Astronomy Specialist



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The Optolong L-eNhance filter is a light pollution tri-band filter designed to drastically reduce the effect of light pollution. Its three passing bands isolate the nebulae emissions in H-Alpha (red) and H-beta, OIII (green-blue).  This filter is designed for DSLR's and colour cameras under urban skies. It works as a combined H-Alpha and OIII / H-Beta narrowband filter so photos will appear highly contrasted without the necessity to use a monochrome camera and separate filters.

  • It 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 (496nm and 500nm), H-beta (486nm) and H-alpha (656nm).
  • Three transmission bands - ~25nm for OIII & H-beta, ~11nm for H-alpha.
  • Ideal for urban areas with 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.

Optolong l-enhance

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 of the 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.


Passing band Tri-band band H-Alpha (red) and H-beta, OIII (green-blue)
Glass thickness

2.0 mm (for 1.25" and 2" filters) ; 1 mm (clip series)

Optical flatness

1/4 λ (wavefront)

Band-pass transmission 90% across major nebulae bandpass
Coating Fully multi-coated
Surface quality
60/40 (in accordance with US military watch MIL-O-13830)
Parallelism 30"
Glass type
Schott monolithic optical substrate (non glued)
Available sizes 1.25", 2"


Optolong filter box

Horsehead Nebula - L-eNhance filter, SkyWatcher 200/800 reflector, ZWO ASI 294 Camera. Taken by Luca Fornaciari

Soul Nebula - L-eNhance filter, SkyWatcher Evostar 72Ed, QHY183C Camera. Taken by Luca Fornaciari

Elephant's Trunk Nebula - L-eNhance filter, SkyWatcher 200/800 Photograph, ZWO EAF Focuser. Taken by Luca Fornaciari

Customer Reviews

Based on 2 reviews
Barry Campbell
L-enhanced Emission Nebula Filter for Fast F2.8 Telescope and OSC Camera

As I have a Fast Sharpstar 150 HNT F2.8 telscope I needed a OSC filter for capturing Emission nebula and not shifting the wavelength out of range. The OPTOLONG L-enhanced Filter allows those emission nebular wavelengths through yet diminishes the light pollution from City Sky glow I have to the North and South.
IC2498 Running Chicken Nebula 12-08-21.
Clear sky and decided on IC24848 again using new L-Enhanced Filter this time but was sinking toward the South Sky Glow of Sydney from 36 deg to 18 deg.
60*180sec subs.
Sharpstar 150HNT F2.8, ASI294MC Pro, OptolongL-Enhanced Filter.
SkyWatcher AZ-EQ6 mount. EQMod.
Orion 50mm Guide scope with ASI120MC-S camera,
ASIAir Pro Control,ZWO EAF and Filterwheel.
Dew heater as heavy dew

Ulf Garbe
first images with l-enhance

I bought the l-enhance a week ago and had the chance of two nights taking images with Sharpstar 76 and Celestron SCT 9.25 (at full moon) on a Skywatcher AZ EQ6-R mount with QHY OAG and ZWO 294mc. I love the results and found it a great alternative to a costly upgrade with a camera (monochrome) with filter wheel and narrowband filter. I am not an expert with 1.5 years of experience now and I use Pixinsight for stacking and processing only. The filter makes a big difference with lots of light pollution in the Sydney/ Liverpool area.

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