Explore Scientific CLS 1.25 inch City Light Suppression Filter

The Explore Scientific CLS 1.25" filter is a broadband light pollution suppression filter that dramatically improves the visibility of deep-sky objects from urban and suburban locations. By selectively blocking the most common artificial light wavelengths while transmitting the critical emission lines of nebulae and galaxies, it reveals celestial wonders that would otherwise be lost in the glow of city lights.

Advantages

This filter employs multi-layer dielectric coatings on high-quality optical glass to deliver exceptional contrast enhancement. It effectively suppresses high and low-pressure sodium vapor and mercury vapor emissions, which are the primary sources of light pollution. At the same time, it transmits H-alpha, H-beta, OIII, and S-II wavelengths, ensuring that emission nebulae, planetary nebulae, and many galaxies appear brighter and more detailed. The result is a darker sky background and significantly improved signal-to-noise ratio, with minimal dimming of stars.

Suitable for

• Visual observation of emission nebulae (e.g., Orion Nebula, Lagoon Nebula)
• Planetary nebulae and supernova remnants
• Galaxies with strong emission lines from light-polluted skies
• Astrophotography with 1.25" camera adapters

Key specifications

• Filter type: City Light Suppression (CLS)
• Filter size: 1.25 inch (31.75 mm clear aperture)
• Mounting thread: M28.5 x 0.6 (standard 1.25" filter thread)
• Optical design: Broadband light pollution filter
• Substrate: High-quality optical glass
• Coatings: Multi-layer dielectric
• Housing: Anodized aluminum
• Compatibility: Standard 1.25" eyepieces, diagonals, and camera adapters
• Included accessories: Protective plastic case

Recommendations

For best results, use this filter with telescopes of 80mm aperture or larger under moderately light-polluted skies. It is not intended for solar observation. Store in the provided case when not in use to protect the optical surfaces.