The Heliopan 105mm Circular Polarizer Slim Filter helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. This results in a noticeable increase in the saturation of skies and foliage, as well as clearer imagery when photographing in hazy conditions. A circular polarizer differs from a linear polarizer in that it supports full use of a camera's autofocus and auto exposure functions. The front and rear surfaces of the filter both feature a single anti-reflection coating. Each coating helps to increase light transmission by reducing reflections, scattered light, and ghosting. Additionally, they offer protection to the filter substrate while helping to keep the glass clean for longer than uncoated glass. This Heliopan filter is constructed from Schott glass for increased optical clarity and color fidelity. It features a slim brass filter ring for durability as well as jamming prevention. Its 5mm-thick profile does not have front threads in order to minimize the likelihood of vignetting with wide-angle lenses.