CTO-003 Color Correction Filter
¼-CTO glass filter: eases daylight fixtures ~700–900 K warmer with > 80 % red throughput and a smooth blue roll-off that keeps output high.
- Blue dip: ~43 % T @ 427 nm, climbs smoothly thereafter
- 50 % point: ≈ 530 nm (mid-slope transition)
- Red plateau: 80 % T @ 630 nm → 90 % T @ 710 nm
- CCT shift: −700 – 900 K (≈ ¼-CTO)
- Construction: Ion-assisted hard-oxide; 5 – 450 mm, 0.21 – 3.8 mm thick
- Custom options: Ripple flattening, AOI tuning, rapid prototypes
Learn more
CTO-003 gives a gentle amber tilt—about a ¼-CTO step—perfect when a full or half CTO would
sap too much output. Transmittance bottoms near 43 % at 427 nm, rises through ~60 % at 530 nm,
70 % at 570 nm, 80 % near 630 nm, and tops out around 90 % by 710 nm before tapering through the far red.
The smooth curve trims blue just enough to nudge 5600 K sources into the mid-4000 K range while preserving punch
and avoiding a cyan cast.
KUPO coats Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG glass cut to any outline—from
5 mm chips to 450 mm plates—in thicknesses of 0.21 – 3.8 mm, and can ship prototypes in roughly two weeks.
Typical uses: warming daylight panels for film sets, softening cool LED house lights on stage,
subtle flash modifiers, museum lighting needing a warmer tone without UV, and machine-vision tasks
that benefit from enhanced red contrast without large lumen loss.
Description
CTO-003 gives a gentle amber tilt—roughly a ¼-CTO step—to daylight or cool-white sources. Transmission bottoms near 43 % around 427 nm, then climbs steadily: about 60 % at 530 nm, 70 % at 570 nm, 80 % near 630 nm, and just over 90 % by 710 nm. The smooth slope trims enough blue to nudge a 5600 K fixture down to the mid-4000 K range while preserving most of its output and avoiding a heavy orange cast.
Key advantages
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Subtle ¼-CTO shift – Lowers CCT by roughly 700–900 K, great for blending daylight heads with warmer fills.
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High red throughput – > 80 % beyond 650 nm keeps brightness and skin tones intact.
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Even spectral curve – No harsh notches, so cameras see neutral colour without green spikes.
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Hard, heat-stable oxide coating – Handles high-power LEDs, HMIs, and follow-spots far beyond plastic-gel limits.
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Customisable blanks – Round, square, or free-form pieces from 5 mm to 450 mm, 0.21–3.8 mm thick, on Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG glass.
Typical applications
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Film & broadcast lighting – Warm daylight panels just enough to grade smoothly with tungsten practicals.
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Stage & architectural rigs – Soften cool LEDs for more inviting ambience without deep colour filters.
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Photography modifiers – Fine-tune flashes for mixed-light sets while keeping output high.
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Museum & retail displays – Add warmth to LED spotlights without introducing damaging UV.
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Machine-vision illumination – Boost red-channel contrast for inspecting organic materials or printed codes.
Need a prototype in days or production lots next quarter? CTO-003 filters can be coated, cut, and shipped to your exact specification—fast.
