Optolong 2" L-Quad Enhance Filter (L-QEF)

Description

2" Quad-Bandpass Light Pollution Suppression Filter

The Optolong L-Quad Enhance Filter (L-QEF) is a quad-bandpass light pollution suppression filter designed specifically for color astrophotography cameras. It allows you to capture deep-sky targets in stunning detail, even from suburban or moderately light-polluted skies, by blocking unwanted artificial light while preserving the natural glow of celestial emission lines. By suppressing the wavelengths emitted by mercury and sodium street lamps as well as the effects of natural skyglow, the L-QEF delivers images with enhanced contrast, color balance, and fine structural detail. Nebulae, galaxies, and star clusters appear more distinct and three-dimensional, while stars remain sharp and well-defined.

Wide Applications: From Milky Way to Deep Sky

The L-QEF is versatile enough for both wide-field astrophotography (such as capturing the Milky Way in summer or winter) and deep-sky imaging of emission nebulae, reflection nebulae, galaxies, and clusters. Thanks to its quad-bandpass design, it maximizes signal from key emission lines — H-Beta, OIII, H-Alpha, and SII — while maintaining an excellent broadband color balance, something rarely achieved with other light pollution filters.

Superior Light Pollution Suppression

Streetlights and urban glow no longer need to ruin your astrophotography sessions. The L-QEF selectively blocks the wavelengths associated with mercury and sodium vapor lamps, while allowing essential emission lines such as H-Beta, OIII, H-Alpha, and SII to pass through with over 90% transmittance. This makes it possible to capture nebulae, galaxies, star clusters, and even the Milky Way against a darkened sky background.

Designed for Color Cameras

Optimized for one-shot color (OSC) cameras, the L-Quad Enhance Filter enhances image saturation, color fidelity, and sharpness. By cutting IR wavelengths up to 1000 nm, it also reduces unwanted infrared noise, leading to cleaner and more precise astrophotography results.

Key Features

• Suppresses light pollution: Effectively blocks mercury and sodium lamp emissions with minimal color cast.
• High transmission: Over 90% transmittance of H-Beta, OIII, H-Alpha, and SII emission lines.
• Near-IR cutoff: Cuts infrared light up to 1000 nm, reducing IR noise and improving clarity.
• High contrast & color fidelity: Provides richer details and more natural colors in nebulae, galaxies, and clusters.
• Optimized for OSC cameras: Designed to work perfectly with one-shot color cameras, balancing broadband targets and emission line objects.

Advanced Coating Technology

Optolong applies Ion-Assisted Deposition (IAD) coatings to ensure durability, resistance to scratches, and temperature stability of the filter’s central wavelength. Multi-layer anti-reflection coatings reduce unwanted reflections and enhance light transmission, while a planetary rotation system guarantees precise and uniform coating application. This results in a filter with exceptional longevity and optical performance.

Technical Specifications

• Substrate: Optical glass
• Thickness: 1.85 mm
• Filter Type: Quad-bandpass
• Blocking Range: 300–1000 nm
• Blocking Depth: OD2–OD4
• Surface Quality: 60/40
• Transmitted Wavefront RMS: λ/4
• Parallelism: 30s
• Filter Size: 2" (50.8 mm), round, threaded (M48×0.75)
• Cutoff: Near-IR up to 1000 nm