Baader Planetarium SUNDANCER II User manual

BAADER PLANETARIUM
ZurSternwarte4
•D - 8 2 2 9 1 M a m m e n d o r f •Te l . + 4 9 ( 0 ) 8 1 4 5 / 8 0 8 9 - 0 •F a x + 4 9 ( 0 ) 8 1 4 5 / 8 0 8 9 - 1 0 5
www.baader-planetarium.com • [e-mail] • www.celestron.de
G
M
B
H
Manual
and Application Tips
Thank you for your purchase of the SunDancer II H-alpha lter! It is a high quality product
for solar observation. When observing the sun, always exercise due caution and follow the
safety instructions.
For best results, we recommend that you spend a few minutes reading this manual before
using the SunDancer II.
– EN ver. 08/2023 –

2Manual: SunDancer II
Table of Content
SunDancer II H-Alpha-Filter ............................................ 3
All in one! ........................................................... 4
Scope of Delivery .................................................... 5
Preparations......................................................... 6
Choosing a Dielectric Energy Rejection Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Usage without an Energy Rejection Filter ........................................7
The Telecentric System and Thoughts about the Telescope ................... 7
Eyepieces.......................................................... 9
ChoosingaStarDiagonal ............................................ 10
Power Supply...................................................... 10
Observing with the SunDancer II ....................................... 11
ThepartsoftheSunDancerII......................................... 11
Connectingtothetelescope.......................................... 11
The Functions of the Temperature Control Box............................ 12
Changing the Operation Temperature ..........................................13
UsingaNeutralDensityFilter ......................................... 13
Using a Telecompressor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
UsingaBino-Viewer ................................................ 15
Calibrating the Filter and Settings of the Temperature Control Box .......... 16
Setting the Temperature.............................................. 16
Calibrating the Filter................................................. 17
Tilting the Filter ...........................................................17
Troubleshooting ...........................................................17
Photography ....................................................... 18
1¼"VideoModules/PlanetaryCameras................................. 18
DSLR and CCD Cameras............................................. 19
Telecompressor.................................................... 20
Afocal Photography ................................................. 20
Storage and Maintenance ............................................ 21
Safety information ................................................... 21
Technical Data ...................................................... 21
Don't miss anything – The Baader-Planetarium Newsletter . . . . . . . . . . . . . . . . . . 22

© Baader Planetarium GmbH | 2021 3
Front Lens
Mirror Star
Diagonal
H-alpha Blocking
Filter (Ø12mm)
Achromatic 3x
Telecentric System
Etalon (Ø25mm)
tiltable, heated
Bae (Ø19mm)
Micrometer Screw
Research Grade
H-alpha 0.4x
Telecompressor 2"
Focusing
Eyepiece Holder
(# 2458125)
Eyepiece
Eyecup with
Folding Wing
D-ERF
(for apertures > 80mm)
Aperture Bae
or Diaphragm
Schematic Setup of an H-alpha-Telescope with
SunDancer II Filter
A D-ERF filter is necessary on telescopes with more
than 80 mm aperture. With an optional aperture
baffle or iris diaphragm in front of the front lense, the
telescope can be stopped down to the ideal focal ratio
of f/10.
Red: Components of the SunDancer II.
Yellow: Optional accessories.
Quickstart
The SunDancer II is simply plugged between the star diagonal and eyepiece. Connect
the SunDancer II to the control box (cables and ) and the control box to a power
source. The lter automatically heats up to the preset operating temperature; as soon
as the display no longer shows a change in temperature, the operating temperature
has been reached.
Use the micrometer screw or the arrow keys on the control box until you see the H-
alpha line and to ne-tune the SunDancer to your telescope.
An energy protection filter is not necessary for telescopes up to 80mm aperture.
For larger apertures, a D-ERF is mandatory.
The parts of the SunDancer II
1. SunDancer II
2. Micrometer screw for quick netuning of the Etalon
for observing the blue wing of the H-alpha, should be
set counterclockwise
3. Three locking screws for the eyepiece
4. Locking screw for ne focuser
5. Connection cable to hand control
6. Hand control (temperature control box)
7. Connection cable to SunDancer II
8. Connection port for 12V power cable (on the back;
power supply is not shown)
1
2
3
4
5
6
7
8

