SunDancer II H-alpha Filter

H-alpha observing made easy

Baader SunDancer II on Triband-SCT Multi-Purpose Telescope

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 separately available TZ-3S Telecentric System T-2 for SunDancer II and more (#1363070 , € 365,- ) , 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 Telecompressor 2" H-alpha 0.4x – Research Grade, for Solar Spectrum (#2459260 , € 366,- ) , 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.

Robust

The dielectric coating of the block filter (instead of the usual silver coating) and airtight storage of the SolarSpectrum Etalon filter in oil makes the Sun dancer robust. 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.