Baader Narrowband OIII Filter CMOS f/2 Highspeed 1.25 inches

Baader Narrowband OIII Filter CMOS f/2 Highspeed 1.25 inch: narrowband for extremely fast optics

Doubly ionized oxygen (OIII) is the dominant emission line of planetary nebulae and supernova remnants such as the Veil Nebula. This filter isolates that line with a half-width of 6.5 nm. The f/2 Highspeed version is specially designed for extremely fast optics: the passband is pre-shifted, so the filter continues to work at the correct wavelength for apertures from f/3.4 to f/1.8.

In fast optical systems like the Celestron RASA or Hyperstar, light strikes the filter at steep angles, causing the transmission band of a standard filter to shift and leading to signal loss. The Highspeed series compensates for this and maintains full transmission at the OIII line.

CMOS-optimized

The filters are optimized for modern CMOS cameras: the 6.5 nm FWHM has been chosen for balanced exposures across the channels, and the Reflex-Blocker hard coating suppresses halos around bright stars. Blackened edges and the Life-Coat edge seal make the coating resistant to years of use.

What you use this filter for

This filter is designed for planetary nebulae, the Veil Nebula, and oxygen-rich regions of emission nebulae. The narrow bandpass makes the sky background deeply dark, even under light-polluted skies or moonlight, and makes the blue-green nebula structures stand out maximally.

Featured accessories

Combine this filter with the other two lines in the series (H-alpha, OIII, and SII) for complete narrowband or Hubble palette captures.

For whom yes and for whom no

• ✓ Astrophotographers with fast optics (f/1.8 to f/3.4) such as RASA and Hyperstar systems
• ✓ Who wants to shoot narrowband under a light-polluted sky
• Owners of slower telescopes (f/4 and slower): the standard Baader Narrowband series without preshift is the right choice.

Specifications

You can find more accessories for this merk at the Baader merk Page.