Lux: unit of illuminance measuring how much light falls on a surface, equal to one lumen per square meter.
Definition
Lux is the SI unit for illuminance. It measures how much light falls on a surface. One lux is equivalent to one lumen per square meter.
Practical Application
Lux values determine exposure settings on set:
- Exposure Metering: Spot meters display lux values for precise camera settings
- Lighting Design: Different lux values create different moods
- Continuity: Consistent lux values for matching shots
- Actor Comfort: Eye-friendly light levels above 500 lux
Technical Details
Typical lux values in film:
- Candlelight: 1 lux
- Moonlight: 0.1 lux
- Office lighting: 400-500 lux
- Daylight overcast: 1,000 lux
- Daylight sunny: 10,000-100,000 lux
Practical Tips
- Calibrate lux meters before each shooting day
- Multiple measurement points for even illumination
- Consider camera ISO settings when measuring lux
- Include reflections from walls and objects in the measurement
Professional Standards
Broadcast standards define minimum lux values:
- HD production: at least 200 lux on faces
- 4K production: at least 400 lux for optimal image sharpness
- Interview setups: 800-1200 lux for natural skin tones
- Chroma key: 2000+ lux for clean keying
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