Product Description
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
settings.
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.
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
exposure/aperture readings.
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