Baader Ultra-Narrowband Filter Set 3.5/4nm (H-alpha/O-III/S-II)
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Vai al moduloThe Baader Ultra-Narrowband Filter Set 3.5/4nm (H-alpha / O-III / S-II) is the even narrower-band version of the Baader CMOS-Optimized range, designed for maximum possible contrast even under heavily light-polluted skies (Bortle 9/8/7/6), for tri-colour imaging of emission nebulae according to the "Hubble" palette (SHO).
Three filters, ultra-narrow band
The set includes an H-alpha filter (656.3nm, 3.5nm FWHM), an O-III filter (500.7nm, 4nm FWHM) and an S-II filter (671.7nm, 4nm FWHM), optimized for optical systems from f/10 to f/3.5. Compared to the standard Narrowband version (6.5nm), the narrower passband allows for even greater contrast, further reduces the apparent size of stars and reveals the finest nebula details — essential under heavy urban light pollution.
Baader CMOS-Optimized technology
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 formats
Available in 7 formats: 1¼" (31.8mm), 2" (50.8mm), 31mm, 36mm, 50.4mm, 50×50mm and 65×65mm.
Technical specifications
| Parameter | Value |
|---|---|
| Filters included | H-alpha, O-III, S-II |
| Central wavelengths | 656.3 / 500.7 / 671.7 nm |
| Bandwidth (FWHM) | 3.5 / 4 nm |
| Recommended optical systems | f/10 to f/3.5 |
| Filter thickness | 2 mm |
| Coating | Reflex-Blocker™, Life-Coat™ |
| Brand | Baader Planetarium |
Who it's for
Ideal for astrophotographers working under heavily light-polluted skies who want the maximum possible contrast for false-colour "Hubble Palette" style images of emission nebulae, planetary nebulae and supernova remnants. Compatible with filter wheels and most mono CMOS cameras for astrophotography.