Sigma EX DG - Filter - circular polarizer - 52 mm - for Sigma DP3 Merrill

The Sigma 52mm DG Multi-Layer Coated Wide Circular Polarizer Filterhelps to reduce reflections and glare by filtering out light that hasbecome polarized due to reflection from a non-metallic surface. Thisresults 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 itcontains a quarter wave plane in addition to the linear polarizingfilter. The addition of this quarter wave plane is to circularlypolarize the linearly polarized light for the use of auto focus andexposure functions. Due to how the light is broken down and filteredwith a linear polarizer, auto focus and exposure accuracy become skewedduring use. When the light becomes circularly polarized, it permits theuse of these functions.

This filter has a wide filter mount tohelp reduce the likelihood of vignetting when working with wide-anglelenses. It is constructed from optical glass and features Sigma's supermulti-layer coating to reduce flare and ghosting while helping toincrease overall clarity and contrast.