Filter Astronomik H-? in the frame 1.25 "/ 31.7 mm.
Astronomic H-beta filter is a filter designed for visual observations, in particular instruments with a large aperture, hydrogen nebulae. The filter allows the virtually unaffected H-? line to be blocked, blocking the remaining wavelengths. The increase in contrast is so great that it becomes possible to even see the Horsehead nebula using a 10-12-inch telescope.
The filter is not worth using in telescopes with a diameter less than 20 cm, because they do not collect enough light to make the signal strong enough for the observer's eye.
There are not so many objects in the sky, for which it is worth using the H-beta filter, but its use often determines the ability to see the object or not. • visual observations under the dark sky: very good despite limited facilities
• visual observations under the urban sky: not applicable
• photography on film: sometimes right, sometimes not; very long exposure times required
• CCD photography: good when used with an additional IR filter
• unmodified SLR photography: very good
• photography of a reflex camera modified for astrophotography: very good
• webcam / video cameras for planetary photography: not applicable
• webcam / video cameras when photographing nebular objects: not applicable • transmits almost 100% of the H-beta line
• completely cuts out unnecessary lengths of the wave
• diffraction-limited accuracy
• parchocal with other Astronomic filters
• thickness: 1 mm
• resistant to moisture, scratch, does not age 
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