Flag refers to an opaque panel placed in the path of a light beam to block or shape all or part of the illumination, sometimes also referred to as a filter or gobo depending on size and regional terminology.
A Flag is a light control accessory used in professional lighting environments to block, shape, or limit illumination from a fixture. It is typically constructed from opaque fabric stretched over a metal frame or from other nontransmissive materials designed to prevent light from passing through. By positioning a flag within the beam path, lighting professionals can control spill, reduce glare, or isolate specific areas of a scene.
Flags are commonly square or slightly rectangular in shape, with typical dimensions ranging from approximately 10 inches to 48 inches in length and 12 inches to 48 inches in width. The size selected depends on the scale of the lighting setup and the amount of beam control required. Smaller flags provide precise blocking of narrow beam sections, while larger flags can obscure entire fixtures or prevent light from striking walls, ceilings, or background surfaces.
In broadcast studios, corporate production facilities, training environments, and performance venues, flags are used to refine lighting balance. They may be positioned to prevent unwanted light from reaching camera lenses, reflective surfaces, or adjacent set elements. In some cases, flags are also used to conceal lighting fixtures positioned in darker areas of a scene while maintaining intended illumination on the subject.
Terminology can vary regionally. Some professionals may refer to certain light blocking devices as gobos or filters depending on their construction and intended use. However, in this context, a flag specifically denotes an opaque blocking panel rather than a patterned projection device.
From a systems perspective, flags contribute to controlled light distribution and predictable visual outcomes. By managing beam boundaries and reducing unintended spill, they support consistent lighting design in commercial and industrial AV environments where precision and visual clarity are required.