This ProMaster 77mm Pure Light filter can be used to remove or control reflections, improve contrast & saturation, or darken blue skies. It also protects your valuable lens against the elements such as sand, dirt, oil, water, and even fingerprints. Thanks to a special combination of hydrophobic coatings, finely polished SchottTM B270 optical glass, and top-of-the-line polarizing films Pure Light CPL filters have a high light transmission rating, very low light reflectivity, and are color neutral. This equates to a pure transfer of the image to your camera’s digital sensor or film while gaining the creative benefits of a circular polarizing filter. Not only do these filters offer excellent protection for your lens against sand, dirt, oil, water, and fingerprints; but they are also easy to clean. Plus, any camera’s auto focus system works perfectly with a Pure Light CPL. Each Pure Light filter has a matte black coating applied to the very edge of its glass before being carefully set into its anodized aluminum frame. This reduces the possibility of internal reflections as light passes through. All ProMaster Pure Light filters have the same size filter thread on the front and back. So, they are compatible with your lens cap, and they can be stacked with other, same-size filters. They also come in a terrific, eco-friendly snap case. This case serves two purposes It provides minimalist packaging. It acts as a storage case for your filter when not in use. ProMaster Pure Light filters are crafted with care and precision in Japan. Why use a CPL filter? A CPL is one of the most highly used filters in both still photography and videography, and with good reason. The effects of a polarizing filter are difficult or sometimes impossible to imitate in post-production software. These effects can be used to create beautiful compositions. A CPL can: Control reflections and/or reduce glare on non-metallic surfaces. I.E. water, glass, glossy paint, etc. Improve color saturation and contrast. Deepen/darken the blue color of skies. Reduce the appearance of atmospheric haze when photographing distant objects and landscapes.