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.
| 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" |
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) 2"
Optolong L-Quad Enhance (L-QEF) 2" mounted.
| Transmission at emission lines | >90% |
|---|---|
| Blocking depth | OD2–OD4 |
| Recommended skies | Bortle 1–7 |
Data sheet
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
