Baader Filters SII CMOS f/3 Ultra-Highspeed 31mm (75585)

The SII filter is a narrowband filter designed for astrophotography. It passes light at a wavelength of 672 nm with a bandpass of 3 nm, making it ideal for capturing emission nebulae, planetary nebulae, and supernova remnants.

If you want to replicate the appearance 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 and OIII filters. Like H-alpha, the SII filter is a deep red filter near 672 nm. The combination of H-alpha, OIII, and SII filters enables tri-color narrowband imaging, creating the iconic "Hubble look." These filters also allow imaging during moonlit nights, ensuring your equipment remains in use even when the moon is visible.

Specifications:

• Central wavelength (nm): 671.7

• Half-value width (nm): 4

Frame:

• Type: Ring

• Mount material: Aluminium

• Coating of optical system: Reflex-Blocker™

Appropriate for:

• Focal ratio range: f/3.4 - f/2.3

• Filter thickness (mm): 2

• Filter size (mm): 31

General Information:

• Type: Filters

• Type of build: Line filter

• Series: f/3 Ultra-Highspeed

Area of Application:

• Useful for photographs: Yes

• Visually useful: No

• Nebulae and galaxies: Yes

• Moon and planets: No