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The set includes an H-alpha filter, an O-III filter and an S-II filter, all with a 6.5nm FWHM passband, but with a central wavelength pre-shift (CWL-preshift) specifically calibrated to perfectly match optical systems from f/3.4 to f/1.8. In extremely fast optical trains, standard narrowband filters risk having the CWL shift out of the passband itself; these Highspeed filters solve the problem, offering maximum contrast even at these extreme apertures.
Each filter is coated with Reflex-Blocker™ treatment, which eliminates unwanted reflections even in the presence of auxiliary optics, and with Life-Coat™ technology: a hardened coating that does not flake, does not degrade and lasts the filter's entire lifetime even under the most extreme conditions. The edges are blackened all around, with a visual indicator on the front side for correct orientation during mounting. Each filter is individually polished and coated, with no exposed coating edges.
Available in 7 formats: 1¼" (31.8mm), 2" (50.8mm), 31mm, 36mm, 50.4mm, 50×50mm and 65×65mm.
| Parameter | Value |
|---|---|
| Filters included | H-alpha, O-III, S-II |
| Bandwidth (FWHM) | 6.5 nm |
| Recommended optical systems | f/3.4 to f/1.8 (ultra-fast astrographs) |
| Filter thickness | 2 mm |
| Coating | Reflex-Blocker™, Life-Coat™ |
| Brand | Baader Planetarium |
Essential for astrophotographers using ultra-fast astrographs such as Celestron RASA, Hyperstar systems or other optical trains between f/1.8 and f/3.5, where normal narrowband filters would not guarantee full transmission. Enables, for the first time, truly exploiting fast optics for high-contrast imaging of emission nebulae in "Hubble Palette" style (SHO).
