Lighter straw-colored filter for subtle warm correction — reduces blue content by approx. 1650K instead of full 3200K. Used for fine color balancing between daylight and tungsten sources.
Technical Specifications
Color Temperature Shift:
- Shift: approx. 150-200 K towards Tungsten
- Mired Value: approx. -50 to -65 Mired
- Output Temperature: Fluorescent (approx. 4200-4500 K) is shifted to approx. 3800-4200 K
- Additional Components: Magenta/Straw tone for green cast compensation
Optical Properties:
- Light Loss: approx. 0.4 to 0.55 f-stops
- Transmission: approx. 95-96%
- Special Feature: Non-neutral color shift (straw color for fluorescent correction)
Application
The 1/2 CTS filter is specifically used for:
- Fluorescent Light Correction: In offices, schools, factories, supermarkets with fluorescent tubes
- Mixed Lighting with Fluorescent: Combination of Tungsten and fluorescent light
- Sodium Vapor Lamps: CTS also helps neutralize the yellow-green cast here
- Studio Setup with Fluorescent Ambient Light: When external sources cannot be controlled
- Alternative to Electronic WB: Physical filter for more consistent colors across all takes
Manufacturers & Products
Lee Filters:
- Lee 209 (Half CTS) - Standard size 0.5m x 1.22m
Rosco:
- Rosco 3204 (CTS 1/2 Strength) - Standard size
Tiffen:
- 1/2 CTS (available as Cut-Gel)
Arri:
- CTS 1/2 (for professional integration)
Practical Tips
- CTS vs. CTO: CTO is for Daylight-to-Tungsten correction. CTS is specifically for fluorescent light with its typical green cast. Do not confuse them!
- Full CTS vs. 1/2 CTS:
- Full CTS (1/1): For a strong green fluorescent cast
- 1/2 CTS: For more moderate fluorescent situations or when Full CTS appears too yellow
- Combination with Green Filters: 1/2 CTS is often combined with a Plus Green or Minus Green to correct the green cast even more precisely:
- CTS + Plus Green: When the fluorescent green cast is very dominant
- CTS + Minus Green: For finer adjustment
- White Balance Setting:
- Manual: 4000-4200 K
- Preset: Fluorescent mode (if available) + additional filter
- Storage: CTS filters can yellow if exposed to direct UV radiation. Store cool and dark.
- Practical Sizes: 1/2 CTS is available as
- Full-frame filters for large luminaires
- Cut gels for spots
- Gel rolls for continuous lighting
- Measurement: When choosing between Full and 1/2 CTS, a color temperature measurement is helpful (Color Meter). This way, you know exactly which strength you need.
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