The polarizing filter used with most modern cameras is a circular polarizer. The first stage of the polarizer is a linear filter which filters out light that is linearly polarized in a specific direction. The second stage, for technical reasons related to the auto sensors within the camera, then circularly polarizes the light before it enters the camera.

The polarizing filter has two applications in both color photography and black-and-white photography: it reduces reflections from some surfaces, and it can darken the sky.