6Manual: Baader Planetarium TriBand-SCT
lter such as the Baader RGB R lter 2" # 2961603R or the H-alpha bandpass lter 20
nm 2" # 2961853. This way you observe in the part of the spectrum that is least dis-
turbed by air turbulence. The 7.5 nm Solar Continuum Filter # 2961581, which comes
with our Herschel prism, was designed for 540 nm, as most refractors are optimised
for this wavelength – with a catadioptric telescope, this restriction is removed and you
can use the red part of the spectrum, where there are less air turbulences. The O-III 2"
Super-G lter (9 nm) # 2961551 with passband at 502 nm also delivers similarly good
results as the Solar Continuum lter.
At the other end of the spectrum, in the near UV, the Baader Calcium GEN-II 1¼"
# 2961590 can be combined with the Herschel wedge to observe the sun in the region
of the calcium K-lines. This lter may only be used photographically and absolutely
requires a Herschel prism or one of the following Baader Digital Solar Filters as a pre-
lter:
• TriBand 8": Baader Digital Solar Filter (BDSF) OD 3.8 – 200 mm # 2459376
• TriBand 9¼": Baader Digital Solar Filter (BDSF) OD 3.8 – 240 mm # 2459377
• TriBand 11": Baader Digital Solar Filter (BDSF) OD 3.8 – 280 mm # 2459378
Using a H-alpha-Filter
Depending on the model, an H-alpha lter can either be screwed directly to the
telescope's 2"-thread, or it is connected via the 2" ClickLock clamp # 2956220 if it
is equipped with a 2" nose piece. Especially with the large SolarSpectrum lters, we
recommend the sturdy screw connection to avoid tilting.
On the TriBand telescopes, you do not need an additional energy rejecting lter;
otherwise, the operating instructions for your H-alpha lter apply without restriction.
Both the SolarSpectrum lters and the Baader SunDancer II ideally require a focal
ratio of f/30 to provide the best H-alpha contrast. Therefore, they need a 3x telecentric
system, which increases the focal length of the telescope to 6096 mm (TriBand C8),
7050 mm (TriBand C9¼) or 8400 mm (TriBand C11). Even with a 40 mm eyepiece, you
can thus achieve a very high minimum magnication of 150x to 210x with an exit pupil
of 1.3 mm in each case and are close to the range of maximum magnication that can
be used during the day. By using a SolarSpectrum telecompressor, you can reduce
the magnication again behind the H-alpha lter. This is especially useful when using
modern CMOS cameras, whose small pixels harmonise better with faster focal ratios.
The following telecompressors are available for photography:
• SolarSpectrum Research Grade H-alpha 0.4x Telecompressor 2" # 2459260
• SolarSpectrum 0.7x Telecompressor 2" # 2459259
Resulting focal length with 3x telecentric system and telecompressor:
Telecompressor TriBand 8" TriBand 9¼" TriBand 11"
0,4x Research Grade 2438 mm 2820 mm 3360 mm
0,7x 4267 mm 4935 mm 5880 mm
Please note that the eld of view is limited by the diameter of the H-alpha lter which
is located in front of the reducer.
