The angular spread of a fixture's light cone — determines the size of the illuminated area.
Definition
The Beam Angle refers to the angle of a spotlight, measured between the two points where the light intensity drops to 50% of its maximum value. It determines the size and shape of the illuminated area.
Practical Application
The Beam Angle is used for targeted lighting control:
- Spotlights: Narrow Beam Angle (5-15°) for hard, concentrated illumination
- Flood Lighting: Wide Beam Angle (40-80°) for broad area illumination
- Background Light: Medium Beam Angle (20-40°) for selective area lighting
- Effect Lighting: Variable angles for specific light shapes
Technical Details
Important parameters for measurement:
- Measured in degrees (°) at 50% light drop-off
- Field Angle: Measurement at 10% light drop-off (always larger than Beam Angle)
- Dependent on reflector geometry and focal length
- Adjustable by focusing or changing lenses
Practical Tips
- Check the Beam Angle on the monitor before shooting begins
- Use a light meter to verify light distribution
- For LED panels: Beam Angle often adjustable with diffusers or lenses
- Maintain a safe distance from objects with narrow Beam Angles
Professional Standards
Standardized Beam Angles enable:
- Reproducible lighting setups across multiple shooting days
- Precise advance planning of lighting
- Efficient communication between the gaffer and the team
- Continuity in matching shots
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