Astronomik Filters CLS M67 (66935)

The Astronomik CLS is an affordable filter designed for visual observation, black-and-white photography, and CCD imaging of nebulae, galaxies, and star clusters. It is compatible with astronomical instruments of any size. Since 2008, the filters have been redesigned to eliminate halos and unwanted reflections, ensuring improved performance.

Light Pollution Reduction
This filter blocks the spectral lines of mercury and sodium-vapor lamps while allowing most visible light and H-alpha emissions to pass. It enhances contrast by preserving important emission lines and the spectral range visible to dark-adapted eyes. This makes it highly effective for reducing light pollution in both astrophotography and visual observation.

Optimized Usage
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: Ideal for DSLR cameras (modified or unmodified), CCD cameras, and black-and-white film photography.
• Visual Observation: Effective in dark-sky conditions to reduce light pollution from artificial sources. It also enhances the visibility of nebulae and galaxies.

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 added durability.

Build Quality and Compatibility
The filter features an aluminium mount in an M67 frame format. It is resistant to scratches, humidity, and aging effects, ensuring long-term reliability. Astronomik CLS filters are parfocal with other Astronomik filters, maintaining excellent optical performance. They are delivered in a durable plastic storage box for safe handling and protection.