Highlights

• Baader H-Beta Narrowband Filter Precision Grade
• 5.5 nm FWHM, recommended for optical systems from f/15 to f/1.8
• Reflex-Blocker hard coated and Plane-optically polished with sealed coating edges (Life-Coat)
• Blackened edges all around, with filter-lead-side-indicator in the form of a telescope-sided black outer rim
• Optimized for modern CMOS cameras, but likewise excellent for CCD camera technologies

Baader H-Beta-Filter theH-Alpha-Filterfor visual observations!

TheBaader H-Beta-Filter with 5.5nm half band widthis especially useful at 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.

AboutBaader H-alpha Filtersand why they aren’t suited for visual observations

The development of narrow-band H-Alpha-filters soon proved to be a “Game-Changer” for Amateur-Astrophotographers. No other spectral line of emission nebulae will give you so much information for the creation of “pretty pictures” as this Hydrogen-line. This is supported by the better coatings, sensitive CCD-cameras, motorized focusers and last but not least the the incredible tracking precision of modern mounts, which allow for very long exposure times with very narrow-band filters. Modern images are often based on exposure times of 30 hours through the three common, very narrow-band nebula filters. But to make use of this, the mount must provide “subpixel”-tracking, the focuser must not flex even for a micron, and its motor must compensated for temperature changes by keeping the focus up to a fraction of a millimeter… All this is possible but you need high-end equipment.

This is not necessary for visual observations.But unfortunately, we do not profit from those photographically wonderful filters when we are looking through the eyepiece at low intensities at night, the human eye is almost blind for this part of the spectrum. During daylight, when there is plenty of light, we can easily see H-Alpha. But at night and low-light, we can’t perceive these wavelengths. In contrast to a camera, our eyes also can’t add upp the light.

Because of this, most visual observers use the well-knownO III-filter