Astronomik Filters H-alpha 12nm CCD XT Clip filter for Canon EOS APS-C cameras (54609)

The Astronomik H-alpha filter is a specialized narrowband filter designed for CCD astrophotography. It allows the passage of H-alpha light emitted by nebulae while blocking nearly all other wavelengths where CCD cameras are sensitive. This significantly enhances contrast by isolating the H-alpha emission line and suppressing unwanted light, such as skyglow or artificial lighting.

The filter features a full width at half maximum (FWHM) of 12nm, optimized for use with common CCD cameras and fast optical systems. It achieves up to 99% transmission, ensuring excellent image quality. Unlike stronger filters like the 6nm variant, the 12nm version provides a higher likelihood of finding suitable guiding stars when using cameras with built-in autoguiders (e.g., SBIG). Its range of application spans f/2.8 to f/15 focal ratios, with minimal transmission losses or chromatic distortions in typical setups.

Main Functionality

The Astronomik H-alpha-CCD filter enhances contrast between objects by isolating the H-alpha emission line from the background skyglow. It effectively blocks artificial lighting emission lines from mercury (Hg) and sodium (Na) sources, as well as natural skyglow, making it ideal for imaging emission nebulae even in light-polluted areas.

Compatibility Note: The clip-filter system is compatible with most camera lenses, including Canon EF lenses and third-party brands like Sigma, Tamron, Tokina, and Walimex. However, Canon EF-S lenses are not compatible with clip-filters.

Specifications

• Transmission: Up to 99% at the H-alpha line (656 nm)
• FWHM: 12nm
• Material: Aluminium mount with optically polished substrate
• Glass Thickness: 1mm
• Parfocality: Compatible with other Astronomik filters
• Durability: Resistant to humidity, scratches, and aging effects

The Astronomik H-alpha filter is diffraction-limited, ensuring it does not degrade the optical performance of your telescope. Its robust design makes it an excellent choice for astrophotographers seeking high-quality imaging of emission nebulae under both light-polluted and dark-sky conditions.