CTO-013 Color Correction Filter
½-CTO glass filter: < 10 % T below 530 nm, > 90 % at 580 nm, and 75-85 % across red—dropping daylight fixtures ~2100 K toward tungsten without gel hassles.
- Blue cut: < 10 % T from 385 – 530 nm (cold edge removed)
- Amber ramp: > 80 % T by 570 nm • peak > 90 % T @ 580 nm
- Red band: 75 – 85 % T through 600 – 670 nm • ~70 % T @ 780 nm
- CCT shift: −2100 K (≈ ½-CTO, 5600 K → 3500 K)
- Construction: Hard-oxide on glass; 5 – 450 mm, 0.21 – 3.8 mm thick
- Custom options: AOI tuning, ripple smoothing, rapid prototypes
Learn more
CTO-013 is the heaviest single-glass warm-up in KUPO’s line—about a ½-CTO correction.
It virtually eliminates blue-cyan (< 10 % T below 530 nm), then rockets past 80 % T by 570 nm
and peaks above 90 % T at 580 nm before gliding through the red (75-85 % T) and settling near 70 % T at
780 nm. A 5600 K daylight head lands close to 3500 K with rich tungsten-like ambience and minimal light loss.
KUPO coats Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG substrates cut to any outline—from
5 mm chips to 450 mm plates—in thicknesses of 0.21 – 3.8 mm. Prototypes ship in ~2 weeks.
Typical uses: warming daylight fixtures for film/broadcast, cosy amber stage washes,
museum or retail accent lighting, golden-hour strobe mods, and red-contrast machine-vision tasks
where deep blue suppression is key.
Description
CTO-013 is the heaviest of our single-glass warm-up filters—roughly a ½-CTO correction that drops a 5600 K daylight source to the neighbourhood of 3500 K. Blue–cyan energy is virtually eliminated (< 10 % T between 530 - 385 nm), then transmission rockets past 80 % by 570 nm, peaks above 90 % around 580 nm, and stays between 75 – 85 % through the heart of the red band before settling near 70 % at 780 nm. The result is a rich, tungsten-like ambience with excellent red efficiency and none of the plastic-gel heat issues.
Key advantages
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½-CTO colour shift – Delivers a strong, cinematic warmth ideal for matching tungsten or creating sunset looks.
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High red–orange throughput – > 80 % from 570 – 670 nm keeps fixtures bright and skin-tones lively.
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Deep blue suppression – < 10 % T between 530 - 385 nm kills the cold edge of white LEDs or HMIs.
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All-glass durability – Hard oxide coatings resist heat, UV and scratching far longer than polymer gels.
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Customisable sizes – Any shape from 5 mm to 450 mm, 0.21 – 3.8 mm thick, on Borofloat®, soda-lime, D263 T or Corning Eagle XG substrates.
Typical applications
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Film & broadcast – Warm daylight fixtures to blend seamlessly with practical tungsten on set.
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Stage lighting – Create cosy amber washes or key lights without sacrificing lumen output.
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Architectural & museum – Add inviting warmth to galleries and retail while protecting artefacts from UV.
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Strobe & flash modifiers – Give speed-lights a golden-hour tint for portrait and product work.
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Machine-vision & inspection – Enhance red-channel contrast where blue suppression improves defect detection.
Need prototypes next week or production volumes next quarter? CTO-013 filters can be coated, diced and shipped to your exact specification—fast.
