CTO-018 Color Temperature Orange (Warming) Filter
1/4 CTO colour-conversion filter shifting 5600 K toward 4500 K for seamless mixed-lighting balance in broadcast, film, and architectural applications.
- Colour shift direction: Warming (5600 K → 4500 K)
- Mired shift: +35 Mired
- Correction strength: 1/4 CTO
- Average transmittance: ~63.2 % T (visible range)
- Peak transmittance: ~93.8 % T near 642 nm
- Minimum transmittance: ~20.6 % T near 475 nm
- Construction: Ion-assisted hard-oxide; 5 – 450 mm shapes, 0.21 – 3.8 mm thick
- Custom options: Intermediate Mired shifts, combined CTO+diffusion, custom sizes, rapid prototypes
Learn more
CTO-18 delivers a +35 Mired shift to move 5600 K light toward 4500 K. Its smooth spectral slope creates a natural warming effect, with about 63.2 % average visible transmittance and approximately 0.3 stops of light loss.
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Light warming for white-balance fine-tuning, subtle skin-tone warmth, and gentle golden-hour style looks.
Description
CTO-018 delivers a moderate color-temperature shift with its 50 % crossover at 552 nm. Blue wavelengths (450-495 nm) are strongly suppressed to an average of 21.5 %, while red transmission (620-700 nm) soars to an average of 92.7 % with a peak of 93.8 % at 642 nm. The NIR band (700-800 nm) maintains 88.9 % average throughput. A notable violet shoulder at 380 nm (70.9 %) adds a touch of warmth complexity. The result is a confident warm shift that converts a 5600 K daylight source noticeably toward the 3200-3800 K range.
Key Advantages
- 50 % crossover at 552 nm - places the colour transition at the green-yellow boundary for a natural-looking warm conversion.
- Peak transmission of 93.8 % at 642 nm - delivers high orange-red efficiency, minimising output loss.
- Strong blue suppression (avg 21.5 % at 450-495 nm) - substantially reduces cool-tone energy for a convincing warm palette.
- Hard-oxide durability - ion-assisted coating survives high lamp temperatures, humidity, solvents, and repeated cleaning.
- Custom formats available - round, square, or free-form blanks from 5 mm to 450 mm, thickness 0.21-3.8 mm, on Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG substrates.
Typical Applications
- Stage lighting colour correction - converts daylight LED or HMI fixtures toward tungsten-equivalent colour temperatures for warm scene design.
- Film and television production - balances mixed lighting environments by warming daylight sources to match practical tungsten fixtures on set.
- Architectural and retail lighting - transforms cool-white LED panels into warm-white sources to suit hospitality, residential, and boutique environments.
- Photography colour grading - provides a physical warm filter for in-camera colour shifts without post-production processing.
- Machine vision with orange-band emphasis - enhances contrast for inspection tasks where orange-red features must stand out against cooler backgrounds.
Need prototypes in days or production volumes next quarter? CTO-018 filters can be coated, diced, and shipped to your exact specifications.
FAQ
CTO-18 FAQ
What is CTO-18 and what is it used for?
CTO-18 is a Color Temperature Orange Filter - Moderate Warm Shift (T50 % = 552 nm). CTO-18 delivers a moderate color-temperature shift with its 50 % crossover at 552 nm. Blue wavelengths (450-495 nm) are strongly suppressed to an average of 21.5 %, while red transmission (620-700 nm) soars to an average of 92.7 % with a peak of 93.8 % at 642 nm. Common uses include Stage lighting colour correction, Film and television production, Architectural and retail lighting, and Photography colour grading.
What are the key optical specs of CTO-18?
Key published specs for CTO-18 include Colour shift direction: Warming (5600 K → 4500 K); Mired shift: +35 Mired; Correction strength: 1/4 CTO; Average transmittance: ~63.2 % T (visible range); Peak transmittance: ~93.8 % T near 642 nm.
What applications is CTO-18 best suited for?
CTO-18 is commonly used for Stage lighting colour correction, Film and television production, Architectural and retail lighting, and Photography colour grading. Stage lighting colour correction - converts daylight LED or HMI fixtures toward tungsten-equivalent colour temperatures for warm scene design.
Can CTO-18 be customized for size, substrate, or coating requirements?
KUPO lists the construction for CTO-18 as Ion-assisted hard-oxide; 5 – 450 mm shapes, 0.21 – 3.8 mm thick. Published custom options include Intermediate Mired shifts, combined CTO+diffusion, custom sizes, rapid prototypes. Custom formats available - round, square, or free-form blanks from 5 mm to 450 mm, thickness 0.21-3.8 mm, on Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG substrates.
What should I know about angle of incidence and durability for CTO-18?
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
