CTO-021 Color Temperature Orange (Warming) Filter
Full CTO colour-conversion filter shifting 5600 K toward 3200 K for seamless mixed-lighting balance in broadcast, film, and architectural applications.
- Colour shift direction: Warming (5600 K → 3200 K)
- Mired shift: +131 Mired
- Correction strength: Full CTO
- Average transmittance: ~44.7 % T (visible range)
- Peak transmittance: ~82.8 % T near 779 nm
- Minimum transmittance: ~9.9 % T near 454 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-021 delivers a +131 Mired shift to move 5600 K light toward 3200 K. Its smooth spectral slope creates a natural warming effect, with about 44.7 % average visible transmittance and approximately 1.5 stops of light loss.
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Full daylight-to-tungsten conversion on HMI or daylight LED fixtures, mixed-light interiors, and scenes that need a strong warm match.
Description
CTO-021 produces a deep warm shift with its 50 % crossover at 600 nm, well into the orange region. Blue and green wavelengths are heavily attenuated: the blue band averages just 10.9 % and green averages 22.5 %. Transmission builds gradually through yellow (41 %) and orange (52 %) before reaching the red band at an average of 67.2 %. Peak transmission of 84.7 % occurs at 800 nm in the NIR. The overall profile delivers a strong amber-orange character with subdued maximum throughput, suited to effects where a deeply saturated warm wash is more important than raw brightness.
Key Advantages
- 50 % crossover at 600 nm (deep orange) - produces a heavily warm-shifted output with pronounced amber-gold character.
- Deep blue and green suppression (avg < 23 %) - removes nearly all cool-tone content for saturated warm colour.
- Gradually rising transmission to 84.7 % at 800 nm - maintains reasonable throughput in the deep red and NIR bands.
- Hard-oxide durability - ion-assisted coating withstands high lamp heat, humidity, solvents, and 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 and event lighting effects - creates deeply saturated amber and golden wash effects for sunset, firelight, and autumn scenes.
- Film and television mood lighting - adds a pronounced warm cast to practicals and background lighting for dramatic interior scenes.
- Architectural accent lighting - transforms neutral sources into warm amber highlights for heritage buildings, lobbies, and dining spaces.
- Photographic filtration - provides a strong physical warming filter for landscape and portrait photography under cool ambient conditions.
- Spectral shaping for horticulture - preferentially passes orange-red photosynthetically active radiation while suppressing blue-green wavelengths.
Need prototypes in days or production volumes next quarter? CTO-021 filters can be coated, diced, and shipped to your exact specifications.
FAQ
CTO-021 FAQ
What is CTO-021 and what is it used for?
CTO-021 is a Color Temperature Orange Filter - Deep Warm Shift (T50 % = 596 nm). CTO-021 produces a deep warm shift with its 50 % crossover at 600 nm, well into the orange region. Blue and green wavelengths are heavily attenuated: the blue band averages just 10.9 % and green averages 22.5 %. Common uses include Stage and event lighting effects, Film and television mood lighting, Architectural accent lighting, and Photographic filtration.
What are the key optical specs of CTO-021?
Key published specs for CTO-021 include Colour shift direction: Warming (5600 K → 3200 K); Mired shift: +131 Mired; Correction strength: Full CTO; Average transmittance: ~44.7 % T (visible range); Peak transmittance: ~82.8 % T near 779 nm.
What applications is CTO-021 best suited for?
CTO-021 is commonly used for Stage and event lighting effects, Film and television mood lighting, Architectural accent lighting, and Photographic filtration. Stage and event lighting effects - creates deeply saturated amber and golden wash effects for sunset, firelight, and autumn scenes.
Can CTO-021 be customized for size, substrate, or coating requirements?
KUPO lists the construction for CTO-021 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-021?
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
