Rodenstock Circular Polarizing Filters.
Natural light is made up of electromagnetic waves in all possible oscillation
directions of equal occurrence. When light is incident obliquely
onto electrically non-conductive surfaces, the different oscillation directions
are reflected with different intensities; the light is called “polarized”.
How much it is polarized depends on the angle of incidence
of the light. At 0° (perpendicular incidence), no polarization occurs; at
an angle of incidence of around 35° to 40°, polarization reaches its
maximum and reduces again with a shallower incidence of light.
What do polarizing filters do and what is changed in the image?
Polarizing filters only allow oscillations to pass in a single polarization
plane; only those portions of other oscillations are transmitted which
are parallel thereto. A polarizing filter transmits almost 50% of natural
light. The compensation factor of around 2.5 required to compensate
for this is automatically taken into account in the TTL exposure
measurement. Polarized light from reflections, in contrast, is attenuated
more or less or even fully eliminated depending on the rotation of
the filter; however, it may also be (relatively) amplified. The greater
the shine of the surface, the clearer this effect becomes. With a matt
finished surface, the color saturation improves (clearer natural color).
How can the photographer best use polarizing filters?
The example photos show how a polarizing filter can “magic away”
irritating
reflections from a pane of glass or from the object itself. The
photographer can see how to turn the polarizing filter for ideal attenuation
or elimination through the viewfinder of a single-lens reflex
camera or on the LCD monitor of other digital cameras. He or she does
not need any special physical or technical knowledge.
What are the advantages of circular polarizing filters?
Circular polarizing filters are linear polarizing filters with an additional
“l/4 plate” which converts the light leaving the filter into circularly
polarized light. This is necessary in cameras with a beam splitter to visualize
a portion of the light for the TTL exposure measurement or
autofocus
measurement. These cameras namely also cause polarizing
and, depending on the rotation of the polarizing filter, would attenuate
or block the light diverted for the measurement and would result
in overexposure or would prevent focusing. Circular polarizing filters
are an absolute necessity for single-lens reflex cameras.
Why Rodenstock polarizing filters?
A high-performance polarizing film free of veiling and with a neutral
color effect ensures no loss of image definition as well as unaltered
colors and the lowest possible light loss.
This polarizing film and the l/4 layer are cemented between absolutely
planoparallel glass plates to avoid reflections at the glass/air interface
as well as further light losses and scattered light.
Both outer surfaces are incredibly smooth, hardened and MC coated.
The slimline, rotatable mount is so unobtrusive that it does not cause
any vignetting even in shots with very short focal lengths.
It has a front thread for a lens hood and a lens cap.