4Manual: SunDancer II
SunDancer II H-Alpha-Filter
Congratulations on your purchase of the SunDancer II, a compact heated H-alpha lter
that combines a 3x telecentric system, ablocking lter and an H-alpha lter in a single
housing. It has been designed with safety and ease of use in mind, combined with
an extremely age-resistant construction and a high-quality lter. The most important
features are:
• H-alpha lter with a half-width (FWHM) of 0.6±0.1Å at an effective focal ratio of f/30;
shows prominences and solar surface details.
• Integrated 3x telecentric system with 12 mm block lter. The TZ3-system is suitable
up to 35 mm eld of view without vignetting. Optimal for telescopes with f/10,
recommended up to about f/8 and usable up to about f/6.5. On optics faster than
f/10, the FWHM (Full Width at Half Maximum) increases. Thus, for faster telescopes
with approximately f/7.5, there is the SunDancer II Telecentric System TZ-4S
#1363080 avaiable, which increases the focal length by factor 4 and in which the
blocking lter of the SunDancer II can be installed.
• Easy change of the transmission line by turning the micrometer screw to observe
fast solar events in the blue wing of the H-alpha line (Doppler shift)
• Resistant to ageing: The dielectric coating of the blocking lter (instead of the usual
silver coating) and the airtight storage of the Etalon lter in oil prevent the ageing
processes of simpler lter designs. With proper treatment, the lter will retain its
performance for many years
• 25 mm Etalon with 23 mm aperture behind 19 mm aperture bafe
• Removable focusable 1¼" eyepiece clamp and T-2 thread for connecting cameras
• On telescopes with up to 80 mm aperture and a focal ratio of f/8 or slower, it can be
operated without an additional D-ERF energy protection lter in front of the objecti-
ve – tested for 10 hours on the Baader-Apo 95 at f/6.1
• Electrical temperature control: the lter automatically heats up to its optimum ope-
rating temperature as soon as it is connected to the power supply
• Low power consumption: Via the supplied mains adapter or, in mobile use, via an
optional rechargeable battery pack
• Wide operating temperature range: -10 to +40° C; storage temperature not below
0° C

© Baader Planetarium GmbH | 2021 5
All in one!
An H-alpha lter system consists of several elements:
• The etalon filter is the actual H-alpha lter. As an interference lter, it cancels out all
wavelengths except the H-alpha line. Its lter effect depends on the lter thickness
and is automatically controlled by the temperature control.
• The telecentric system provides the parallel beam of light path which is necessary
for the etalon to function properly. A Barlow lens or even a telescope with f/30 pro-
vides the necessary focal ratio, but not the necessary parallel beam of light.
• The blocking filter reects the
incident sunlight just in front of
the etalon and the telecentric. This
protects the etalon from excessive
heat. In addition, an etalon also
transmits wavelengths that are
many times the desired transmissi-
on line; these are also blocked by
the blocking lter.
• The D-ERF energy rejection filter
is mounted in front of the telescope
and protects the lter system from
unnecessary solar energy by al-
lowing only red light to pass.
With the SunDancer II, the etalon,
telecentric system and blocking lter form one unit; on telescopes with a maximum
aperture of up to 80 mm, the energy protection lter can be omitted if necessary (see
chapter "Choosing a Dielectric Energie Rejection Filter"). The result: easier handling
and lower entry costs!
Front Lens
Mirror Star
Diagonal
H-alpha Blocking
Filter (Ø12mm)
Achromatic 3x
Telecentric System
Etalon (Ø25mm)
tiltable, heated
Bae (Ø19mm)
Micrometer Screw
Research Grade
H-alpha 0.4x
Telecompressor 2"
Focusing
Eyepiece Holder
(# 2458125)
Eyepiece
Eyecup with
Folding Wing
D-ERF
(for apertures > 80mm)
Aperture Bae
or Diaphragm
Schematic Structure of A H-alpha-Telescope with
SunDancer II Filter
A D-ERF filter is only necessary on telescopes with
more than 80 mm aperture. With an optional aperture
baffle or iris diaphragm, the telescope can be stopped
down to the ideal focal ratio of f/10.
Red: Components of the SunDancer II.
Yellow: Optional accessories.
SunDancer II at a telescope with mirror star diagonal.
Hand control and power supply are stored in the yellow bag.

6Manual: SunDancer II
1
23
4
5
Scope of Delivery
of the SunDancer II
1. SunDancer II H-alpha-lter unit comprising the blocking lter, 3x telecentric system
and focusing eyepiece holder #2458125
2. Temperature control box (hand control)
3. Power supply (with international adapters)
4. Carrying case
5. Baader Utility Bag #2954201

