|
Rosco Roscolux
Roscolux is comprised of two types of plastic. More than 65% of the line
is made from co-extruded polycarbonate plastic. The remainder of the
line is deep dyed polyester. Sheets: 20 x 24" Rolls: 24" x 25'
How Colour Filters Work
Filters create colour by subtracting certain wavelengths of colour.
Thus, a red filter absorbs blue and green, allowing only the red
wavelengths to pass. The process is subtractive, not additive, so the
light source must emit a full spectrum.
The Rosco swatchbook provides detailed information on the spectral
energy curve of each filter. The curve describes the wavelengths of
colour transmitted through each filter. For example, Supergel 342
transmits approximately 40% of the violet and blue energy of the
spectrum and 75% of the orange and red energy. It absorbs all energy in
the yellow and green range.
Durability
The life of colour filters depends on many variables: the colour, the
instrument and lamp used, the dimmer level a filter generally runs at,
and the amount of time the light is running. For these reasons it is
impossible to assign a "life" for each filter. However some basics
knowledge and experience can help with estimates. Dark green and dark
blue filters usually burn out the fastest because they absorb the most
infrared energy. Absorbing the extra infrared energy causes the plastic
to reach it's melting temperature faster. When darker filters are needed
try choosing filters that transmit high amounts of the 700 nm range. You
can find this information by looking at the Spectral Energy Distribution
(S.E.D.) curve located in the swatchbook for each Supergel colour
filter. Filters than transmit high levels at 700 nm may also transmit
high levels in the infrared range above 700 nm.(See the Supergel
swatchbook for information on how to read S.E.D. curves.)
To prolong the life of a colour filter, align your ellipsoidal lamp to a
flat field focus. (Get rid of the hot spot.) You can increase the
distance between the lamp and the filter by using a top hat or barn
door. In extreme cases, try Rosco Heat Shield or Thermashield to prolong
the life of your filters.
 |
Download
Colour Filter Guide |
 |
View
Roscolux Colour Filters |
|
