LEE209 Neutral Density (ND) Filter
Neutral-density 0.4 OD glass: 37–40 % T across the whole visible band—Lee 209 effect with zero colour shift and rock-solid heat resistance.
- Blue end: ~40 % T @ 380 nm (colour-true)
- Red end: ~37 % T @ 780 nm (±2 % flatness)
- Optical density: 0.40 – 0.43 OD (≈ 1 ⅓-stop cut)
- Colour shift: < ±2 % across 400–700 nm
- Construction: Hard-oxide on glass; no polarisation, no glare
- Custom options: 5–450 mm, 0.21–3.8 mm thick, AOI tuning, rapid prototypes
Learn more
LEE209-glass is a spectrally flat neutral-density attenuator engineered to mirror the look of Lee’s
classic 209 gel while delivering the longevity of an all-glass, hard-oxide optic. Transmission
holds between 37 % and 40 % from violet through deep red, giving an optical density of about
0.4 OD (a 1 ⅓-stop reduction) with virtually no hue shift—whites stay white and colours stay
honest.
Unlike plastic gels that warp, bubble, or fade under heat, the ion-assisted coating shrugs
off high-power HMIs, COB LEDs, and tungsten halogen lamps, and resists solvents and scratches
during routine cleaning.
KUPO can supply the filter on 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.
Prototypes typically ship in about two weeks.
Typical uses: dimming stage or architectural fixtures without changing colour balance,
balancing film/broadcast sources to a common stop, exposure control for still and cine cameras,
safe attenuation of laser/LED beams on the bench, and intensity matching in scientific imaging
where spectral neutrality is critical.
Description
LEE209-glass is a true neutral-density attenuator designed to reproduce the look and feel of Lee’s 209 gel, but in a hard-coated, heat-proof optic. Transmission sits at ~40 % in the blue (380 nm) and gently declines to ~37 % by 780 nm, holding colour balance within ±2 % across the visible spectrum. The result is an ND of roughly 0.4 – 0.43 (a 1 ⅓-stop cut) that dims a beam without shifting its hue—ideal anywhere you need to tame intensity while keeping whites white and colours honest.
Key advantages
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Spectrally flat ND (~0.4 OD) – Uniform 37 – 40 % T from 400 – 700 nm for colour-faithful dimming.
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Gel-perfect match – Replicates Lee 209’s look, letting designers swap between gel and glass seamlessly.
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All-glass durability – Hard oxide coatings shrug off heat, UV and cleaning solvents that destroy plastics.
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No polarisation, no glare – Maintains beam quality and lamp characteristics unlike some film-based NDs.
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Custom sizes & substrates – Round, square or shaped blanks up 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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Stage & architectural lighting – Trim output of overly bright fixtures without gelling every show.
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Broadcast & film lamps – Balance daylight units to match tungsten or keep all sources on the same stop.
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Photography & cine cameras – Control exposure and depth-of-field when in-lens ND slots are unavailable.
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Laser & LED bench work – Safely attenuate beams for sensor testing or photodiode calibration.
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Scientific imaging systems – Achieve repeatable intensity reduction with zero spectral bias for fluorescence or colourimetry.
Ready for quick prototypes or high-volume production, LEE209-glass filters are shipped cut, edged and cleaned to your exact spec—fast.
