Astronomik H-beta 1.25in Visual Filter (E28,5)

The Astronomik H-beta 1.25in 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.

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

• typ. transmission of better then 95% at the H-beta line
• complete blocking of all disturbing wavelengths
• Main operational use: Hydrogen Nebulae
• No moisture (humidity) sensitivity, no aging, and totally scratch-proof
• 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
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and aging 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

SKU: 8h0057