OPTOLONG L-QUAD ENHANCE FILTER

The new Optolong L-Quad Enhance (L-QEF) is a quad-broadband astrophotography filter designed to drastically reduce the effect of light pollution under urban skies. Like the popular L-Pro filter, the L-QEF effectively blocks out the main sources of urban light pollution such as mercury and sodium streetlights while isolating deep sky objects. 

The L-QEF's quad bandpasses are engineered to retain a natural colour balance of nebulae, galaxies and broadband targets while maximizing contrast and faint details. With transmittance greater than 90% for the main nebula emission lines of H-Beta, OIII, H-Alpha & SII and a steep cut-off between OD2 - OD4, the L-QEF significantly decreases the impact of light pollution.

The L-QEF works best for locations in Bortle 1 - 7. For areas in Bortle 8 - 9, we recommend the L-eXtreme or L-Ultimate filters instead.

• The L-QEF blocks the artificial light from mercury vapour lamps, both high and low pressure sodium vapour lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

• Maximum transmission of the main nebula emission lines at OIII (500nm) and H-alpha (656nm).

• Cuts of near-IR to 1000nm, reducing the effects of IR noise.

• Ideal for urban areas with moderate - high light pollution.

• It incorporates an IR/UV-Cut filter that is necessary in astrophotography, especially for astronomy cameras that are sensitive to the infrared radiation.

• Ultra-thin filter cell to maximise the compatibility with most filter wheels.

• Multi-layers anti-reflection coating.

• Cell in Aerometal Material, CNC machined, sand blasted, black anodized and laser engraved.

• Plastic PP Case, high pressure EVA Case Lining.

Light pollution filters do not eliminate the effects of light pollution or increase the object’s brightness. It does increase the contrast between nebulae and night sky. 

The interferential coating is deposited on the substrate using electron-beam gun evaporation with Ion-assisted deposition coating technology. This increases the filter durability and resistance to scratching, as well as stability on CWL (central wavelength) and no deviation affected by temperature changes. The planetary rotation system offers precision and homogeneity of coatings ensuring high transmission of pass-band and high optical density off-band.

WARNING: Optolong filters are not designed for sun observations. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTERS. You could become BLIND if you fail to observe the warning.