Baader Filters f/2 Ultra-Highspeed SII CMOS 1.25" (70942)

SII filters are narrowband filters designed for nebula photography, passing light at a wavelength of 672nm with a bandpass of 3nm. These filters are ideal for imaging most emission nebulae, planetary nebulae, and supernova remnants.

If you aim 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 a must-have addition to your collection after H-alpha and OIII filters. Like the H-alpha filter, the SII filter is a deep red filter near 672nm. Together, H-alpha, OIII, and SII filters enable tri-color narrowband imaging that creates the distinctive Hubble look for many emission nebulae. These filters can be used even when the moon is up, allowing you to continue imaging without interruption.

Specifications:

    Central Wavelength (nm): 671.7
    Half-Value Width (nm): 4
    Frame Type: 1.25"
    Mount Material: Aluminium
    Coating: Reflex-Blocker™
    Connection (to Telescope): 1.25"
    Filter Thickness (mm): 2

Compatibility and Applications:

    Appropriate for f/ratio: f/3.4 - f/1.8
    Type: Line filter
    Series: f/2 Ultra-Highspeed

Applications:

    Useful for photographs: Yes
    Visually useful: No
    Twin stars, Moon & Planets: Not suitable
    Nebulae & Galaxies: Ideal

The SII filter is an essential tool for astrophotographers aiming to capture stunning tri-color narrowband images of nebulae with high contrast and detail, even in light-polluted conditions or during moonlit nights.