Baader S-II 2" unmounted f/2 Highspeed Filter 4 nm CMOS optimized (2961528U)

Baader S-II 2" unmounted f/2 Highspeed Filter 4 nm CMOS optimized (2961528U)

Description

The Baader S-II 2" unmounted (Ø 47.4 mm, 2 mm thick) f/2 Highspeed Filter 4 nm is designed for extremely fast optical systems like the Celestron RASA f/2 astrographs. It is specially selected for Baader FCCT (Filter Changer Camera Tilter) filter sliders, compatible with QHY cameras and other models.

Optimized for CMOS sensors, it also delivers excellent results with CCD cameras. With a central wavelength of 671.7 nm and a 4 nm bandwidth, this filter isolates the sulfur-II emission line (S-II), making it essential for narrowband astrophotography and SHO (Hubble) palette imaging when combined with H-alpha and O-III.

Its precision planeoptical polishing and Reflex-Blocker™ hard coating minimize reflections, while blackened edges with telescope-side indicator ensure proper installation. The Life-Coat™ sealed protection guarantees long-term durability. Lightweight (0.01 kg) and robust, it is sold individually and provides maximum contrast even under strong light pollution (Bortle 9 to 6).

Technical Specifications

• Manufacturer: Baader Planetarium

• Product SKU: 2961528U

• EAN code: 4047825051028

• Net weight: 0.01 kg

• Filter type: S-II f/2 Ultra Highspeed

• Mount: unmounted

• Shape: round

• Diameter: 47.4 mm (2" without cell)

• Thickness: 2 mm

• Central wavelength (CWL): 671.7 nm

• Half bandwidth (HBW / FWHM): 4 nm

• Transmission: S-II line

• Coating: Reflex-Blocker™ hard coated, planeoptically polished

• Durability: Life-Coat™ sealed edges

• Edges: blackened with telescope-side indicator

• Suitable f/ratio: < f/2.3

• Compatibility: Celestron RASA 8", Baader FCCT, QHY cameras, CMOS and CCD

• Application: S-II astrophotography, nebulae, SHO palette, light-polluted skies

• Packaging: single filter