The Baader H-Beta-Filter with 8.5nm half width is especially useful for telescopes with 8" or larger apertures or if you are working with large exit pupils. This narrowband-filter delivers a much higher contrast, compared to common visual H-beta-filters. H-Beta-nebule-filters with a wider half-width deliver a brighter image and will also show you e.g. the California nebula,but it won't be so clear, and you will miss many of its inner structures. Without any filter, this nebula (to name just one of many) will be completely invisible under brighter skies.
|FILTER THICKNESS (WITHOUT CELL)
||2 mm / 3 mm
|CWL (CENTRAL WAVELENGTH)
||dielectrically coated, planeoptically polished
||CCD, H-Beta, IR-Cut
||Mounted (LPFC 6mm) / Unmounted
|TYPE OF FILTER
|SINGLE OR SET?
||round / square