Chroma 3nm H-alpha filter
The filter H-alpha 3nm from Chroma is a very narrow-band filter designed for astronomical imaging, particularly suited to capturing nebulae rich in ionized hydrogen. With a bandwidth centered on the H-alpha line at 656.3 nm, it offers exceptional deep-sky performance, even under conditions of light pollution.
Key features
- Bandwidth : 3 nm, enabling precise isolation of the H-alpha line while suppressing unwanted wavelengths.
- High transmission : Up to 90 % at 656.3 nm, guaranteeing an excellent signal-to-noise ratio.
- Optical quality :
- Surface polished to an accuracy of λ/4.
- Multilayer anti-reflective coating on both sides to prevent halos and stray reflections.
- Available formats :
- 1.25" (mounted)
- 2" (mounted)
- 31 mm and 36 mm (unmounted)
- Substrate thickness : Approx. 2 mm.
Technical advantages
- Enhanced contrast :
- Effectively eliminates stray lines, especially those from mercury vapor and sodium lamps.
- Significant reduction of sky background for maximum contrast.
- Imaging under light pollution : Ideal for astrophotographers working in urban or suburban areas.
- Compatibility with high-speed systems :
- Optimized for focal ratios up to f/4.0 or less.
- Available in a "High-Speed" version for very fast systems (f/2.6 to f/3.6), compensating for blueshift.
- Various applications:
- Imaging diffuse and planetary nebulae.
- Capturing supernova afterglow rich in ionized hydrogen.
Prices and availability
- 3nm H-alpha filter mounted in 2" : Approx. €1,669, with a typical delivery time of 3 to 5 weeks.
- Other formats available : Prices vary according to size and assembly.
Conclusion
The filter Chroma H-alpha 3nm is an essential tool for astrophotographers seeking to maximize contrast and image quality in deep-sky imaging. Its optical precision, high transmission and ability to handle light pollution make it a top-of-the-range choice for capturing the subtle details of nebulae rich in ionized hydrogen.
