Baader Filters OIII CMOS f/2 Ultra-Highspeed 2" (70938)

OIII filters allow only light with a wavelength of 501 nanometers to pass through, corresponding to the spectral lines of doubly ionized oxygen. These specific lines are emitted by planetary nebulae and certain emission nebulae. By blocking out other wavelengths, the filter enhances contrast, making faint nebulae visible even in challenging conditions for the first time. 

Astrophotography Use 

These filters are most effective when paired with monochrome cameras. For the best results, images taken with OIII filters are typically combined with those captured using H-alpha and SII filters. This combination produces high-contrast images that clearly depict faint nebulae in exceptional detail. 

Specifications

    Central Wavelength (nm): 500.7
    Half-Value Width (nm): 4
    Frame Size: 2"
    Mount Material: Aluminium
    Coating: Reflex-Blocker™
    Connection (to Telescope): 2"
    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

OIII filters are an essential tool for astrophotographers seeking to capture detailed, high-contrast images of nebulae while isolating their characteristic emissions.