CTO-015 Color Correction Filter
¾-CTO glass filter: holds < 25 % T until 540 nm, rockets past 90 % by 630 nm, and rides a 92–95 % plateau through 780 nm—dropping daylight heads to a rich 3000 K tungsten tone without gel sag.
- Blue block: < 25 % T up to 540 nm
- Amber ramp: > 90 % T by 630 nm
- Red plateau: 92–95 % T through 630–780 nm
- CCT shift: −2500 – 2700 K (≈ ¾-CTO)
- Construction: Ion-assisted hard-oxide; 5–450 mm, 0.21–3.8 mm thick
- Custom options: AOI tuning, ripple smoothing, rush prototypes
Learn more
CTO-015 is KUPO’s strongest single-glass warm-up filter: a ¾-CTO correction that
drags a 5600 K daylight or cool-white LED fixture into true tungsten territory (~3000 K).
Transmission stays below 25 % right up to 540 nm, then rises steeply—breaking 90 % by
630 nm and holding a flat 92–95 % out to 780 nm. The steep roll-on removes harsh blue/cyan
while maximising red-orange output, giving cameras and eyes a rich, incandescent warmth
without the heat sag, fading, or spectral spikes of stacked plastic gels.
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, and can ship
prototypes in as little as two weeks.
Typical uses: tungsten-matching daylight panels on set, cosy amber washes for live
events, warm architectural accents in hospitality and retail, golden-hour flash modifiers,
and machine-vision stations where deep blue suppression boosts red-channel contrast.
Description
CTO-015 pushes daylight and cool-white LED sources firmly into the tungsten arena. Transmission stays below 25 % until roughly 540 nm, then climbs rapidly, breaking past 90 % by 630 nm and holding a flat 92 – 95 % all the way to 780 nm. The steep roll-on produces a strong amber hue—about a ¾-CTO correction—giving fixtures a rich, incandescent character while maximising red output and avoiding the heat-sag that plagues plastic gels.
Key advantages
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¾-CTO warmth – Shifts 5600 K daylight toward ~3000 K for seamless tungsten matching.
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High red efficiency – > 90 % T from 630 – 780 nm keeps lumen output high and skin-tones vibrant.
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Robust blue suppression – < 25 % T below 540 nm eliminates harsh blue glare from LED or HMI sources.
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All-glass durability – Hard oxide coatings resist heat, UV and abrasion far longer than polyester or polycarbonate gels.
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Custom sizing – Round, square or free-form blanks from 5 mm to 450 mm, 0.21 – 3.8 mm thick, on Borofloat®, soda-lime, D263 T or Corning Eagle XG glass.
Typical applications
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Film & TV lighting – Warm daylight panels or HMIs without stacking multiple gels.
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Stage & live events – Create cosy amber washes and key lights that stay bright show after show.
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Architectural accenting – Add inviting warmth to lobbies, restaurants and retail while blocking blue that can fade fabrics.
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Photography strobes – Give speed-lights or monolights a golden-hour tint for portrait and product work.
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Machine-vision – Boost red-channel contrast for inspections where blue light obscures defects.
Need a prototype in days or a production run next quarter? CTO-015 filters can be coated, diced and delivered to your exact spec—fast.
