L-QEF Introduction

L-Quad Enhance Filter (L-QEF) is a quad bandpass light pollution suppression filter for colour cameras. It effectively suppresses the transmission of light pollution wavelengths, especially light pollution generated by artificial lighting (including mercury and sodium lamps), as well as the effects of natural skylight-induced effects on the shot, thus effectively enhancing the contrast and details of the celestial bodies, and making the objects more distinct and stereoscopic. This filter provides better color balance while improving rejection of light pollution. L-QEF can be used for both wide field astrophotography, such as the Milky Way in Summer and Winter, and deep sky objects such as nebulae, galaxies, star clusters, and so forth; It allows you to save a lot of time during the shooting process and get better results at the same time. The design of quad bandpass maximises the colour balance of nebulae, galaxies and other broadband spectral targets.

Key Highlights

• Cuts out light pollution from mercury and sodium lamps and produces a nice broadband image with minimal colour cast;
• High signal-to-noise ratio (SNR);
• Near IR cut-off to 1000nm, reducing the effects of IR noise;
• L-QEF has more than 90% transmittance of the nebula emission lines at H-Beta/OIII/H-Alpha/SII, with cut-off depth from OD2 to OD4, thus providing a significant increase in rejection to light pollution. L-QEF is good for night sky from Bortel 1 to Bortel 7 levels; (Bortel 8, Bortel 9 environment shall not be recommended, kindly chose Optolong other narrow-band filters, 3nm, 7nm type of filters are available.);
• Suitable for wide range of deep sky targets: it covers most nebulae, galaxies, star clusters, reflected and emitted line signals astronomical objects with higher contrast and rich details while maintaining excellent colour balance. L-QEF is superior to other filters of the same type.

Coating Technology

• Multi-layers anti-reflection coating
• Non-cementing optical substrate coating
• Optolong filter adopts precision coating based on Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change.
• Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.

Spectrum and Characteristic

Substrate: Optical glass
Thickness: 1.85mm
FWHM:  Quad bandpass filter
Blocking range: 300-1000nm
Blocking depth: OD2-OD4
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism: 30s

*   The transmission curve above is for reference and illustration purpose only

How to read the chart?

▲The horizontal axis is the Wavelength in Nanometers(nm).

▲The vertical axis is transmission in %.

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