IR ND Filters
12:43:00
Today's Digital cameras are capable of recording light from the full spectrum (visible and invisible light) - 300 to 1200 mm. Without infrared filtration, cameras record images that are effectively superimposed versions from both visible and near infrared (NIR) light.
Light transmitted to the sensor, therefore increases substantially. And since infrared gets recorded by all three color channels, color saturation typically decreases accordingly which creates adverse effect on the quality and the color rendition of the images - stealing contrast and color, resulting in unwanted color shifts. Greens become a reddish muddy brown and blacks have a magenta cast.
Neutral Density (or ND) filters are neutral gray and reduce the amount of light reaching the film or digital sensor. ND filters are used to control exposure time and depth of field without effecting color or contrast. IRND filters remove infrared. The IR attenuation reduces digital artifacts and color shifts caused by infrared contamination on the digital sensor.
To overcome this problem, some camera manufacturers use an IR blocking filter in front of the imaging sensors. But now professionally Filters are made to filter full spectrum infra red - IR ND Filters designed to provide a true neutral density and maintain color balance.
IR NDs are also manufactured available in ND.3, ND.6, ND.9, ND1.2, ND1.5, ND1.8 and ND2.1
These filters are made with Water White glass and are available in sizes 4x4, 4x4.650, 5.65x5.65, 6.6x6.6,138 mm.
Author:
CJ Rajkumar
Author/Cinematographer
1 comments
Very useful information
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