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Optolong Hydrogen Beta Narrowband (12nm) Filter - 2"

5.0 (1 Reviews) Read Reviews Write Review
Brand Optolong
Part Number Q1HB012404Y

Product Info

Manufacturer Description

A. About Optolong's H-beta (12nm) FIlter

The Optolong H-beta (Hydrogen-Beta) narrowband filter is designed to improve the visibility of various deep sky objects. It does this by:

  • Selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lighting (including mercury vapor lamps, both high & low pressure sodium vapor lights, and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow)).
  • Allowing 12nm bandwidth of light centered on a wavelength of 486nm to pass through.

B. Main Uses and Performance

  • Use with a large aperture telescope under clear and dark viewing conditions with good seeing.
  • Suitable for viewing the faint and elusive Horsehead Nebula and California Nebula.

C. Spectral Curve Transmission Characteristics

  • 90% transmission at H-beta line 486nm
  • 0.1% transmission of major transmission lines of artificial light pollution:
    • Hg (Mercury) at 435.8nm, 546.1nm, 577nm, and 578.1nm.
    • Na (Sodium) at 598nm, 589.6nm, 615.4nm, and 616.1nm.

D. Technical Specifications

  • Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
  • 2mm thick Schott B270 optical glass substrate material.
  • Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).

E. Optical Coating Specifications

  • Multi layer anti-reflection coated.
  • 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) so that there is no deviation due to temperature changes during use.
  • Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
  • Every single filter is tested and passed by Optolong before shipping to dealers.

F. Other

  • 2" astronomy filter with standard M48x0.75 male filter thread (no female thread, so it cannot be stacked with other filters).
  • Ultra-thin filter cell to minimize vignetting; clear optical aperture of 45mm.
  • Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
  • High quality protective plastic storage case.

WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.


5.0 (Based on 1 Reviews) 100% of reviewers recommended this product.
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    1. AstroGuy1

      AstroGuy1 New Member

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      User Notes:
      Review by Chris from NC
      Jan 16, 2017

      5.0 Exceeded my expectations




      Test conditions: 10 inch dobsonian under Bortle 4 skies and 3 to 5 millimeter exit pupils made Horsehead, California and Cocoon Nebulas stand out from the background so that I could just detect them. I had been looking for these nebulae for years without success. This filter made all the difference. This is my first h-Beta filter. I tried a two millimeter exit pupil but it was too small and couldn't see as much. Filter threaded very smoothly into my Baader and TeleVue eyepieces. Very high quality construction. The filter body is not as tall as other filters so an additional filter cannot be stacked onto it.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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