Placing the polarizing filter “Outside” of the filter pack polarizes the light for all of the subsequent filters yielding the richest color possible.The Schneider 5.650 x 5.650 square Circular Pol can brighten up your scene and reduce harsh flares. A must have filter for your kit.Schneider offers a circular True-Pol Polarizing filter for cameras which use polarizing elements in the beam-splitters of the viewing system, such as ARRI 435 and the Movie-Cam Compact. This filter may also be required on certain high definition video cameras with complex optical blocks such as the Sony PMW-EX1, PMW-EX3, and PDW-700 which polarize the red an blue channels more than other cameras and therefore require a circular polarizer to prevent cross polarization and associated color shift in the image.Beam splitters send light in two directions: to an eye-piece and to a video tap. Light in a cameras viewing system can become polarized, and when a standard (linear) polarizing filter is attached to the lens, the light becomes cross polarized. This hinders visibility and may create total black-out of the viewing image and/or the video tap.Schneider Circular Polarizers feature a two layer design to prevent this blackout. The first layer is made up of the same polarizing material used in all True-Pol filters; the second layer is a 1/4- wave retarder plate which effectively prevents cross-polarization.