CTO-048 Color Temperature Orange (Warming) Filter
1/2 CTO colour-conversion filter shifting 5600 K toward 3800 K for seamless mixed-lighting balance in broadcast, film, and architectural applications.
- Colour shift direction: Warming (5600 K → 3800 K)
- Mired shift: +67 Mired
- Correction strength: 1/2 CTO
- Average transmittance: ~55.5 % T (visible range)
- Peak transmittance: ~95.8 % T near 712 nm
- Minimum transmittance: ~3.5 % T near 439 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-048 delivers a +67 Mired shift to move 5600 K light toward 3800 K. Its smooth spectral slope creates a natural warming effect, with about 55.5 % average visible transmittance and approximately 0.7 stops of light loss.
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Moderate warming when daylight and tungsten need to blend, especially for interview lighting, event rigs, and warmer skin tones.
Description
CTO-048 is the most unique filter in the CTO series, with its 50 % crossover at 411 nm - deep in the violet region. This creates an ultra-wide warm passband that starts passing light from approximately 477 nm onward, with a deep blocking notch at 430-449 nm (T < 5 %). The green band averages 22.7 %, building steadily through orange (35.4 %) and red (83.8 %) to peak at 95.8 % at 712 nm. NIR averages 93.9 %. The profile behaves more like a green-notch longpass than a traditional CTO, creating a broad warm filter with particularly strong red and NIR performance.
Key Advantages
- Ultra-deep 50 % crossover at 411 nm - creates the widest warm passband in the CTO series with unusually early transition.
- Deep violet-blue notch (T < 5 % at 430-449 nm) - sharply removes the blue peak of LED and HMI sources while passing both violet and warm wavelengths.
- Peak of 95.8 % at 712 nm with NIR avg 93.9 % - delivers excellent red and NIR throughput.
- 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
- LED blue-peak suppression - specifically targets the 440 nm phosphor-converted LED peak, reducing blue hazard while preserving warm visible output.
- Circadian and human-centric lighting - removes the blue spectral peak that suppresses melatonin production, enabling healthier evening lighting.
- Stage and lighting design - creates a broad warm palette from green through NIR with a distinctive colour character unlike standard CTO.
- Machine vision spectral shaping - passes a wide warm band while rejecting the narrow blue peak, useful for LED-illuminated inspection systems.
- Photobiology and vision research - shapes broadband sources to study the effects of blue-peak removal on circadian rhythms and visual comfort.
Need prototypes in days or production volumes next quarter? CTO-048 filters can be coated, diced, and shipped to your exact specifications.
FAQ
CTO-048 FAQ
What is CTO-048 and what is it used for?
CTO-048 is a Color Temperature Orange Filter - Ultra-Deep Broadband Warm (T50% = 411 nm). CTO-048 is the most unique filter in the CTO series, with its 50 % crossover at 411 nm - deep in the violet region. This creates an ultra-wide warm passband that starts passing light from approximately 477 nm onward, with a deep blocking notch at 430-449 nm (T < 5 %). Common uses include LED blue-peak suppression, Circadian and human-centric lighting, Stage and lighting design, and Machine vision spectral shaping.
What are the key optical specs of CTO-048?
Key published specs for CTO-048 include Colour shift direction: Warming (5600 K → 3800 K); Mired shift: +67 Mired; Correction strength: 1/2 CTO; Average transmittance: ~55.5 % T (visible range); Peak transmittance: ~95.8 % T near 712 nm.
What applications is CTO-048 best suited for?
CTO-048 is commonly used for LED blue-peak suppression, Circadian and human-centric lighting, Stage and lighting design, and Machine vision spectral shaping. LED blue-peak suppression - specifically targets the 440 nm phosphor-converted LED peak, reducing blue hazard while preserving warm visible output.
Can CTO-048 be customized for size, substrate, or coating requirements?
KUPO lists the construction for CTO-048 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-048?
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
