Astronomy Specialist


$289.00 AUD
SKU: OP-13801


  • 25 nm
  • 11 nm



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 7 reviews
Paul Lloyd
A very handy, well made filter for emission targets

I've been using this filter for around 6 months, now, and have found that it is a very useful tool in my a.p. armoury. It is well made: the filter is solidly clamped in its holder, the holder ring is nicely narrow so that it is unlikely to be a problem mounting it in a filter wheel, and the loss of light transmission is not too much to concern most people. What I have found useful, though, is that it cuts the effects of Moon-glow by a good amount, helping to increase image contrast on those times when clear skies and target availability without Moon are limited. In addition, emission targets appear nicely sharp - sharper than unfiltered images of the same target. As I live in a Bortle 3-4 area, artificial light pollution is not a serious issue for me, so I cannot offer comments on its efficacy in this regard.

This is a filter for emission targets, not for general targets like star clusters and galaxies. And finally, is it a dual-band or a tri-band filter? It passes two bands of light, one for H-alpha, but the other is broader and passes both H-beta and O-III emissions. I'll leave it for those more knowledgeable than me to argue whether the definition should describe the bands of the filter, or the bands passed by the filter!

John Flaherty
Best filter for my situation

Was advised to look into purchasing this filter by a friend who has been involved with Astrophotography for a number of years, best advice I’ve been given as a newbie to this art form. Living in an urban area of Townsville Qld has me in a very light polluted suburb, but the filter takes away a lot of the pain shouting the night sky from my backyard! It’s a must have part of your kit to have available to you to achieve good results!

George Syrganidis
Great results!

Fantastic product, really awesome when you don't have much time to spend on an object and/or have moonlight present.

Graham hooker
Just 8.5 hours of data

Well have had the OPTOLONG L-eNhance FILTER for 35 days and only managed to get 8.5 hours of data. seeing was only 3 at a bortal 5 site. Tarantula Nebula was 4 hour, Helix Nebula was 4 and the Horses Head just 30 minutes. Scope is the SHARPSTAR 94EDPH APO TRIPLET F/5.5+Flattener reducer, ASI 183 MC Pro camera. Mount is a HEQ5 pro, ZWO Focuser and ASI120mm guid camera. Exposures where all 180 second Gain 120 and offset 15.
From the results so far the filter does pull out the extra detail in a pollute sky, I cant wait for the skies to improve so that I can retry all my old targets and see the improvement. I love the results obtained to date


Finally got this into place (2" version) and the quality of images are crazy good! Ever light across the image, no more light pollution in the corners, stronger nebula, sharper stars. Love it.



From $289.00 AUD


  • 1.25"
  • 2"

Optical design

Image circle

Focal ratio


Focal length

Optical thickness



Colour or Mono

Pixel size

Sensor dimensions


Sensor diagonal

Quantum efficiency

Read noise

Fullwell capacity

Bit depth


Camera backfocus

Filter size

1.25", 2"

Filter size

1.25", 2"

Bandpass (FWHM)

25 nm, 11 nm

Bandpass (FWHM)

25 nm, 11 nm

Glass thickness

2 mm

Mount type

Payload capacity

Latitude range

Dovetail saddle

Slew speed


Periodic error correction

Counterweight shaft

Azimuth adjustment range

Internal diameter

Illuminated diameter

Compatible telescope external diameter





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