8
© Baader Planetarium GmbH | 2021
9
Manual: SunDancer II
temperature of the filter must be increased (see section
"Calibrating the Filter"), and the half-width increases
to more than 1 Å instead of the usual 0.6±0.1Å, as
already mentioned. This will cause many details on the
solar surface to disappear. For best results, it is better
to stop down the telescope in front of the lens to f/8
or slower than to use the filter with artificially enlarged
half-width. For this purpose we offer the stepless ad-
justable iris diaphragm 13-113 mm
(# 2459300)
. It has
elaborately white-painted blades so that no unnecessa-
ry heat is generated close to the lens. A simple, white-
painted baffle can easily be made yourself and attached
with Velcro in front of the D-ERF, for example, as in the
picture on the right.
Telescopes with a slower focal ratio can also be used,
but due to the longer focal length they quickly reach minimum magnifications that can
rarely be used during the day (due to air turbulence or exit pupil).
The telecentric of the SunDancer II also contains a blocking filter. It shimmers golden
when you look into the SunDancer from the telescope side. This block filter is absolu-
tely necessary to protect the actual H-alpha filter from solar radiation.
Although the telecentric system can be seperated from the etalon, the SunDancer II
must only be used in combination with the included telecentric system!
The modular design of the SunDancer II allows it to be used with other telecentrics
(and an additional blocking filter!).
Attention:
Using it with a telecentric without
this additional block filter would destroy the
etalon just as much as using it without D-ERF
on larger telescopes than 80 mm.
The 3x telecentric
(# 1363070)
is also
available without blocking filter, e.g. for use on
other H-alpha filters. The blocking filter is not
available separately.
A 4x telecentric with integrated blocking
filter is planned in the long term, the existing
blocking filter of the TZ-3 must then be moun-
ted in the TZ-4.
A D-ERF can be stopped down with a
simple baffle
The 3x telecentric system
(# 1363070)
without blo-
cking filter is also available
separately.
The 3x telecentric system
with integrated blocking
filter is only available com-
bined with the SunDancer II.
Eyepieces
In principle, you can use any eyepiece that provides a
sharp, high-contrast image. Special H-alpha eyepieces are
mainly corrected for the red part of the spectrum and may
not provide a similarly sharp image as in H-alpha when ob-
serving white light. Long focal length eyepieces still provide
a bright image even at the ideal focal ratio of f/30 for an
H-alpha filter and avoid to high magnifications. Exceeding
the highest useful magnification would cause a sensitive
loss of sharpness.
Note:
Because of the telecentric, the system is very tole-
rant concerning working distances. Even a bino-viewer can
be used without an additional glass path corrector.
1
You can use any 1¼" eyepiece via the focusable 1¼"
eyepiece clamp
(# 2458125)
included in the scope of delive-
ry. We recommend eyecups with a foldable side light shade.
An observation cloth that is white on the outside and black
on the inside also helps to suppress stray light and increase
contrast.
The telecentric allows you to reach high magnifications
very quickly and end up in over-magnification very quickly
with common eyepieces. The blocking filter in front of of the
telecentric has a diameter of 12 mm. The etalon itself has
a diameter of 23 mm with a 19 mm baffle on the eyepiece-
side.
Long focal length 1¼" eyepieces have field stop diame-
ters up to about 28 mm. This field stop diameter covers the
available image circle of the SunDancer II.
The use of 2" eyepieces is nevertheless profitable, as it
allows lower magnifications and thus a brighter image, plus
often a more comfortable viewing behaviour and an even
slightly larger field of view. You have two options for using 2"
eyepieces:
2
Replace the 1¼" eyepiece clamp
(# 2458125)
included
in the scope of delivery with the optional Baader 2" Click-
Lock T-2 (M42i × 0.75) clamp
(# 2956242)
. For 1¼" eyepie-
ces, you will then need an adapter such as the Baader 2" to
1¼" ClickLock reducer
(# 2956214)
.
3
Screw the optional Expanding Ring T-2f / M48m
(# 2458110)
into the 2" filter thread of the nosepiece of your
eyepiece. This way you have a "theft-proof" connection,
which is especially useful for public use when the eyepiece
is rarely changed.
1
2
3
The SunDancer II consists of two parts (plus the 1¼" eyepiece clamp). On the left is the actual H-alpha filter, i.e. the
etalon with the heating element and the micrometer screw. To the right, in the 3x telecentric system, the integrated
block filter can be seen in the entrance opening.
