Dual-Band 7nm H‑alpha & OIII Filter for OSC Cameras

Capture high-contrast nebula detail, even under city skies.

This dual-band 7nm H‑alpha & OIII filter is engineered for one-shot color (OSC) CMOS and CCD cameras, providing efficient light pollution suppression while isolating the key emission lines of many nebulae. With a narrow 7nm bandpass centered on Hydrogen-alpha (H‑a) and Oxygen III (OIII), it transmits the most important wavelengths for emission and planetary nebulae while blocking most unwanted artificial and natural skyglow.

Designed for telescopes at f/5 and slower, the filter enables long-exposure deep-sky imaging from suburban or urban locations, such as a balcony or backyard. By passing only the H‑a (red) and OIII (green‑blue) lines, it boosts contrast, reveals faint structures, and reduces the impact of moonlight and street lighting. This makes it easier to obtain full-color nebula images with a single exposure, simplifying both acquisition and post‑processing compared with multi-filter monochrome workflows.

Why It's a Smart Choice

• Dual 7nm narrowband design - Isolates H‑alpha and OIII emissions for high contrast on emission nebulae, planetary nebulae, and supernova remnants.
• Optimized for one-shot color cameras - Captures full-color data in a single imaging session, reducing complexity and processing time.
• Effective light pollution reduction - Suppresses most urban skyglow and moonlight, enabling deep-sky imaging from light-affected locations.

The filter is available in 1.25" and 2" sizes with M48 x 0.75 threading (for the 2" version), and is supplied in a durable PP plastic storage box for safe transport and storage.

FAQ

Q: Is this filter suitable for monochrome cameras?
A: It is optimized for one-shot color cameras, but can also be used with monochrome sensors if desired.

Q: Can I use it under a bright Moon?
A: Yes. The 7nm bandpass significantly reduces the impact of moonlight, making it useful during bright lunar phases.

Q: Which targets benefit most from this filter?
A: Emission nebulae, planetary nebulae, and supernova remnants with strong H‑a and OIII emission lines benefit the most.

Q: Does it alter the overall color balance?
A: The filter selectively passes H‑a and OIII lines while maintaining consistent color channels, allowing natural-looking nebula colors after standard calibration and processing.