What is commonly used to achieve a soft edge in lighting design?

Frost is commonly used in lighting design to achieve a soft edge because it scatters the light as it passes through, creating a diffused effect. This diffusion results in a softer transition between illuminated and shadowed areas, thus minimizing harsh lines. By controlling the intensity and distribution of light, frost can help create more visually pleasing and natural-looking lighting, which is particularly useful in theatre settings where mood and atmosphere are crucial to storytelling.

On the other hand, gels are primarily utilized for color correction or to create specific color effects rather than for softening the light's edge. Lenses, while essential for focusing light, do not inherently soften edges but can create sharper images depending on their type. Barndoors are used to shape the light beam and control spill, but they don't contribute to softening the edges of the light.