Baader Narrowband SII Filter CMOS f/2 Highspeed 31mm

Baader Narrowband SII Filter CMOS f/2 Highspeed 31mm: narrowband for extremely fast optics

The sulfur line (SII) is the third channel of the classic Hubble palette. This filter isolates this line with a full-width at half-maximum (FWHM) of 6.5 nm and completes SHO composites. The f/2 Highspeed version is specially designed for extremely fast optics: the passband is pre-shifted so that the filter continues to operate at the correct wavelength at focal ratios from f/3.4 to f/1.8.

For fast systems such as a Celestron RASA or Hyperstar, the light hits the filter at steep angles, causing the passband of a standard filter to shift and signal to be lost. The Highspeed series compensates for this and maintains full transmission on the SII line.

CMOS-optimized

The filters are optimized for modern CMOS cameras: the 6.5 nm full-width at half-maximum 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 sealing make the coating resistant to years of use.

What you use this filter for

This filter is made for Hubble palette images (SHO) of emission nebulae, together with H-alpha and OIII. Due to the narrow passband, the sky background becomes deep dark, even under light-polluted skies or in moonlight, and the deep red nebula structure is brought out to the maximum.

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.