Remove unwanted reflections from non-metallic surfacesImprove color saturation, clarity and contrastProvides protection for your lens while shootingDesigned especially to benefit wide angle lenses and avoid vignettingTreated with a multi-layer coating process to optimize protectionOverviewThe Sigma Ex DG Circular Polarizer 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 contains a quarter wave plane in addition to the linear polarizing filter. The addition of this quarter wave plane is to circularly polarize the linearly polarized light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polarizer, auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarized, it permits the use of these functions.This filter has a wide filter mount to help reduce the likelihood of vignetting when working with wide-angle lenses. It is constructed from optical glass and features Sigma's super multi-layer coating to reduce flare and ghosting while helping to increase overall clarity and contrast.Helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surfacePolarizing filters arrange, and filter, directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of the lightClears up haze in distant landscapes and provides more saturated, vivid colorsStrongest effect when used at a 90 from the sunCircular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus featuresWide filter mount minimizes vignetting when used on wide-angle lensesSuper multi-layer coating helps improve image clarity by reducing flare and ghosting