Highly efficient standard circular polarizing filter for all cameras with
beam splitters in the light paths of their TTL exposure meter and with autofocus
lenses. Circular polarization has the same pictorial effect as linear
polarization, but allows for proper exposure metering and/or autofocus distance
B+W Polarizers increase color saturation and reduce
reflections. The neutral gray color and plane parallel polarizer material
guarantee optimal image results. High-quality optical glass ensures excellent
pictorial quality. The filter factor varies according to how the filter is
positioned in relation to the sun. Filter factor is between 2.3 and 2.8.
MRC (Multi-Resistant Coating) by B+W is not only an extraordinarily effective
multiple layer coating, it is also harder than glass, so that it protects
filters from scratches (for instance when cleaning the filters), and it is also
water and dirt repellent, thus facilitating filter maintenance.
Linear and circular polarizers both consist of a linear polarizer foil but
differ in their construction in the following way. Modern SLR cameras have have
a beam-splitting prism that sends part of the incoming light to the meter and
part to the viewfinder. The effect is that the light entering the meter is
partially polarized by the beam-splitter. A linear polarized placed on the lens
of such a system will act as a second polarizer and block light to the meter by
a degree dependent on the angle between the prism and the polarizer on the lens.
The result is incorrect exposure/aperture values from the meter. The circular
polarizer circumvents this problem through the addition of a 1/4-wave retarder,
or delay, foil. This ensures that the linearly polarized light is changed into a
rotation that appears unpolarized to the meter, resulting in proper