Optolong L-Pro Light Pollution Broadband Filter
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Optolong L-Pro Light Pollution Broadband Filter

  (4 Reviews)
✓ 2 year warranty


5x in stock shipped 1-2 working days

About this product

Model:  opt_l-pro_1.25
Part Number:  10201

Excellent choice for an LRGB Imaging Luminance Filter and a Visual Light Pollution Filter

The L-Pro (L-Professional) filter is designed to improve the visibility of various deep sky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapour lamps, both high & low pressure sodium vapour lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

The filter has high transmission in the main nebula emission lines at OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha (656nm) as well as SII (672nm), the filter is suitable for enhancing the contrast and details for both visual and photographic purposes at sub-rural area with heavy light pollution. 

Unlike UHC and CLS light pollution filters, the L-Pro is a multi-bandpass filter which offers better colour balance by maximising the transmission band. The balanced transmission allows astro images to be taken with minimal colour cast to broadband emission objects such as galaxies, reflection nebulae and globular star clusters. L-Pro is the best choice for light pollution suppression.

IMPORTANT: Filters manufactured by Optolong are NOT designed for observing or photographing the Sun. DO NOT use Optolong filters to observe or photograph the Sun. If you do it will result in permanent eye damage! 


  • High transmission of main nebula emission lines (i.e. H-alpha 656nm, OIII 496nm and 500nm, SII 672nm and H-beta 486nm
  • Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm)
  • Suitable for visual observation and astrophotography
  • Effective UV / IR Suppression - Suitable for 'L' / Luminance Imaging Use
  • Narrower pass-band than CLS filter - Better suited for areas of higher light pollution 
  • Better colour balance for OSC imaging
  • 1.25" or 2" Mounted Sizes, EOS-C, EOS-FF and Nikon-FF Clip filters.
  • Supplied in a protective plastic case with EVA foam lining
  • 1mm (Clip Filters) or 2mm (1.25" / 2") Thick Schott Glass
  • Fine-optically polished on both sides - ensures accurate λ/4 wavefront and <30 seconds parallelism over the both surfaces

Transmission Chart

Red Line - Represents the transmission curve of the L-Pro Filter.

Green Line - The Major Emission Lines of Nebulae: H-α (656.3nm), H-β (486.1nm), OIII (495.9nm) and OIII (500.7nm)

Orange Line - The Major Emission Lines of Artificial Light Pollution: Hg / Mercury (435.8nm, 546.1nm, 577nm and 578.1nm), Na / Sodium (598nm, 589.6nm, 615.4nm and 616.1nm)

Technical Data

  • Schott substrate material
  • Thickness 2.0 mm (1.25”/2”)
  • Thickness 1.0 mm (Clip series)
  • Surface Quality: 60/40 (Refer to MIL-O-13830)
  • Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces
  • High transmission of main nebula emission lines (i.e. H-alpha 656nm, OIII 496nm and 500nm, SII 672nm and H-beta 486nm
  • Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm). Transmission of 0.1% is equivalent to OD3 (Optical Density), and a high optical density value indicates very low transmission, and low optical density indicates high transmission.

Coating Parameter

  • Multi-layers anti-reflection coating
  • Non-cementing optical substrate coating
  • Electron-beam gun evaporation with 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

Filter Cell

  • Ultra-thin filter cell minimise vignetting by maximise possible clear aperture (clear aperture is 26mm for 1.25”; 45mm for 2”)
  • Aerometal Material | Precise CNC Machining | Sand Blasting Process | Black Anodised Finish | Extinction Treatment to Prevent Reflection | Laser Engraving No Fading

Comparison Images

M42 / Orion Nebula

Summer Milky Way

Customer reviews

Average Rating (4 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Optolong L-pro
Tuesday, 29 November 2022  | 

Well packaged and arrived the next day. Not had chance to use it yet, but cannot fault the service from FLO

Rating (max 5):  
Money well spent
Wednesday, 21 September 2022  | 

Not had the weather yet to fully test on my new rig due to mount issues. But using another telescope and mount, first impressions look very promising. Fast delivery and service as usual from FLO.

Rating (max 5):  
Optolong L-Pro Filter
Wednesday, 2 June 2021  | 

I've just purchased the 2" version for my Evostar 72ED setup after using the 1.25" version fitted to an um-modified Canon 1000D on a Celestron 6SE. Quite frankly the results are astounding from my light polluted patio when compared to the same target without a filter. It really is worth the extra cost.

Rating (max 5):  
Optolong L-Pro Light
Saturday, 29 May 2021  | 

Haven't had a chance to use, this is just to say had delivery within 24 hours 👍


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