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

  (10 Reviews)
✓ 2 year warranty


7x in stock shipped 1-2 working days

About this product

Model:  opt_l-pro_2
Part Number:  10202

Excellent choice for use as an LRGB Imaging Luminance Filter and Visual Light Pollution Filter. 

The L-Pro (L-Professional) filter improves the visibility of various deep-sky objects.

Selectively reduces transmission of wavelengths from light pollutants, including those produced by artificial lighting, including mercury vapour lamps, high & low-pressure sodium vapour lights and unwanted natural light caused by neutral oxygen emission in our atmosphere (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), and SII (672nm). So enhances contrast and detail for visual and photographic astronomy in areas with heavy light pollution. 

Unlike UHC and CLS light pollution filters, the L-Pro is a multi-bandpass filter so it offers better colour balance by maximising the transmission band.

The balanced transmission provides images with minimal colour cast of broadband emission objects such as galaxies, reflection nebulae and globular star clusters.

Optolong 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 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 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 minimises vignetting by maximising 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 (10 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Excellent filter
15 November 2023  | 

I've used this filter from bortle 9 zones and all through summer and it's just amazing how accessable it makes astrophotography. There are some issues with star halos that I'm not sure can be avoided. But I've found I can often process them out. Almost a necessity if imagine in light pollution (which is most of us these days)

Rating (max 5):  
Great filter let down by poor EOS-C Clip
17 August 2023  | 

Please note that I am reviewing the EOS-C clip version rather than any other type of fitting. I have rated this 3 stars because although the filter itself is worthy of 5 stars, the poor reliability of the EOS-C clip lets it down very badly. I have now purchased both the L-Pro (from FLO) and CLS-CCD (from a well know competitor) and in both cases the fit is very poor. In the case of the CLS-CCD, it just about stays in place if rotated through 180 degrees. The L-Pro drops out no matter how it is orientated in the camera body. I note from various astrophotography community sites that others have experienced thesame problem with this style of EOS-C clip. Others have not. There seems to be a significant amount of luck as to whether an individual filter will fit. In one YouTube video the presenter, using the same Canon camera body as myself, manages to fit 3 different Optolong EOS-C clips without any problem. I have contacted Optolong about this issue but received no reply from them. By using tiny pieces of sticky tape, I am able to hold the filters in place and make use them. However, this is not something one expects to be necessary when spending in excess of 150.
If you are considering one of these filters with the EOS-C clip fitting, be aware of the potential issue.

Rating (max 5):  
30 July 2023  | 

Great prompt service from FLO. Parcel was on my doorstep in Australia in 8 days. Clouds cleared for a few hours last night and the filter performed well. Very happy with product and service.

Rating (max 5):  
OPtolong L-Pro
29 June 2023  | 

This is an excellent filter.
I've used the EOS 600D clip version. So I know it's a very good light pollution killer. What makes it special is the transmission wavelength. It is designed so that it can remove the effects of LED street lighting. Making it easier to image from light polluted areas. I brought the 2 inch version for my ASI294MCPRO.

Rating (max 5):  
Optolong L-Pro Broadband filter
19 May 2023  | 

As normal for the UK I have not had the opportunity to use to the fullest extent due to our wonderful weather, but as many others have said it is a quality filter at a great price.

Rating (max 5):  
Optolong L-Pro
11 December 2022  | 

A superb filter for galaxies from my bortle 6. I use this with my Stella Mira 90mm 5mins subs and the results are fantastic. Thanks Alex and Flo for the great advice and help when buying a product.
Delivered in perfect condition in superb packaging from FLO as always.

Rating (max 5):  
Optolong L-pro
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
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
02 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
29 May 2021  | 

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


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