18
© Baader Planetarium GmbH | 2021
19
Manual: SunDancer II
glass and the sensor during H-alpha photogra-
phy. This is a problem of the camera and not
of the filter; the fringe patterns rotate with you
when you turn the camera. In this case, it can
help to tilt the camera or make a flat, but this is
not trivial with such a narrow band filter. Ano-
ther possibility might be to tilt the filter. Within
certain limits, the filter tilt can be compensated
again by the temperature control, so that the H-
alpha line is hit again even with a tilted filter.
You can use a tilting unit like our Baader M68-Tilter
# 2458170
to tilt the camera very
precisely behind the filter and remove the interference pattern.
However, this problem does not occur with all cameras, so there is no patent remedy
for it. We have had good experience with the monochrome cameras made by QHY.
DSLR and CCD Cameras
If you unscrew the focusable
eyepiece clamp, you can connect
astronomical cameras with T-2
threads as well as DSLR and mir-
rorless system cameras via the T-2
thread (M42 × 0.75); you can find
suitable T-adapters for the respec-
tive camera bayonet at
baader-
planetarium .com
.
Via the Expanding Ring T-2f /
M48m
(# 2458110)
, you can also
use M48 camera adapters and
Baader Planetarium's Wide-T rings
to avoid mechanical vignetting on
full-frame cameras.
Here, too, you should observe the ideal working distance of 65 mm. An SLR camera
with a standard T-ring has a flange focal distance of 55 mm; with the T-2 internal th-
read ring 10 mm
(# 2958110)
and the T-2 reversing ring adapter T-2 to T-2
(# 1508025)
,
you will achieve the ideal distance of 65 mm; you will also achieve good results with
the T-2 quick-change system
(# 2456322)
with 15 mm construction length. Mirrorless
system cameras and astronomical cameras have a shorter flange focal length and
require different extension tubes, depending on the model.
Tip:
In principle, black-and-white cameras are better suited for H-alpha solar photo-
graphy, because the Bayer matrix of a colour camera means that three quarters of the
pixels cannot perceive red light at all.
Tip:
The surface of the sun and the prominences have very different brightnesses and
normally cannot both be exposed correctly in one shot - the solar disk is much brigh-
ter. If the green channel of your colour camera is also slightly sensitive to red light, you
can try to expose on the prominences and use only the weaker green channel for the
solar disk.
A DSLR with a standard T-ring still needs a 10mm T-2 extension.
A standard T-ring has an overall length of 55 mm - here using the
example of a mirrorless Micro Fourthirds camera with the Micro
Fourthirds T-ring
# 2408330
(with 19 mm extension).
# 2408330
# 2958110 + # 1508025
Photography
In total, you have three options for connecting a camera to the SunDancer II. For the
best imaging quality, you should pay attention to the working distance of 65 mm, alt-
hough the system also works well at other distances. A deviation from the ideal working
distance will affect the magnification and image quality, although the system has pro-
ven to be quite docile. The working distance is also long enough for use with a DSLR.
1¼" Video Modules/Planetary Cameras
A modern imaging camera like the ones used for pla-
netary photography is the first choice for obtaining
high-resolution images of details on the solar surface
or in the photosphere. To maintain the optimal wor-
king distance, you can place T-2 extension sleeves
between the eyepiece clamp of the SunDancer II and
the actual filter unit. Simply unscrew the eyepiece
clamp to expose the T-2 thread.
The focusable eyepiece clamp has an overall length
of 29 - 35.5 mm. Which extension sleeves you need
depends on the sensor position of the camera – on
some models the sensor is in the 1¼" socket, on
others behind it. On
baader-planetarium .com
you
will find various extension sleeves, including among
others:
• T-2 extension tube 40 mm
# 1508153
• T-2 extension tube 15 mm
# 1508154
• T-2 extension tube 7,5 mm
# 1508155
• VariLock 29, lockable T-2 ExtensionTube
20-29 mm with spanner tool
# 2956929
If possible, use a stop ring to reproduce the positi-
on of the camera over and over again. If no stop ring
is included with your camera, you can use the 1¼"
stop ring
(# 1905131)
for this purpose. It can also be
used to make the camera parfocal with an eyepiece, if necessary in conjunction with
the 1¼" extension tube with 1¼" filter thread
on both sides
(# 1905130)
.
Monochrome cameras are more suitable
because they are more sensitive to light and
allow shorter exposure times. In addition, all
pixels are used in this way; in colour cameras
with an RGGB matrix, only a quarter of the
pixels are sensitive at all to the deep red H-
alpha light.
With some monochrome cameras, interfe-
rence patterns occur between the protective
SunDancer II with Baader M68-Tilter and adapters
# 1508153
A planetary camera with 1¼" plug-in slee-
ve. A 40 mm T-2 extension sleeve provides
the ideal working distance of 65 mm.
Interference pattern of a monochrome camera.
