Most major filter makers, including Lee, Cokin, B+W and Hoya, produce a plain red filter
, ideal for black and white infrared photography.
Rather than having a red filter
which affects all parts of the image, the system finds those areas which are red and makes them white.
Typical RGB filters cover around 100-150nm in bandwidth and a red filter
of 100nm bandwidth will be less affected by dispersion than a blue filter of the same bandwidth.
Light that passed through a red filter
as well as light from a filter that shows the glowing hydrogen gas, were coloured red.
The filter's effect on the object's luminance depends on the transmission spectrum of the filter and the spectral power distribution of the object, eg a red filter
will make green objects appear dim but it will only have a small effect on red objects.
Burns, who was out 'lamping', shot Mr Lawson after his binoculars were picked up in a friend's red filter
A red filter
can be used to reduce the traffic light effect caused by the Earth's atmosphere and will also improve contrast.
BBC producer Jeremy Daldry said the dome, housing plants and flowers, looked amazing in its temporary red nose incarnation, created by the use of red filter
lights beamed from inside.
We added a red filter
to the M900 light and left the Universal Light as our white light source.
Although the red filter
reduced the intensity of the light at all wavelengths (luminous transmission 22%) detection thresholds improved by about 0.
Observe, for instance, preschoolers given some toys purchased at a novelty store: a large sponge shaped and painted to look like a rock, a "sucker" egg made of chalk, and a green cardboard cat covered by a removable red filter
that makes it appear black.
One camera uses a near-infrared filter, one uses a red filter
, and the third is equipped with a yellow-green filter.