Baader SunDancer II H-alpha Filter

The Baader SunDancer II H-alpha Filter (with heated H-alpha Etalon from SolarSpectrum) transforms an existing telescope quickly and easily into a high performing H-alpha telescope.

Baader SunDancer II H-alpha FilterFor telescopes up to 80mm aperture, you do not need any further accessories as the Baader SunDancer II H-alpha Filter 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 to adapt to different telescope systems, for example, is made 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 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.

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 Baader 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.

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″, 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 aging processes of simpler filter designs. With proper treatment, the SunDancer II will retain its performance for many years. As the Baader team note’s “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.”

Features of the Baader SunDancer II H-alpha Filter include:

– H-alpha filter with a half-width (FWHM) of 0.6±0.1Å at an effective focal ratio of f/30;

shows prominences and solar surface details.

– Integrated 3x telecentric system with 2nm Half-Bandwidth (FWHM) blocking filter. The TZ3-system is suitable up to 35 mm field of view without vignetting. Optimal for telescopes with f/10, recommended up to about f/8 and usable up to about f/6.5. On optics faster than f/10, the FWHM (Full Width at Half Maximum) increases.

– Easy change of the transmission line by turning the micrometer screw to observe fast solar events in the blue wing of the H-alpha line (Doppler shift)

– Resistant to ageing: The dielectric coating of the blocking filter (instead of the usual silver coating) and the airtight storage of the Etalon filter in oil prevent the ageing processes of simpler filter designs. With proper treatment, the filter will retain its performance for many years.

– 25 mm Etalon from SolarSpectrum – with 23 mm aperture behind 19 mm aperture baffle.

– Removable focusable 1.25″ eyepiece clamp and T-2 thread for connecting cameras

– On telescopes with up to 80 mm aperture and a focal ratio of f/8 or slower, Baader SunDancer II can be operated without an additional D-ERF energy protection filter in front of the objective – tested for 10 hours on the Baader-Apo 95 at f/6.1.

– Electrical temperature control: the filter automatically heats up to its optimum operating temperature as soon as it is connected to the power supply

– Low power consumption: Via the supplied main adapter or, in mobile use, via an optional rechargeable battery pack.

– Wide operating temperature range: -10 to +40° C; storage temperature not below 0° C.

The Baader SunDancer II H-alpha Filter system comes with the SunDancer II H-alpha-filter unit comprising the blocking filter, 3x telecentric system and focusing eyepiece holder; temperature control box (hand control); power supply (with international adapters); carrying case and Baader Utility Bag.

You can learn more here.

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