The Heliopan 77mm Circular Polarizer improves the color of the sky, (in distant pictures, mountain scenes, etc.) and reduces the bluish cast in landscapes. The darkest blue sky is achieved photographing objects at a 90° angle to the sun. In addition, polarizers enhance the color saturation of the scene by suppressing reflections from the subject"s surface. Undesired reflections can largely be eliminated. The rim is calibrated to help in finding the proper setting when a through-the-lens preview is not available. Suitable for use with auto-focus cameras, cameras with through-the-lens metering and digital cameras.