The Dark Clear Skies 2″ 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 darken the background sky when imaging under light-polluted conditions.
Unlike narrowband or UHC filters, a CLS filter maintains a more natural colour balance, making it suitable for a wide range of deep-sky objects.
Key Features
- Reduces the effects of artificial light pollution
- Improves contrast and background sky darkness
- Broadband transmission for more natural colour balance
- Standard 2″ mounted filter format
- Suitable for astrophotography and EAA
Compatibility
Designed to fit standard 2″ (M48 × 0.75) filter threads commonly used in filter wheels, filter drawers, eyepieces, 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
| Filter Type | CLS (City Light Suppression) |
| Filter Size | 2″ (M48 × 0.75) |
| Clear Aperture | Approx. 45 mm |
| Substrate | Optical-grade glass |
| Coatings | Multi-layer interference coatings |
| Filter Cell | Anodised aluminium |
| Application | Astrophotography, EAA |
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.