The new Baader CMOS-optimized S-II 4nm / 6.5nm Highspeed F/2 filter is a precision-grade narrowband filter with a high transmission at the Sulphur-II line at 671.7nm. The Highspeed F/2 versions are specifically designed to work very well with modern highly-sensitive astronomy cameras and telescopes with extremely fast focal ratios faster than f/2.3 such as the Celestron RASA astrographs.
The ultra-narrow 4nm bandpass makes this ideal for imaging under light-polluted skies. The 6.5nm versions are recommended for most cases where there is not a great deal of light pollution.
Baader's CMOS-optimized filters have excellent halo and reflection control, increased contrast and even more narrow passbands than previous generations. These filters set the new standard for monochrome astrophotography with CMOS sensors.
A special 47.4mm size is available for use with Baader's FCCT Filter Changer Camera Tilter for the Celestron RASA 8" and QHY cameras.
Baader CMOS-optimized filters - advantages
- Very high contrast due to steep edges of the coating
- Reflex-Blocker coatings to minimize reflections caused by correctors, reducers and other optical elements
- Standardized thickness for maximum possible parfocality - less need to refocus due to different filter thicknesses
- Blackened edges with side markings in the form of a black outer rim on the telescope side
- Each filter is individually fine-polished and coated with sealed coating edge, preventing moisture ingress
- Life-Coat for hardness and age-resistance, making the filters able to withstand tougher conditions for longer
For more information on Baader's new generation of CMOS-optimized filters, check out this blog post!
|4 nm / 6.5 nm
|Suitable for f/ratio
Reflex-Blocker hard coated, planeoptically polished
|Filter thickness 1.25", 2", 31 mm, 36 mm
|2 mm (without cell), 6 mm with cell
|Filter thickness 50.4 mm, 50 x 50 mm, 65 x 65 mm
|1.25", 31 mm, 36 mm, 2", 50.4 mm round, 50 x 50 mm square, 65 x 65 mm square