Optolong L-Quad Enhance (L-QEF) filter 2" The L-Quad Enhance (L-QEF) is a quad-bandpass light-pollution filter for colour cameras. It passes more than 90% at H-beta, OIII, H-alpha and SII while suppressing mercury and sodium lighting and natural skyglow, giving good colour balance on nebulae and galaxies. Optolong recommends it for Bortle 1–7 skies.
Manufacturer model: Optolong L-Quad Enhance (L-QEF) 2" · Specifications checked against manufacturer data on 2026-11-03
The L-Quad Enhance (L-QEF) is a quad-bandpass light-pollution filter for colour cameras. It passes more than 90% at H-beta, OIII, H-alpha and SII while suppressing mercury and sodium lighting and natural skyglow, giving good colour balance on nebulae and galaxies. Optolong recommends it for Bortle 1–7 skies.
Specifications
Format
2" mounted (M48 × 0.75)
Passbands
H-beta, OIII, H-alpha, SII (quad bandpass)
Transmission at emission lines
>90%
Substrate
Optical glass
Thickness
1.85 mm
Blocking range
300–1000 nm
Blocking depth
OD2–OD4
Recommended skies
Bortle 1–7
Thread
M48 × 0.75
Surface quality
60/40
Transmitted wavefront
λ/4 RMS
Parallelism
30"
Coating
Multi-layer anti-reflection coating on a non-cemented substrate, applied by ion-assisted deposition for durability and a stable centre wavelength with temperature.
Optolong L-Quad Enhance (L-QEF) filter 2" The L-Quad Enhance (L-QEF) is a quad-bandpass light-pollution filter for colour cameras. It passes more than 90% at H-beta, OIII, H-alpha and SII while suppressing mercury and sodium lighting and natural skyglow, giving good colour balance on nebulae and galaxies. Optolong recommends it for Bortle 1–7 skies.
Manufacturer model: Optolong L-Quad Enhance (L-QEF) 2" · Specifications checked against manufacturer data on 2026-11-03
