The Astronomik H-beta filter is specifically designed for visual observation, particularly effective with larger aperture instruments. It allows the H-beta emission line to pass almost unobstructed while blocking the rest of the spectral range. This filter significantly enhances contrast, making observation of objects like the Horse Head Nebula feasible with telescope apertures ranging from 10″ (250mm) to 12″ (300mm).

For optimal use, the Astronomik H-beta filter is recommended for aperture ratios between 1:4.5 and 1:6.

The filter is most effective when used with telescopes of 8″ (200mm) or larger, ensuring sufficient light gathering. Its high optical quality ensures that stars remain sharp, comparable to observation without any filter.

The Astronomik H-beta filter excels in enhancing the contrast between hydrogen nebulae and the sky background, crucial for visual observation even from dark sky areas. It allows for the observation of low-contrast hydrogen regions that are nearly imperceptible without filters.

Overall, the Astronomik H-beta filter is a crucial tool for deep-sky observers seeking to explore the depths of H-beta emission regions.

Suitability of the Astronomik H-beta filters

• Visual observation (dark skies): Very good, but only suitable for a few observation objects
• Visual observation (urban skies): Unsuitable

Technical data

• Typical transmission of 97% transmission at 486nm (H-beta)
• Transmission range: 480nm to 492nm
• Full-Width-Half Maximum (FWHM): 12nm
• Glass thickness: 1mm (except Astronomik OWB Type 3 and XT filters)
• Finely polished optical glass, free of any striae, residual stresses, and bubbles
• Extremely scratch-resistant and durable coating
• Completely resistant against high humidity and aging effects
• Astronomik MFR coating (Astronomik Deep-Sky RGB, UV-IR Block L-1, L-2, L-3, and Narrowband-Emissionline filters)
• Parfocal with other Astronomik filters
• Diffraction-limited
• Optimized spectral windows
• Delivered in a high-quality, long-lasting