Baader Filters OIII CMOS f/2 Ultra-Highspeed 50.4mm (70939)

OIII filters are designed to transmit only light with a wavelength of 501 nanometers, which corresponds to the spectral lines of doubly ionized oxygen. These specific lines are emitted by planetary nebulae and some emission nebulae. By blocking out other wavelengths, these filters make these objects visible while increasing contrast, allowing faint nebulae to be observed for the first time.

Astrophotography Applications

These filters are particularly well-suited for use with monochrome cameras. For optimal results, images captured using OIII filters are often combined with those taken using H-alpha and SII filters. This combination produces high-contrast images that clearly reveal faint nebulae.

Specifications

    Central Wavelength (nm): 500.7
    Half-Value Width (nm): 4
    Frame Type: Ring
    Mount Material: Aluminium
    Coating: Reflex-Blocker™
    Filter Thickness (mm): 2
    Filter Size (mm): 50.4

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 aiming to capture detailed and high-contrast images of nebulae by isolating their characteristic emissions.