Baader SunDancer II H-alpha Filter

Product code: 1363056
in stock
£3,049.00 UK Price
£2,540.83 (ex. VAT) International Price
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Product information

  • Silently heated H-alpha-Filter with integrated 3x telecentric system with 2nm block filter.
  • Half-width (FWHM) of 0.6±0.1Å at an effective focal ratio of f/30
  • Resistant to ageing: The dielectric coating of the blocking filter and the airtight storage of the SolarSpectrum Etalon filter in oil prevent the ageing process
  • The complete disk of the sun as well as prominences are visible in telescope with focal lengths up to about 600mm
  • shows prominences and solar surface details for visual observations as well as for photography and bino-viewers
  • For telescope with 80mm aperture or less, no additional D-ERF (energy rejection filter) is necessary
  • Userfriendly electrical temperature control; additional micrometer screw for observiong fast changes in the blue wing of the H-alpha-line
  • Nosepiece: 2", 1,25"

The Baader SunDancer II (with heated H-alpha Etalon from SolarSpectrum) transforms an existing telescope quickly and easily into a professional H-alpha telescope! For telescopes up to 80mm aperture, you do not need any further accessories: The SunDancer II already includes an achromatic (!) 3x telecentric with T-2 connection; the entire SunDancer is simply plugged between star diagonal and eyepiece and connected to a power source. It then automatically heats up to the optimum operating temperature. No readjustment is necessary even during long observation sessions. Finetuning the transmission line e.g. to adapt to different telescope systems is possible via the control box; the micrometer screw can be used to quickly shift the transmission line into the blue wing of the H-alpha line to compensate for the Doppler effect during fast H-alpha events on the sun

An additional D-ERF energy protection filter in front of the telescope is necessary only on telescopes with more than 80mm aperture; alternatively, the telescope can also be stopped down to 80mm with an optional diaphragm in front of the lens.

Power is supplied either via the included power supply or via an optional PowerTank. A detailed description of the possible applications and the requirements for the telescope can be found in the operating instructions under the "Downloads" tab.

Solar disk and prominences

The H-alpha filter has a half width of 0.6 +/- 0.1Å on telescopes with f/10. The telecentric (corresponds to the soon separately available TZ3 #1363070, but additionally with integrated 12nm block filter) extends the focal length of the telescope by a factor of three, so that on telescopes with f/10 the ideal focal ratio of f/30 for H-alpha is achieved. The SunDancer II is recommended for telescopes up to about f/8 and is well usable up to about f/6.5; on faster telescopes the half-width increases. The half-width was chosen in such a way that both prominences and the solar surface are nicely displayed at the same time.

Visual, photographic and binocular

The complete solar disk can be seen in telescopes up to about 600mm focal length. A T-2 thread under the eyepiece clamp also allows the adaptation of larger cameras. The SunDancer II is also compatible with the SolarSpectrum Research Grade 0.4x Telecompressor 2" (#2459260, € 345,-) , so that the entire sun can then be imaged even on an MFT sensor with telescopes of up to 600mm focal length.

Particularly appealing is the space-saving connection of a bino-viewer via the T-2 thread. In most cases, a glass path corrector is not necessary: the telecentric provides a parallel beam of light and at the same time shortens the necessary back focus.


The dielectric coating of the block filter (instead of the usual silver coating) and airtight storage of the SolarSpectrum Etalon filter in oil prevent the ageing processes of simpler filter designs. With proper treatment, the SunDancer II will retain its performance for many years. Please note that the filter - just like any H-alpha filter with Fabry-Pérot Etalon - must be protected from frost. It must not be stored below 0°C, as otherwise the oil will become sulky and push the optical elements apart, damaging the filter. Thermal insulation is necessary for use at lower temperatures.

SKU (#) 1363056
USAGE Visual solar observation and solar photography
HBW (HALFBANDWIDTH) 0.6 +/- 0.1 Angstrom
OPTIONAL ACCESSORIES Additional D-ERF only necessary with telescopes over 80mm
INCLUDED ACCESSORIES SunDancer II H-alpha filter, control box for temperature control, 12V power supply, sturdy hard case, Baader Utility Bag, detailed manual

Product Info

Brand Baader
Product Code 1363056
Delivery Weight Package