Celestron H-Alpha H-Beta OIII Imaging Filter for RASA 8 | Nebula Filter

Celestron H-alpha H-beta OIII Imaging Filter, Rowe-Ackermann Schmidt Astrograph (RASA) 8

Bring out the finest detail in emission nebulae with Celestron’s Hα-Hβ-OIII Imaging Filter, precision-engineered for the 8” Rowe-Ackermann Schmidt Astrograph (RASA). This narrowband filter dramatically enhances contrast and clarity in your deep-sky images by selectively passing light at the key wavelengths emitted by nebulae—H-alpha, H-beta, and doubly ionised oxygen (OIII)—while effectively blocking unwanted light pollution.

Whether you're imaging from an urban backyard or a remote dark-sky site, this filter helps reveal delicate nebular structures that would otherwise be lost in background glow.

Key Features

• High Transmission at Critical Wavelengths
  Allows more than 85% light throughput at H-alpha (656nm), H-beta (486nm), and OIII (496nm & 501nm) lines—maximising nebula brightness and contrast.

• Excellent Light Pollution Rejection
  Suppresses over 99.5% of other visible light, significantly reducing skyglow and interference from artificial lighting sources such as sodium and mercury vapour lamps.

• Purpose-Built for Nebula Imaging
  Perfect for photographing emission nebulae including the Orion Nebula (M42), North America Nebula (NGC 7000), Lagoon Nebula (M8), and the Carina Nebula (NGC 3372).

• Tailored for Fast Optics
  Designed to work optimally with the fast f/2.0 light cone of the RASA 8", preserving sharpness and image quality across the entire field.

What to Expect

This filter is ideal for astrophotographers who want to image emission nebulae in rich detail, even under moderately light-polluted skies. It is not recommended for broadband deep-sky targets such as galaxies or open clusters, as these objects emit across a wider range of wavelengths that the filter blocks.

Enhance Your Setup

Pair this filter with a dedicated astro camera for best results, and consider combining it with an automated filter wheel or monochrome imaging system for advanced workflows. The Hα-Hβ-OIII Imaging Filter offers a cost-effective way to transform your imaging setup and make the most of your RASA’s fast optics.

Achieve cleaner, higher-contrast images with bold nebular detail. Whether you're just getting started or refining a professional imaging rig, this filter gives your 8” RASA the edge in narrowband astrophotography.