Optolong L-eXtreme Filter

SKU: lextreme-1.25

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  • Regular price $239.00

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Unlike the Optolong L-eNhance filter which is a tri-band (transmits Hb, Ha, and OIII), the L-eXtreme filter is dual band that passes Ha and OIII emission lines.

L-eXtreme is a two 7nm bandpass filter which can be used with one-shot color cameras like DSLR's (digital SLR), and monochrome CCD cameras, it is also more suited for fast systems. The convenience and cost effectiveness of this filter allows amateurs to image a rich emission nebulas, even in bright, light pollution skies. Optolong believes the design of L- eXtreme filter would be better choice for fast systems in competitive price. It isolates the H-Alpha, and Oxygen III nebula emission lines so that the contrast and signal-to-noise ratio between nebulae were maximized. For people who is living in very light polluted areas, or when the moon is out, the L-eXtreme will be a good filter.

The advantage of the L-eXtreme filter is that there is no transmission between the H-beta and OIII lines, as there is no nebula emission lines there. In this case, it isn't letting light pollution come through so that maximize nebulas signal and make the sky background darker while imaging. The L-eXtreme filter should better isolate the emission lines only and better protect from light pollution.

Which to Choose?

  • L-Pro provides the broadest spectrum and most natural color. Suitable for imaging nebula and galaxy targets.
  • UHC is not as broad spectrum, less natural color, but will block more stray light and skyglow than the L-Pro. Best suited to nebula targets, not broad spectrum targets like galaxies or clusters.
  • L-Enhance is a narrow tri-band filter. Best suited to capturing dim nebula targets. Will decrease brightness of surrounding stars, allowing for more faint detail. 
  • L-eXtreme is a dual-narrow-band filter providing the tightest spectrum in only H-Alpha and OIII. Suitable for deep sky imaging under light polluted skies, and delivering the richest nebula detail.

If you plan to use the filter to image a wide range of targets, the L-Pro is the most versatile. The L-eXtreme will provide the most faint detail on emission nebula, and the UHC is a budget option in the middle.






    O3 7nm+Ha 7nm

    Blocking range


    Blocking depth

    light pollution lines blocked >99.9%

    Surface quality


    Transmitted Wavefront RMS:





    • Plastic PP Case
    • Imported High Pressure EVA Case Lining
    • Silver Cardboard Box
    • High Density Sponge Carton Lining


    • Standard 1.25”
    • Standard 2”