Baader Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 50x50mm (70905)

H-alpha Filter
The H-alpha filter transmits light at a wavelength of 656nm. It is the best option for narrowband H-alpha astrophotography, providing high-contrast imaging and revealing rich details of nebulae, even in areas with strong light pollution.

OIII Filter
The narrowband O-III 3nm filter is specifically designed for nebula observation. It allows a 3nm bandwidth of light centered on a wavelength of 500nm, corresponding to OIII emission lines, while blocking all other light.

SII Filter
The narrowband S-II 7nm filter transmits light at a wavelength of 672nm with a bandpass of 3nm. This filter is designed for nebula photography and is suitable for most emission nebulae, planetary nebulae, and supernova remnants.

If you want to replicate the iconic look of Hubble Space Telescope (HST) images—such as the famous "Pillars of Creation" in the Eagle Nebula (Messier 16)—the SII filter is an excellent addition to your collection after H-alpha (H-a) and OIII filters. Like the H-a filter, the SII (sulfur) filter operates in the deep red spectrum near 672nm. Combining H-a, OIII, and SII filters enables tri-color narrowband imaging, delivering that signature "Hubble look" for many emission nebulae. Additionally, these filters allow imaging during moonlit nights, ensuring your equipment remains productive without long delays.

Specifications

• Capacity:

  • Central wavelength: 656.3nm (H-alpha), 500.7nm (OIII), 671.7nm (SII)

  • Half-value width: 3.5nm (H-alpha), 4nm (OIII & SII)

• Frame:

  • Size: 50 x 50mm

  • Mount material: Aluminium

  • Coating: Reflex-Blocker™

• Compatibility:

  • Suitable for systems with f/10 to f/3.5

  • Filter thickness: 2mm

• General Information:

  • Type: Filters

  • Build type: Line filter

  • Series: Ultra-Narrowband

• Applications:

  • Useful for photography: Yes

  • Visually useful: No

  • Twin stars: No

  • Moon & planets: No

  • Nebulae & galaxies: Yes