The B+W CPOL E 52 is a circular polarizing filter designed for cameras with beam splitters in their TTL exposure metering systems and autofocus lenses. With a diameter of 52 mm, this filter provides the same visual effects as linear polarizing filters while ensuring precise exposure measurement and autofocus functionality. Made from high-quality optical glass with neutral gray coloring and plane-parallel polarizing material, it delivers optimal image quality with enhanced color saturation and reduced reflections. The filter factor ranges from 2.3 to 2.8 depending on its positioning relative to the light source. Circular polarizing filters incorporate a 1/4-wave plate that converts linearly polarized light into rotational polarization, thereby avoiding exposure metering errors that often occur with linear polarizing filters on modern DSLRs. This technical solution ensures reliable performance with autofocus systems and TTL metering while maintaining the polarization benefits for photographic applications. The robust construction and precise processing guarantee lasting functionality and optical precision under various operating conditions. As a filter with a 52 mm diameter, this model is suitable for a wide range of camera lenses and provides photographic control over reflections and contrasts in different lighting situations.