Optolong L-eXtreme


  • 1.25″ Mounted
  • 2″ Mounted (48mm thread)

Spectral Transmission

Yellow line is published transmission. Color fill is my independent verification with the filter I tested.

Physical Characteristics of 2″ Filter

  • Filter mount thickness: above threads: 4.92mm; including threads: 6.78mm
  • 48mm threads with 0.75mm spacing
  • Minimal knurling only on top
  • Dual bandpass narrowband filter
  • Inner retaining ring does have notches for easy filter disassembly with a spanner
  • Width of the glass filter without the filter mount is 45.94mm

Real World Tests

Bortle 8, Stock Canon T7, 464mm f.l., f/5.4, ISO3200, 36 min. integration (6*6″). Open full-size image in new tab.
Bortle 8, Full Spectrum Modified Canon 60D, 464mm f.l., f/5.4, ISO3200, 36 min. integration (6*6″). Open full-size image in new tab.

Comparisons to No Filter

Before Image After Image
Stock Canon T7 - No filter vs. Optolong L-eXtreme

Before Image After Image
Full Spectrum Canon 60D - No filter vs. Optolong L-eXtreme

Reader Rating48 Votes
7nm bandpasses provide good contrast and tight stars
Excellent light pollution blocker
Faint halos on very bright stars created by filter
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  1. Hi i wnat to know if there is best filter under 250$. I live at sky bortle 8 or 9. The first product I’m considering is l extreme and i want is there any better narrowband filter

    1. Hello, I would suggest getting a dual-narrowband filter that is in your price range. These are ideal for blocking light pollution like you have with Bortle 8/9. Lately, I have found the Svbony SV220 is a very good value and similar (if not slightly) better performance than the L-eXtreme. They both have dual 7nm bandpasses on Ha and OIII. Keep in mind these types of filters are only appropriate for emission nebulae. It will be counter-productive to use them on reflection nebulae, star clusters, and other broadband objects.

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Final Score