What is the difference between a Linear and a Circular Polarizer?
A Circular Polarizer is a Linear Polarizer with a 1/ 4 wave plate retarder added to the back of the polarizer foil. Circular Polarizers are necessary when using an SLR that has a beam splitter which is used for internal light meter reading. The beam splitter polarizes light and depending upon the position of the polarizer, you may cause double polarization and therefore result in inaccurate meter readings. Circular Polarizers are also necessary for auto focus cameras. TIP: In any case in which linear polarizing filters suffice, circular polarizing filters can also be used, but not the other way around. A detailed description of the physics of the way linear and polarizing filters work can be found here. Linear polarizers are also referred to as Top polarizers on our web site and in our literature.
