LEE299 Neutral Density (ND) Filter
Ultra-heavy ND glass: 1.5–3 % T (ND 1.6–1.8) from 400–780 nm—Lee 299 gel performance with 5–6⅔-stop cut and zero colour shift.
- Blue end: ≈ 1.5 % T @ 400 nm (colour-neutral)
- Red end: ≈ 3 % T @ 780 nm (± <2 % ripple)
- Optical density: 1.6 – 1.8 OD (≈ 5 – 6⅔-stop)
- Spectral flatness: < 2 % RGB variation 400–700 nm
- Construction: Hard-oxide on glass; 5–450 mm, 0.21–3.8 mm thick
- Custom options: AOI tuning, edge finishing, rush prototypes
Learn more
LEE299-glass is KUPO’s deepest neutral-density attenuator, matching the look of Lee’s
299 gel while offering the endurance of a hard-coated optic. Transmission holds between
1.5 % and 3 % across the 380 – 780 nm span—roughly 1.7 OD—delivering a dramatic 5- to
6 ⅔-stop cut with virtually no colour bias. The low-scatter dielectric stack rides on
polished borosilicate or fused-silica glass, shrugging off > 5 kW arc lamps, COB LEDs,
and routine solvent wipes. Reflective design dumps excess heat back toward the source,
protecting downstream optics and sensors.
KUPO supplies discs, squares, or free-form parts in sizes from 5 mm chips to 450 mm
plates and thicknesses of 0.21 – 3.8 mm, on Borofloat®, soda-lime, Schott D263 T,
or Corning Eagle XG glass. Prototypes ship in about two weeks.
Typical uses: camera exposure control under full sun, sensor-safe laser alignment,
daylight simulators in architectural models, saturation prevention in scientific imaging,
and theatrical effects requiring ultra-deep fades without colour cast.
Description
LEE 299 is an ultra-heavy neutral-density (ND) glass that knocks down visible light to just ≈ 1.5 % at the blue end (400 nm) and ≈ 3 % near 780 nm while staying impressively flat and colour-neutral across the spectrum. In exposure terms that’s roughly ND 1.6 – 1.8 (-5 – -6 ⅔ stops)—ideal when you need to tame searing sources without introducing a colour cast or spectral ripple.
Key advantages
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Ultra-heavy ND (ND 1.6 – 1.8) – 1.5-3 % transmission slashes intensity by 5-6 ⅔ stops for maximum light control.
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Colour-neutral response – < 2 % spectral ripple from 400-700 nm preserves white balance and skin tones.
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High damage threshold – all-dielectric stack on borosilicate or fused-silica substrates shrugs off > 5 kW arc lamps and high-power LEDs.
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Low thermal rise – reflective design dumps most heat back toward the source, protecting downstream optics.
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Made to order – round, square, or free-form parts from 5 mm to 450 mm, 0.21-3.8 mm thick, shipped quickly.
Typical applications
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Cinema & broadcast cameras – keep shutter speed and aperture creative under full sun without colour compromise.
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Laser & lamp alignment – protect sensors or eyes while you centre high-brightness beams.
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Architectural mock-ups & light boxes – balance zones in daylight simulators and scale models.
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Scientific imaging – prevent detector saturation in fluorescence or photometry rigs.
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Stage & themed attractions – create ghostly silhouettes or deep fades without shifting gel colour.
Need prototypes next week or a thousand blanks next quarter? We’ll coat, dice, and deliver LEE 299 ND glass to your exact specs—fast.
