Astronomik H-Beta Line Nebula Filter-1.25" w/12nm bandwidth

• Transmission of nearly 100% of the H-beta line
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  Complete blocking of all extraneous wavelengths
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  Main operational use: Hydrogen Nebulae
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  No moisture (humidity) sensitivity, no aging, and totally scratch-proof
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  Excellent carrier material - substrate is optically polished. The optical performance (resolution & contrast) of your telescope is not reduced in any way by the filter.
  Parfocal with other Astronomik filters
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  Glass thickness: 1mm
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  Diffraction limited, the filter will not reduce the optical performance of your telescope!
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  Astronomik filters are delivered in a high-quality, long lasting, filter box

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 f/4.5-f/6. The range of application extends from f/3.5 to f/15. Transmission losses and chromatic distortions, which arise with other filters, are only apparent with the Astronomik filters when extremely fast aperture ratios of f/3 and shorterer 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 is best used on telescopes with a diameter of 8 " (20cm) or larger. Smaller instruments do not gather enough light for meaningful and satisfying astronomical work with such a restrictive filter. 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 only a couple dozen 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.
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