CTB (Color Temperature Blue) filter corrects warm tungsten sources to daylight-balanced Color Temperature.
Definition
Tungsten Correction refers to correction filters that adapt daylight film emulsions or digital cameras for tungsten light sources (3200K). CTO (Color Temperature Orange) filters lower the color temperature of daylight equipment to the tungsten standard.
Practical Application
CTO filters are used for:
- Color Correction: Adapting HMI or LED panels (5600K) to tungsten base lighting (3200K)
- Light Control: Harmonizing mixed light sources without post-processing
- Effect Design: Warm light accents through partial correction
- Workflow Optimization: Uniform color temperature on set reduces color grading effort
Technical Details
- Standard Strengths: 1/8, 1/4, 1/2, 3/4, Full CTO
- Light Loss: 1/3 to 2/3 stops depending on filter strength
- Mounting via filter frame, clip-on holder, or in a matte box
- Material: Polyester film or glass for continuous use
Practical Tips
- Perform exposure measurement after filter attachment
- 1/4 CTO is often sufficient for subtle harmonization
- Protect filters from heat exposure - maintain minimum distance from lamps
- Can be combined with ND filters for double correction
Professional Standards
CTO filters are standard equipment for:
- Consistent color reproduction in mixed lighting situations
- Quick light adjustment without changing lamps
- Cost reduction through less post-production
- Broadcast-compliant color temperature standards
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