Diffusion
Diffusion is a colorless gel that changes the shape of the beam of light. Diffusion comes in two different main types: Frost and Silk.
Neutral Density gels decrease the transmission of light without affecting the color.
Neutral Density gels decrease the transmission of light without affecting the color.
Frost
While the edge of the beam of light can be softened by adjusting the focal length (running the barrel), by using frost the designer can make sure that all of the edges are equally fuzzed. Frost is a colorless polyester filter found in the gel book that rather than changing the color, scatters somewhat the light that passes through it. Think of a pebbled window that you might find in a bathroom. Each of the little bumps in the glass bends the light somewhat, therefore scattering the light passing through the window in such a way that there is not a clear view of what is on the other side. The same is true of frost filters. Some (like R132) scatter the light just a little, leaving the beam of light mostly intact but softening an otherwise sharpened edge. Others (such as R116) spread out the light so much that the beam is almost unrecognizable on the stage, turning the light into a directional flood source.
Because frost is normally colorless, it is often added to a gel frame in addition to a cut of color media. On the light plot and in paperwork, the designer should specify the inclusion of frost by presenting the color as Color + Frost (example: L728 +R132).
Because frost is normally colorless, it is often added to a gel frame in addition to a cut of color media. On the light plot and in paperwork, the designer should specify the inclusion of frost by presenting the color as Color + Frost (example: L728 +R132).
silk
Silk, on the other hand (such as R104) is a directional media which 'stretches' the beam of light in order to make it more oblong rather than round. Silk is often used with cyc cells in order to help the systems blend together. It is also a good way to light narrow areas, such as theatre aisles.
The silk gel has a visible grain which determines the direction of the stretch, but it is a little counter-intuitive, because in order to get a horizontal beam such as the one shown at right, the electrician must insert the silk with the grain going vertically.
Similar to frost, silk can be added to a frame with color, and is noted on the plot and paperwork as the example: G848+R104.
The silk gel has a visible grain which determines the direction of the stretch, but it is a little counter-intuitive, because in order to get a horizontal beam such as the one shown at right, the electrician must insert the silk with the grain going vertically.
Similar to frost, silk can be added to a frame with color, and is noted on the plot and paperwork as the example: G848+R104.