Baader Ultra-Narrowband Filter Set 3.5/4nm 2" (H-alpha/O-III/S-II)
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Vai al moduloThe Baader Ultra-Narrowband Filter Set 3.5/4nm 2" (H-alpha / O-III / S-II) is the even narrower-band version of the Baader CMOS-Optimized range, designed for maximum contrast even under strongly light-polluted skies (Bortle 9/8/7/6), for tri-color imaging of emission nebulae in the "Hubble" palette (SHO).
Three filters, ultra-narrow bandwidth
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 bandwidth allows even greater contrast, further reduces apparent star size, and reveals the finest nebula details — essential under strong 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 peel, degrade, and lasts the entire life of the filter even in 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.
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 |
| Format | 2" (50.8mm), M48 thread |
| 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 under strongly light-polluted skies who want maximum contrast for false-color images in the "Hubble Palette" style of emission nebulae, planetary nebulae and supernova remnants. Compatible with 2" filter wheels and most monochrome CMOS cameras for astrophotography.