contrast between blue skies and white clouds, but the filters do not alter the actual color balance of a photograph.
Hoya polarizing filters are also used to prevent undesired reflections from non-metallic surfaces like water and glass.
Hoya produces two kinds of polarizing filters: linear and circular. Linear Polarizing and Circular Polarizing filters have the same effect. Choosing the correct one will depend upon your camera recommendations.
Hoya polarizing filters are made with a hardened 8-layer waterproof multi-coating that is both scratch and stain resistant. This coating allows an average light transmission rate of greater than 99% on average distance shots. This impressively reduces reflections that bounce off the surface of the glass and enable you to capture greater light in your photographs.
Serious photographers should always carry a Hoya polarizing filter in their camera case. Great for outdoor shots, these polarizing filters are made for most types of cameras, from the medium format to the digital type point-and-shoot. Single lens reflex cameras with Autofocus require the Hoya circular polarizing filter, which allows front-side rotation.
Whatever the light or reflection challenge, the professionals at Hoya have created polarizing filters that can eliminate the problem. Consider making one part of your camera gear.