Optolong H-alpha Filter 7nm 1.25 inches

Optolong Filters H-alpha 7nm 1.25″ is a high-quality narrowband filter that passes only the H-alpha emission line (656.3 nm) with a bandwidth of 7 nm. This isolates red light from hydrogen-rich nebulae, while effectively blocking interfering wavelengths such as those from sodium and mercury lamps. The result is a darker sky background and more contrast, even in urban areas with high light pollution.

This filter captures emission nebulae such as the Orion Nebula, the Rosette Nebula and the North American Nebula with great detail. Thanks to its wider bandwidth of 7 nm, compared to ultra-small filters of 3 nm, this filter is less critical in terms of optical setup and therefore also suitable for use with telescopes with a relatively short focal ratio. The filter is made of high-quality optical glass and features multiple anti-reflection coatings for maximum light transmission and minimal reflections.

The rugged 1.25″ aluminum mount makes the filter suitable for virtually all standard eyepieces, filter wheels and adapters. Although the filter is primarily intended for astrophotography, it can also provide limited visual effect in bright nebulae in medium-sized telescopes.

Observation goals
This filter is ideal for astrophotographers who want to capture emission nebulae with color cameras, modified DSLRs or monochrome cameras. It offers an excellent balance between high contrast and broad applicability. For visual use, the added value remains limited, but in photography it delivers marked improvements even under moonlight or urban skies.

Specifications

• Type: H-alpha narrowband filter
• Bandwidth: 7 nm around 656.3 nm
• Diameter: 1.25″ mount
• Material: Optical glass with multiple anti-reflection coating
• Mount: Aluminum
• Application:
  • ✓ Astrophotography of emission nebulae
  • ✓ Suitable for color cameras, DSLRs and mono cameras
  • ✓ Effective under light pollution and moonlight
  • ✗ Limited suitability for visual use