The Baader SunDancer II H-alpha filter transforms any refractor or SCT into a powerful solar telescope for high resolution visual observation and photography. With a half-bandwidth of 0.6 ± 0.1 Å and a heated etalon from SolarSpectrum, the SunDancer II provides exceptional views of both prominences and chromosphere at the same time.
The SunDancer II includes an achromatic 3x telecentric barlow with a T2 connection, allowing f/10 telescopes to achieve the perfect f/30 ratio for H-alpha observation. Telescopes with focal ratios as fast as f/8 can be used with excellent results, and telescopes up to f/6.5 are still usable. When paired with a telescope with a focal length up to 600mm, the full solar disc along with prominences are visible.
The optional TZ-4S 4x telecentric is available for telescopes faster than f/8 to achieve the desired focal ratio. These telecentrics are not permanently installed on the SunDancer and can be swapped out for different telescopes.
Unlike other H-alpha filters which are designed with smaller telescopes in mind and thus have limits on achievable resolution, the SunDancer II provides exceptional resolution, down to 0.7 arc-seconds with the default telecentric and even more with the TZ-4S.
Installation is simple - the entire SunDancer is 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. The T2 thread allows connection of large imaging sensors as well as binoviewers, thanks to the low profile and telecentric design.
With the addition of the Baader M68 Tilter (sold separately), the appearance of Newton's Rings during solar imaging can be easily tuned out.
Fast finetuning the transmission line e.g. to adapt to different telescope systems is possible via the control box; the micrometre 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. You don't need to wait for the system to re-adjust its temperature between tuning.
The SunDancer's blocking filter features a hard dielectric coating and the SolarSpectrum etalon is sealed in an air-tight oil cavity. This makes the assembly incredibly resistant to aging and does not have to be re-coated anywhere near as much as h-alpha filters from other manufacturers.
Note: For telescopes with an aperture greater than 80mm, an external front-mounted energy rejection filter is required. The Baader D-ERF dielectric energy rejection filters are recommended. Telescopes 80mm and smaller do not need an additional rejection filter.
The image quality of standalone H-alpha filters depends on the quality of the mirror diagonal they are paired with. We recommend purchasing the highest quality diagonal you can afford, such as Baader's BBHS-coated mirror diagonal.
||H-alpha solar observation and photography
||0.6 ± 0.1 Å @ 656.3 nm
||19 mm (23 mm without eye-side baffle)
|Blocking filter diameter
||2 nm, 12 mm free aperture
|Etalon||25 mm Fabry-Pérot Etalon, tiltable & heated|
|Connection telescope side
||1.25" barrel, 2" barrel
|Connection eyepiece side
||1.25" clamp, M42 x 0.75 (T2) male thread
||-10 to +40° C; storage temperature not below 0° C
|Ideal back focus for imaging||65 mm from base of T2 thread|