Skip to content

Baader H-beta 8.5nm CCD Narrowband Filter

$136.00
SKU FHBN-1 (Baader #2458425)
Filter size

Note: To enquire or to place an order please press the Add to Quote button and add as many products to the quote as you are interested in. Add any questions or comments in the Message field. We will then get back to you to discuss your requirements. Alternatively, give us a call.

Click for further details on ordering, payment and shipping.

Description
  • 1¼" Baader H-Beta CCD-filter 8,5nm with 1¼" (28,5mm) filter thread
  • For focal ratios between f10 and f2.8
  • H-Beta-CCD-narrowband-filters can also be used for visual observations! (A high-quality alternative to the old Lumicon-H-Beta-Filters)
  • Antireflection-coatings, fineoptically polished

Baader H-Beta-Filter – the H-Alpha-Filter for visual observations!

The Baader H-Beta-Filter with 8.5nm half width is 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 wont 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.

About Baader H-alpha Filters and 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 millimetre... 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 cant perceive these wavelengths. In contrast to a camera, our eyes also cant add up the light.

Because of this, most visual observers use the well-known O III-filter. The human eye has got its highest sensitivity between 500nm and 520nm, where we can observe many structures in supernova-remnants, planetary nebulae and so on. But they are pretty useless for deep sky objects which shine mainly in H-alpha.

The alternative – Baader H-Beta filter for visual applications

For the H-alpha-objects mentioned above, the H-beta-line is a good option: At 486nm, it still quite close to the region of highest sensitivity of our eye. Because of quantum-mechanical coupling with H-Alpha, we can usually see the same structures. H-Beta-filters are much more efficient than O-III, because most nebulae emit hydrogen-light – although H-Beta is not as popular as H-Beta.

A H-beta filter can be regarded as a visual H-Alpha-filter.

The H-Beta-spectrum is indeed very interesting. Quantum-mechanics define a fixed ratio between H-Alpha and H-Beta, but because of the shorter wavelengths, H-Beta has got a higher energy. That's why H-Beta suffers from a higher extinction rate in interstellar dust regions, which can easily be detected. The ratio between H-Beta and H-Alpha gives you information about the amount of dust between us and the source, which is especially interesting for scientific work. For astrophotography, you can scale down the intensity of H-Alpha to simulate an H-Beta-filter – and if you are observing with your eyepiece, you will see structures which were almost invisible before.

Visual observers profit from the fact that a H-Beta-filter can show the dust regions in hydrogen-emitting nebulae quite clearly, similar to a photo-graphical H-Alpha-filter. Larger telescope apertures can even show the split-up into two lines – and the soft phase-out towards the edge.

The filter is almost as impressive when you are looking at the dust tails of comets. Especially light with shorter wavelengths will be scattered more in the dust tail, so that the contrast to its surroundings increases. Light with even shorter wave-lengths will be scattered even more, but our eye is not so sensitive for these parts of the spectrum. The true dimensions of the sometimes very long dust tail may only be recognizable in the eyepiece with the help of a H-Beta-filter. The H-Beta line is also outside of the prominent lines of the gas tail, so the dust tail can be better discerned from the gas tail – and the contrast is increased even more.

Conclusion:

A dielectric H-Beta-filter is no allround-filter like e.g. a Neodymium-Skyglow-filter. But it is the best available tool to see faint details, because you can visually see the dominating hydrogen emission lines in the sky – something which an O-III-filter cant show you. Together with an O-III-filter, it covers the most important spectral lines of emission nebulae and is an important tool for visual deep-sky-observers.

Why Baader Planetarium Filters?

Transmission Curve
H-Beta Transmission Curve
H-Beta Transmission Curve
Specifications

1.25"

MANUFACTURER Baader Planetarium
SKU (#) 2458425
EAN CODE 4047825009302
WEIGHT (KG) 0.059
TRANSMISSION RANGE H-beta
FILTER THICKNESS (WITHOUT CELL) 2 mm
HBW (HALFBANDWIDTH) 8.5nm
CWL (CENTRAL WAVELENGTH) 486 nm
AR-COATING dielectrically coated, planeoptically polished
FILTER SIZE 1 25 inch
FILTER USAGE CCD, H-Beta, IR-Cut
FILTER MOUNTED Mounted (LPFC 6mm)
TYPE OF FILTER Narrowband
SINGLE OR SET? Single Filter
FILTER SHAPE round

2"

MANUFACTURER Baader Planetarium
SKU (#) 2458426
EAN CODE 4047825009296
WEIGHT (KG) 0.065
TRANSMISSION RANGE H-beta
FILTER THICKNESS (WITHOUT CELL) 2 mm
HBW (HALFBANDWIDTH) 8.5nm
CWL (CENTRAL WAVELENGTH) 486 nm
AR-COATING dielectrically coated, planeoptically polished
FILTER SIZE 2 inch
FILTER USAGE CCD, H-Beta, IR-Cut
FILTER MOUNTED Mounted (LPFC 6mm)
TYPE OF FILTER Narrowband
SINGLE OR SET? Single Filter
FILTER SHAPE round

50.8mm

MANUFACTURER Baader Planetarium
SKU (#) 2458427
EAN CODE 4047825009289
WEIGHT (KG) 0.07
TRANSMISSION RANGE H-beta
FILTER THICKNESS (WITHOUT CELL) 3 mm
HBW (HALFBANDWIDTH) 8.5nm
CWL (CENTRAL WAVELENGTH) 486 nm
AR-COATING dielectrically coated, planeoptically polished
FILTER SIZE 50.8 mm
FILTER USAGE CCD, H-Beta, IR-Cut
FILTER MOUNTED Unmounted
TYPE OF FILTER Narrowband
SINGLE OR SET? Single Filter
FILTER SHAPE round

50x50mm

MANUFACTURER Baader Planetarium
SKU (#) 2458428
EAN CODE 4047825022820
WEIGHT (KG) 0.074
TRANSMISSION RANGE H-beta
FILTER THICKNESS (WITHOUT CELL) 3 mm
HBW (HALFBANDWIDTH) 8.5nm
CWL (CENTRAL WAVELENGTH) 486 nm
AR-COATING dielectrically coated, planeoptically polished
FILTER SIZE 50 x 50 mm
FILTER USAGE CCD, H-Beta, IR-Cut
FILTER MOUNTED Unmounted
TYPE OF FILTER Narrowband
SINGLE OR SET? Single Filter
FILTER SHAPE square
Downloads