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. Exposure compensation is about two
f-stops.
Linear and circular
polarizers both consist of a linear polarizer foil but differ in their
construction in the following way. Modern DSLR cameras 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 polarizer
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.
MRC - A Special Scratch-Resistant, Water and Dirt Repelling Coating
The left half of this filter has a
traditional coating. The right half
has MRC coating.
The
lens elements of high-quality lenses and the plano surfaces of filters
require a perfect shape and smoothness to
achieve the best optical quality. Dirt, greasy fingerprints, water
marks and scratches reduce the image contrast and the sharpness, which
can result in blooming at light sources and have an effect similar to a
soft-focus lens. A clean front lens element and clean filter surfaces
are therefore an absolute pre-requisite for demanding photographers.
The
MRC coating is first and foremost a broadband anti-reflection coating.
This means that its reflection-reducing
effect, which is thus also a transmission-increasing effect, i.e. one
which suppresses scattered light and ghost images and transmits more
light, has a broadband action over the full spectrum. In contrast, the
(almost always blue) single-layer coating only has a high effect in the
medium wavelength range around yellow and yellow-green where the eye is
most sensitive to light, while its
effect is greatly reduced toward the blue-violet and purple-red end
regions of the visible spectrum. With the MRC coating, this blue, violet
and red to deep-red light cannot produce any contrast reducing
scattered light, spotty reflections or ghost images. A broadband effect
can only be achieved with a multilayer
coating which requires a much higher effort and precision because
unevenness and irregularities of the individual layers build up on one
another and amplify one another. Schneider therefore uses
a plasma-assisted evaporation coating process in which
inert gas ions accelerated in an electrical field
compact the material deposited on the lens surface in the
vacuum chamber.
For photographers,
the main advantage of MRC coating, is it's ability to combat flare and
ghosting. An added benefit is that their filters remain free of dirt
longer, so that they do not have to be cleaned so often. When cleaning
the filter does become necessary, it is a lot easier to wipe off the
dirt with a blower brush, because of MRC's ability to repel dirt and
moisture. This also reduces the risk of micro-scratches which can occur
during cleaning.
