ZWO IR-blocking filter D21

ZWO IR-blocking filter D21 is a special interference filter that blocks unwanted infrared light and protects your ZWO ASI camera from dust and moisture. For refractors, this filter prevents focus shift between visible and IR light, leading to sharper images. For reflecting telescopes, a clear glass filter is sufficient, but with the IR blocker you are ready for all conditions.

Key benefits
✓ 90 % transmission in visible light for brightness without color transition
✓ IR-blocking coating prevents blur caused by IR focus shift
✓ Protects sensor from dust, moisture and scratches during long sessions
✓ Loose D21 filter fits directly into M42 filter wheels or camera mount
✓ Interference technology minimizes reflections and preserves contrast

Practical application
Screw this filter as the first element in your filter wheel or directly on the camera to eliminate IR light leaks. Use with refractors for maximum sharpness and keep your sensor clean. Combined with narrowband or color filters improves overall image sharpness and color fidelity.

Technical specifications

• Format: loose D21 filter (M42 × 0.75)
• Type: IR-blocking interference filter
• Transmission: 90 % in visible spectrum
• Coating: multi-layer anti-reflection
• Glass thickness: 2 mm
• Application: narrowband and broadband astrophotography (photographic)