10
Manual: SolarSpectrum H-alpha-Filter and Baader Planetarium Telecentric Systems
The Telecentric Systems
The clear aperture of the SunDancer TZ-3S
# 1363070
(27,5 mm, left) and TZ-4S
# 1363080
(36 mm, right)
About Magnification and Working Distance
of Telecentric Systems
Unlike a barlow lens, behind which the beam of light widens, a telecentric provides
a parallel beam of light. This is necessary for the proper functioning of an H-alpha
filter (which requires at least f/30 and a parallel beam of light). The second advan-
tage of this design is that the distance between camera/eyepiece and telecentric
can also be significantly changed without noticeably affecting
the image.
In practice, you don't have to match this distance perfectly.
The 2" Research Grade TZ-3
# 2459257
is
calculated for a working distance of 250
mm ±10 mm, so that it also works perfectly
with a bino-viewer. A greater distance is no
problem.
Please note: In principle, you can also use
an eyepiece very close behind the telecen-
tric or the H-alpha filter mounted behind
it. Then, however, you will not only see the
image of the sun, but also the sealent and
other structures within the naturally grown
etalon filter, which have no influence on the
final image at the correct working distance,
but can be visible as streaks if the distance
is too short.
Unlike a barlow lens, you cannot change
the image scale by changing the working distance. For a higher magnification (as
far as it fits the pixel size of the camera), we recommend the Telecentric System
TZ-4
# 2459256
(230 mm working distance) or the SunDancer TZ-4S
# 1363080
(120
mm working distance) instead of an additional barlow lens. Unlike standard Barlow
lenses, these telecentrics are also optimised for H-alpha observation.
Please note that the 2" Research
Grade TZ-3
# 2459257
and the tele-
centric systems TZ-4
# 2459256
and
TZ-2
# 2459255
(discontinued) are not
barlow lenses and are optimised for
a Strehl of 99% at the H-alpha line
of 656.3 nm, but not for other wave-
lengths.
The SunDancer telecentrics TZ-3S
# 1363070
and TZ-4S
# 1363080
are
achromatic systems that can also be
used as barlow lenses.
SunDancer TZ-4S
# 1363080
(left)
and TZ-4
# 2459256
(right)
