CTO-028 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: ~63.1 % T (visible range)
- Peak transmittance: ~96.3 % T near 745 nm
- Minimum transmittance: ~32.5 % T near 389 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-028 delivers a +35 Mired shift to move 5600 K light toward 4500 K. Its smooth spectral slope creates a natural warming effect, with about 63.1 % 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-028 combines a moderate CTO crossover at 553 nm with exceptionally high long-wavelength throughput, peaking at 96.3 % at 745 nm. The NIR band (700-800 nm) averages 95.9 %, the highest in the CTO series for this crossover range. Red transmission averages 89.1 %, yellow sits at 58 %, and blue-green wavelengths are held to 33-34 %. The smooth, monotonically rising transmission curve from blue through NIR produces a clean warm shift with no spectral dips or secondary features, making CTO-028 an efficient, broadband warm-conversion filter with outstanding red and NIR performance.
Key Advantages
- 50 % crossover at 553 nm with peak of 96.3 % at 745 nm - combines moderate colour-temperature shift with the highest NIR throughput in the CTO series.
- NIR band averaging 95.9 % - delivers near-perfect infrared throughput, critical for applications requiring both warm visible and NIR transmission.
- Smooth, monotonic spectral curve - produces a clean warm shift without spectral artefacts, ripple, or secondary absorption dips.
- 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 entertainment lighting - provides a moderate warm shift with maximum output efficiency, ideal for large-venue wash fixtures.
- Day-night imaging systems - warms the visible colour palette while maintaining near-perfect NIR transmission for combined day/night camera operation.
- Colour-corrected NIR illumination - allows red and NIR illuminators to operate at peak efficiency while simultaneously warming residual visible output.
- Film and broadcast production - delivers a standard half-CTO colour correction with minimal light loss at any wavelength above 600 nm.
- Solar simulation and testing - shapes broadband lamp output toward the warm end of the solar spectrum while preserving NIR content for complete spectral simulation.
Need prototypes in days or production volumes next quarter? CTO-028 filters can be coated, diced, and shipped to your exact specifications.
FAQ
CTO-028 FAQ
What is CTO-028 and what is it used for?
CTO-028 is a Color Temperature Orange Filter - Moderate Warm Shift with High NIR (T50 % = 553 nm). CTO-028 combines a moderate CTO crossover at 553 nm with exceptionally high long-wavelength throughput, peaking at 96.3 % at 745 nm. The NIR band (700-800 nm) averages 95.9 %, the highest in the CTO series for this crossover range. Common uses include Stage and entertainment lighting, Day-night imaging systems, Colour-corrected NIR illumination, and Film and broadcast production.
What are the key optical specs of CTO-028?
Key published specs for CTO-028 include Colour shift direction: Warming (5600 K → 4500 K); Mired shift: +35 Mired; Correction strength: 1/4 CTO; Average transmittance: ~63.1 % T (visible range); Peak transmittance: ~96.3 % T near 745 nm.
What applications is CTO-028 best suited for?
CTO-028 is commonly used for Stage and entertainment lighting, Day-night imaging systems, Colour-corrected NIR illumination, and Film and broadcast production. Stage and entertainment lighting - provides a moderate warm shift with maximum output efficiency, ideal for large-venue wash fixtures.
Can CTO-028 be customized for size, substrate, or coating requirements?
KUPO lists the construction for CTO-028 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-028?
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
