Spill

Definition
Spill refers to unwanted or uncontrolled light emanating from a light source that falls outside the intended area of illumination. The spill angle is typically measured in degrees – for a 2K Fresnel fixture, for example, the main beam angle is 12-60°, while spill can deviate up to 180°. The term was established in the 1920s with the introduction of professional studio lighting.

Technical Details
Spill is caused by reflections off housing parts, incomplete shielding of the light source, or scattering by particles in the air. HMI lights, due to their point-source nature, produce significantly more spill than LED panels with a diffuse emission characteristic. The spill value is measured in lux – while the main light might reach 10,000 lux, spill is typically around 50-500 lux. Barn doors reduce spill by 60-80%, snoots by up to 95%, while egg crates on LED panels achieve a reduction of 70%.

History & Development
With the first arc lamp studios around 1915, the problem of uncontrolled light was already recognized. In 1927, Mole-Richardson developed the first barn doors for Fresnel lights. The term "spill" became established in Hollywood in the 1930s. Modern LED technology since 2010 enables more precise light control through pixel mapping and electronic dimming of individual LED chips.

Practical Application in Film
In "Blade Runner 2049," Roger Deakins used controlled spill from practical neon lighting for atmospheric spatial definition. In interviews, barn doors are used to keep spill away from the background and achieve subject separation. Conversely, unwanted spill causes flat contrasts and destroys the plasticity of the lighting – a spill value of 2% can already raise the black level by half a stop.

Comparison & Alternatives
Spill differs from diffused light in that it occurs unintentionally and uncontrollably. While bounce light is used intentionally for soft illumination, spill is usually disruptive. Modern Aputure LED lights use honeycomb grids with 20°, 30°, or 45° beam angles. CineFlex curtains made of black molton absorb 99% of spill and are increasingly replacing heavy flag constructions.