Astronomik H-beta Filter

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About this product

The Astronomik H-beta is a filter for visual observation, in particular with instruments of larger aperture. 

It lets the light of the H-beta emission line pass nearly unhindered and blocks the remaining spectral range to the extent that the eye is dark adapted. By the use of the Astronomik H-beta filter, the contrast is increased so strongly, that even the observation of the Horse Head Nebulae with telescopes of 10" - 12" reaches the realm of the possible.

Main use

The optimal aperture ratio for the use of the filter is 1:4,5 to 1:6. The range of application extends from 1:3.5 to 1:15. Transmission losses and chromatic distortions, which arise with other filters, are only apparent with the Astronomik filters when extremely fast aperture ratios of 1:3 and higher are used.

The Astronomik H-beta filter will allow you to view large objects, in the whole field of view of the eyepiece, even when using wide-angle eyepieces - not only in the center of the eyepiece.

This filter should be used on telescopes with a diameter of 8 " (20cm) or larger. Smaller instruments do not gather enough light for meaningful and satisfying astronomical work.

Due to the high optical quality of the Astronomik H-beta filter substrate you will see the same needle-sharp stars as you would from your regular telescope.

Other uses

• In the whole sky, there are few objects that benefit from the use of this filter in visual observation. On the other hand h-beta filters often decide about seeing or not seeing an object. Without a filter the eye is hardly able to discover the low contrasts of H-alpha regions.
• With EOS Clip Filter even in extreme light polluted areas photography with DSLR cameras becomes possible.

Transmission Chart

• The horizontal axis is the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous "H-Alpha" emission line of hydrogen.
• The transmission in % is plotted on the vertical axis.
• The blue line shows the transmission of the filter.
• The most important emission lines from nebulas are shown in orange. The most important lines are from ionised Hydrogen (H-alpha and H-beta) and double ionised oxygen (OIII).

The major emission lines of artificial light pollution:
| Hg 435,8nm | Hg 546,1nm | Hg 577,0nm | Hg 578,1nm |
| Na 589,0nm | Na 589,6nm | Na 615,4nm | Na 616,1nm |

The major emission lines of nebulas:
H-β 486,1nm | OIII 495,9nm | OIII 500,7nm | H-α 656,3nm

Suitability

• Visual observation (dark skies): Very good, but only suitable for a few objects
• Visual observation (urban skies): Unsuitable
• Film photography: It depends, very long exposure time
• CCD photography: Good, when used with an additional IR-block-filter
• DSLR photography (original): Very good, but only suitable for a few objects
• DSLR photography (astro modified): Very good, but only suitable for a few objects
• DSLR photography (MC modified): Good, when used with an additional IR-block-filter
• Webcam / Video (Planets): Unsuitable
• Webcam / Video (Deep Sky): Unsuitable

​Technical Data

• Transmission of nearly 100% of the H-beta line
• Complete blocking of all disturbing wavelengths
• Main operational use: Hydrogen Nebulae
• Scratch-resistant!
• Excellent carrier material. The optical performance of your telescope is not reduced by the filter in any way.
• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and ageing effects
• Diffraction limited, the filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long lasting, filter box

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