Distance from light source to subject; determines intensity, shadow hardness, and falloff following the inverse square law.
Definition
The Throw Distance refers to the distance between the light source and the illuminated object. This distance determines light intensity, shadow hardness, and illumination characteristics.
Practical Application
The Throw Distance influences the following parameters:
- Light Intensity: Doubling the distance reduces illuminance by 75% (Inverse Square Law)
- Shadow Hardness: Greater distance creates harder, defined shadows
- Beam Angle: Distance changes the diameter of the light circle for spotlights
- Color Temperature: Atmosphere can cause color shift at large distances
Technical Details
Calculation bases for practical use:
- Illuminance decreases quadratically with distance
- Fresnel lenses alter light distribution depending on focal length
- LED panels show a uniform decrease without hotspot shift
- HMI lights require a minimum distance for optimal light distribution
Practical Tips
- Measure exposure at different distances
- For Fresnel spots, set the focal length before changing position
- Observe safety distances to flammable materials
- Plan cable routing for long distances
Professional Standards
Standard distances in film production:
- Key Light: 2-4 meters for natural shadow falloff
- Fill Light: 3-6 meters for soft fill
- Background Light: 4-8 meters for even illumination
- Effect Light: Variable distance depending on desired intensity
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