Astronomik H-beta 2"

Astronomik H-beta visual 2" — for faint hydrogen nebulae

The Astronomik H-beta filter is designed for visual observation with larger telescopes. It passes the 486 nm H-beta line almost unobstructed while blocking the rest of the spectrum, so low-contrast hydrogen regions that are nearly invisible without a filter can stand out against the sky.

Classic targets

With telescopes of 10 to 12 inches (250–300 mm) aperture, the H-beta filter makes objects such as the Horsehead Nebula observable. It works best on telescopes of 8 inches (200 mm) or larger, and Astronomik recommends focal ratios between f/4.5 and f/6. Stars stay as sharp as without a filter.

When to use it

Astronomik rates the H-beta filter as very good under dark skies, but useful for only a few objects. It is unsuitable for urban skies; for general nebula observing there, the UHC or OIII filters are the better choice.

Optical

Physical

Manufacturer documentation

Astronomik H-beta visual 2" product page

Compatibility notes

Visual H-beta 2-inch (10214200). Product page gives f/4.5–f/6; Astronomik category page says f/4–f/6; product page value used. Unsuitable for urban skies.

Additional specifications