Polarizing filters are among the most important filters in both analog and digital photography. Since they are rotatable in their mount, the effect of polarization can be visibly adjusted in the viewfinder or on the display. Another effect of B+W polarizing filters is the reduction of reflections on non-metallic surfaces such as water, shop windows, and paint. Objects behind these surfaces, including text behind reflective paint, become visible again—providing a fascinating image enhancement without the need for post-processing. B+W polarizing filters are circular polarizers that take into account the different measurement systems of cameras. This is the case with almost all modern cameras when beam splitters are involved in the TTL exposure meter or autofocus light path. This helps to avoid exposure errors.