Parallel metal strips mounted in front of a fixture to collimate the beam and reduce lateral spill.
Definition
A louver is a light modifier with parallel slats designed to control the direction of light from luminaires. The slats block light entering from the sides and create a directed beam of light.
Practical Application
Louvers are used for:
- Spill Control: Preventing stray light from hitting unwanted areas
- Contrast Enhancement: Targeted illumination of specific image areas
- Background Separation: Separating foreground and background
- Flagging Replacement: Alternative to individual flags with multiple light sources
Technical Details
Construction features:
- Slat spacing determines beam angle (typically 10°, 20°, 40°)
- Attachment via standard accessory rail on the luminaire
- Materials: Aluminum or plastic with a matte black coating
- Light loss: 0.5 to 1 stop depending on slat angle
Practical Tips
- Repeat exposure measurement after louver installation
- Regularly check slats for bending
- On LED panels, be aware of moiré effects caused by the slat pattern
- Transport in foam padding to protect the slats
Professional Standards
Standard sizes are based on luminaire diameters:
- Fresnel luminaires: 150mm, 200mm, 300mm diameter
- PAR luminaires: PAR36, PAR64 specific versions
- LED panels: Rectangular louvers according to panel dimensions
- Softboxes: Integrated louvers as honeycomb structures
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