Skip to product information
1 of 2


Optolong L-Pro Filter

Optolong L-Pro Filter

Regular price $11,499.00 USD
Regular price Sale price $11,499.00 USD
Sale Sold out
Warning: As a critical safety reminder, the Optolong L-Pro filter is not intended for solar observation. It should NEVER be used to observe the sun directly, as it can result in irreversible blindness.  EDISLA does not assume responsibility for any incidents that may occur due to improper usage.
  • Optolong L-Pro filter is perfect for astrophotographers fighting light pollution
  • Best used for imaging most emission nebulae, reflection nebulae, and dark nebulae
  • Suitable for both visual photographic observations
  • Effective in suppressing light pollution sources 

Introducing the Optolong L-Pro Filter:

The Optolong L-Pro (L-Professional) filter is meticulously engineered to enhance the visibility of various deep-sky objects by selectively reducing the transmission of light pollutants, including those originating from artificial light sources such as mercury vapor lamps, high and low-pressure sodium vapor lights, as well as natural light caused by neutral oxygen emission (skyglow) in our atmosphere. Additionally, it offers excellent transparency in key nebula emission lines, including OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha (656nm), and SII (672nm). This makes the filter highly effective for enhancing contrast and capturing details for both visual observation and astrophotography in areas with heavy light pollution.

Key Features:

  • The Optolong L-Pro is a multi-bandpass filter designed to achieve superior color balance by maximizing the transmission band. Its balanced transmission allows for astrophotos with minimal color casting when capturing broadband emission objects such as galaxies, reflection nebulae, and globular star clusters. It is particularly well-suited for light pollution suppression.

L-Pro Introduction: The Optolong L-Pro filter is aimed at improving the visibility of various deep-sky objects by selectively reducing the impact of light pollution. It efficiently filters out wavelengths associated with artificial light sources and unwanted natural atmospheric light. Combined with its transparency in key nebula emission lines, this filter enhances contrast and details for both visual and photographic purposes, particularly in suburban areas with substantial light pollution.

Main Use and Performance:

  • Suitable for visual observation and astrophotography.
  • The L-Pro filter exhibits a minimal reduction in transmission against continuous spectrum celestial objects, making it highly effective in suppressing light pollution when imaging galaxies, reflection nebulae, globular star clusters, and for visual star observations.
  • It is suitable for "L" image capture with CCDs.

Technical Data:

  • Substrate: Optical glass of fine material
  • Spectrum: 380-750nm
  • Surface Quality: 60/40 (Compliant with MIL-O-13830)
  • Precision optical polishing ensures an accurate 1/4 wavefront and < 30 seconds of parallelism over both surfaces.
  • High transmission in major nebula emission lines, including H-alpha (656nm), OIII (496nm and 500nm), SII (672nm), and H-beta (486nm).
  • Precision off-band blocking of major artificial light pollution emission lines, such as Na (589nm), Hg (435nm and 578nm).


  • Optolong L-Pro filter is available in various configurations:
    • 1.25" (1 1/4" mounted) and 2" mounted for eyepiece use.
    • Round 77mm and 82mm, designed to screw onto the objective lens.
    • SLR camera clip filters for EOS-C, EOS-FF, NK-FF, Sony-FF.

Coating Technology: The Optolong L-Pro Filter employs advanced coating technologies to ensure durability and optical performance, including multi-layer anti-reflection coating and non-cementing optical substrate coating. It adopts precision coating based on Ion-assisted deposition coating technology for scratch resistance and temperature stability. A planetary rotation system is utilized during the coating process to ensure precision and uniformity of coatings, resulting in high transmission in the pass-band and optimal optical density in the off-band.

    Packaging: The filter is thoughtfully packaged for protection:

    • Outer Box: Silver box
    • Plastic Box: Made of PP material
    • Lining: Features imported high-pressure white EVA material.

    In summary, the Optolong L-Pro Filter is an invaluable tool for astronomers and astrophotographers, tailored to enhance observations and imaging in light-polluted areas. Safety warnings must be heeded diligently, particularly regarding solar observations, to prevent potential eye damage.

    Interpreting the Chart: The provided chart offers insights into the filter's performance characteristics:

    • The horizontal axis represents the wavelength in nanometers (nm).
    • The vertical axis illustrates transmission percentages (%).
    • The WHITE line represents the filter's transmission, while artificial lines are depicted in YELLOW. The H-Beta line is shown in BLUE, the OIII line in GREEN, and the H-Alpha line in RED.

    View full details