Rosco 101

Overview

"Rosco 101" refers to diffusion filter #101, designated "Light Frost", from the Roscolux line by US manufacturer Rosco. It is not a light source, a lamp code, or grip equipment, but a diffusion filter sheet (colloquially "gel") placed in front of a light source to soften the beam.

Within the Rosco diffusion family, #101 is one of the weakest grades (the "Light" variant). Its effect is therefore subtle: the light beam is slightly softened without significant loss of throw or brightness. Stronger diffusion grades in the same series carry numbers like #102 (Light Tough Frost) or #103 (Tough Frost).

Properties and Effect

According to manufacturer and dealer descriptions, #101 provides a softened beam and transforms the hard field of an ellipsoidal/profile spotlight into a flood, more even light field ("changes ellipsoidal into flood or scoop"). It diffuses the light slightly, smooths beam edges, and reduces hard shadow edges without altering the color temperature – #101 is a pure diffusion, not a color or conversion filter.

• Function: light diffusion / beam softening
• Line: Roscolux (Rosco)
• Color Character: neutral, no color correction
• Typical Application: soft edges, gentler shadows, more even field

Available Formats

The filter is offered in the standard Roscolux sheet and roll formats:

Use on Set

The #101 is used when a spotlight appears "too harsh" but only minimal correction is desired – for instance, to imperceptibly break the edge of a profile spotlight or a spot. Due to the low diffusion, light loss is minimal, which is why the filter is used as a "fine grade" between "unfiltered" and stronger diffusion. In practice, it is inserted as a sheet in filter frames in front of PAR, Fresnel, or profile spotlights, or cut from the roll. Roscolux filters are dyed-through or multi-layer extruded polyester, making them more heat-resistant and color-stable than simple dyed filters.