Astronomik Filters CLS Clip Pentax K (66928)

The Astronomik CLS is an affordable filter designed for black-and-white photography, CCD imaging, and visual observation of nebulae, galaxies, and star clusters. It is compatible with astronomical instruments of any size. Since 2008, the filters have been redesigned to be "halo-free," eliminating unwanted reflections and improving overall performance.

Light Pollution Reduction
This filter effectively blocks the spectral lines of mercury and sodium-vapor lamps while allowing most visible light and H-alpha emissions to pass. It preserves important emission lines and the spectral range visible to dark-adapted eyes, making it ideal for reducing light pollution in astrophotography.

Optimized Performance
The Astronomik CLS filter is optimized for aperture ratios between 1:3 and 1:15. Transmission losses and chromatic distortions are minimal unless used with extremely bright aperture ratios (e.g., 1:2 or higher). It is suitable for telescopes of all aperture sizes.

Applications

• Photography: Excellent for DSLR cameras (modified or unmodified), CCD cameras, and black-and-white film photography.
• Visual Observation: While not ideal for urban skies, it works well in dark-sky conditions to reduce light pollution from artificial sources.

Compatibility
The clip-filter design has been successfully tested with Pentax K1 and K1 MkII camera bodies. It is also compatible with other Pentax systems.

Technical Specifications

• 92% transmission at 486nm (H-beta)
• 92% transmission at 496nm (OIII)
• 92% transmission at 501nm (OIII)
• 97% transmission at 656nm (H-alpha)
• Passes light from 450–540nm and beyond 650nm.
• Glass thickness: 1mm with multiple coatings for durability.

The filter features an aluminium mount in a clip-filter frame format. It is resistant to scratches, humidity, and aging effects. Astronomik CLS filters are parfocal with other Astronomik filters, ensuring no reduction in optical performance. They are delivered in a durable plastic storage box for long-term protection.