The Dark Clear Skies 1.25″ CLS (City Light Suppression) Filter is designed to reduce the effects of artificial light pollution while maintaining good transmission of natural starlight and broadband astronomical targets.

Purpose & Use

CLS filters are broadband light pollution filters intended to suppress common wavelengths produced by street lighting while preserving much of the visible spectrum. This helps improve contrast and background sky darkness when imaging or observing under light-polluted skies.

Unlike narrowband or UHC filters, a CLS filter maintains a more natural colour balance, making it suitable for a wide range of deep-sky targets.

Key Features

• Reduces the effects of artificial light pollution
• Improves contrast and darkens background sky
• Broadband transmission for natural colour balance
• Standard 1.25″ mounted filter format
• Suitable for astrophotography and EAA

Compatibility

Designed to fit standard 1.25″ (M28.5 × 0.6) filter threads commonly used in eyepieces, filter wheels, and imaging adapters.

Typical Applications

• Broadband deep-sky astrophotography
• Galaxies, star clusters, and reflection nebulae
• Electronically Assisted Astronomy (EAA)
• Imaging under suburban or urban skies

Technical Specifications

If you are unsure whether a CLS filter is suitable for your imaging setup or observing conditions, feel free to contact us for advice before purchase.