CTO-034 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: ~45.5 % T (visible range)
- Peak transmittance: ~92.6 % T near 685 nm
- Minimum transmittance: ~2.6 % T near 445 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-034 delivers a +131 Mired shift to move 5600 K light toward 3200 K. Its smooth spectral slope creates a natural warming effect, with about 45.5 % 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-034 is a strong red longpass CTO filter with its 50 % crossover at 645 nm. Virtually the entire visible spectrum below red is suppressed: blue averages 14.1 %, green 12.5 %, and yellow 13.9 %. Only the red band breaks through, rising to an average of 66.9 % before the NIR band reaches 90.8 %, peaking at 92.6 % at 685 nm. A notable violet shoulder at 380 nm (73.3 %) adds spectral complexity but does not significantly affect the overall deep-red character. The filter functions effectively as a red-NIR longpass with a steep cut-on.
Key Advantages
- 50 % crossover at 645 nm - provides a steep-edged red longpass with strong rejection of all shorter visible wavelengths.
- NIR throughput averaging 90.8 % - delivers excellent efficiency in the 700-800 nm band for combined red-NIR applications.
- Deep visible suppression (blue-green-yellow avg < 15 %) - approaches dedicated red-longpass performance from a CTO architecture.
- 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 - creates deep, saturated red washes with very little colour contamination from shorter wavelengths.
- Darkroom and safelight applications - passes only red and NIR, providing safe working illumination for photosensitive materials.
- Machine vision red-channel isolation - functions as a red-NIR longpass for defect detection, product sorting, and barcode reading under red illumination.
- Biomedical and fluorescence imaging - passes deep-red and NIR fluorophore emissions (Cy5, Alexa Fluor 647) while blocking shorter excitation wavelengths.
- Horticultural lighting - isolates the deep red and far-red bands important for phytochrome-mediated plant responses.
Need prototypes in days or production volumes next quarter? CTO-034 filters can be coated, diced, and shipped to your exact specifications.
FAQ
CTO-034 FAQ
What is CTO-034 and what is it used for?
CTO-034 is a Color Temperature Orange Filter - Strong Red Longpass (T50 % = 645 nm). CTO-034 is a strong red longpass CTO filter with its 50 % crossover at 645 nm. Virtually the entire visible spectrum below red is suppressed: blue averages 14.1 %, green 12.5 %, and yellow 13.9 %. Common uses include Stage and entertainment lighting, Darkroom and safelight applications, Machine vision red-channel isolation, and Biomedical and fluorescence imaging.
What are the key optical specs of CTO-034?
Key published specs for CTO-034 include Colour shift direction: Warming (5600 K → 3200 K); Mired shift: +131 Mired; Correction strength: Full CTO; Average transmittance: ~45.5 % T (visible range); Peak transmittance: ~92.6 % T near 685 nm.
What applications is CTO-034 best suited for?
CTO-034 is commonly used for Stage and entertainment lighting, Darkroom and safelight applications, Machine vision red-channel isolation, and Biomedical and fluorescence imaging. Stage and entertainment lighting - creates deep, saturated red washes with very little colour contamination from shorter wavelengths.
Can CTO-034 be customized for size, substrate, or coating requirements?
KUPO lists the construction for CTO-034 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-034?
The ion-assisted hard-oxide coating is built for repeated handling, heat, and cleaning.