© Baader Planetarium GmbH | 2021 7
Storage and Maintenance
As long as you handle the lter with care like any other precision optical instrument
and use the dust caps when not in use, it requires no special care. An occasional
cleaning of the lenses of the telecentric system is all that is needed – and all the less
often if the optics are stored carefully with the dust caps on.
The H-alpha-Filter must not be cleaned mechanically!
For cleaning, you must only use a pair of bellows – never use compressed air from
a can! You must never attempt to clean the H-alpha-lter mechanically by swiping or
rubbing!
Caution: The lter must not be stored permanently below +4° C,
otherwise the lter stack will freeze out and be irreparably damaged.
Store it dry and dust-free at room temperature.
The lter should be used at an ambient temperature of 0 to +40° C;
at lower temperatures it must be additionally thermally insulated so
as not to overload the heating.
Safety information
Finally, we would like to urge you once again to observe all safety precautions when
observing the sun. This includes:
• Never leave the telescope unattended
• Always cover all viewnders and other optics that are not in use.
• Ensure that the energy protection lter is held securely in place.
• Set the tracking of the mount to the speed of the sun instead of the star.
• Remember sunscreen for yourself when observing for long periods.
Technical Data
• Operating temperature: 0 to +40° (below 0° only with insulation).
• Storage temperature: +4 to +50°C, ideally at room temperature. Protect from frost!
• FWHM: 0.6±0.1 Ångström, shows chromosphere and prominences
• 3x telecentric with built-in block lter, optimal for refractors up to f/10, recommen-
ded up to f/8 and usable up to f/6.5
• Usable up to 80 mm aperture without additional D-ERF energy lter
• Diameter of the blocking lter: 12 mm
• Diameter of the etalon: 25 mm, with 23 mm free aperture and 19 mm eye-side bafe
• Ideal working distance for photography: 65 mm from the base of the T-2 thread
• Connection on telescope side: 2" and 1¼" plug-in sleeve
• Connection on eyepiece side: 1¼" with ne focusing; T-2
• With telescopes up to approx. 600 mm focal length, the entire solar disk is visible

8Manual: SunDancer II
Preparations
Choosing a Dielectric Energy Rejection Filter
A Dielectric Energy Reection Filter
(D-ERF) is used to protect the actual
H-alpha lter from the intense solar
energy. In principle, it is a plano-op-
tically polished lter that only allows
red light in the vicinity of the H-alpha
line to pass and thus ensures that
the actual H-alpha lter does not
become too hot. It does not have to
be as narrow-banded as the actual
H-alpha lter; however, the same
demands are made on its surface
accuracy as on the telescope
objective. A white-light solar lter
(e.g. made of AstroSolar lm) cannot be used for this purpose because it also darkens
the H-alpha line, which is weaker than the rest of the solar radiation.
On all telescopes with more than 80 mm aperture as well as on telescopes with
secondary mirrors (e.g. Newtons or Schmidt-Cassegrains), a D-ERF protective
filter (not included in the scope of delivery) is absolutely necessary for long-term
observations (longer than a maximum of five minutes). A selection of suitable lters
can be found at baader-planetarium.com/derf; a suitable 3D-printed lens mount can be
created by yourself or by various service providers.
These D-ERF lters also serve as UV and IR blocking lters and reect the incident
sunlight instead of absorbing it. If you want to use a smaller D-ERF lter diameter on
an obstructed telescope to simultaneously stop it down to a more favourable focal
ratio, choose the diameter of the D-ERF in such a way that it sits off-centre next to the
secondary mirror in the optical path. Otherwise you will lose aperture if the secondary
mirror sits behind the D-ERF. Do not try to put several smaller D-ERFs next to each
other in order to use more aperture despite having a secondary mirror – this also does
not give satisfactory results. Please note that a D-ERF must be tilted by approximately
3° when it is mounted off-axis.
A suitable mount specically for your telescope can be made by us only if you
purchase a complete system consisting of D-ERF and H-alpha lter. However, this is
relatively expensive due to the design and production time. For a quotation we need
the diameter of the mount with an accuracy of 1/10 mm. Instructions on how to const-
ruct your own mount can be found at baader-planetarium.com/derf.
The lter should be mounted as close as possible to the front of the lens so that no
warm layers of air can accumulate between the lens and the lter and impair the image
quality. Always make sure that the lter is rmly seated to avoid it dropping from the
telescope!
Energy protection filters up to 180 mm aperture can
individually made for your telescope, if necessary also with adjus-
table iris diaphragm or fixed aperture diaphragm.

© Baader Planetarium GmbH | 2021 9
Usage without an Energy Rejection Filter
With telescopes with an aperture of
80mm or less and a focal ratio of f/8 or
slower, the SunDancer II can be used
without an energy protection lter (ERF)
in front of the telescope objective. This
makes it a particularly inexpensive and
safe system for H-alpha solar observation,
as you only need one accessory and do
not run the risk of forgetting the D-ERF
front lter.
However, only the observer behind the
eyepiece is safe. When using the telescope
without D-ERF, the tightly bundled light beam is rst reected inside the tube at the
front block lter before the telecentrics and is then deected out of the telescope
towards the front again. Therefor when using the telescope without a D-ERF, make
sure that no one can look into the telescope from the front. The risk is highest with
low-mounted, short-focal length telescopes pointed at a low-elevation sun. The photo
shows the glistening bright reected light beam in front of an 80 mm objective.
You can also use D-ERF lters on smaller telescopes, as they protect the inside of the
tube from the heat of the sun. This has no inuence on the function of the SunDancer II,
but it may affect the tube entrance and thus the possible maximum magnication.
The Telecentric System and Thoughts about the Telescope
The SunDancer II has a built-in 3x telecentric system with an integrated blocking lter.
Similar to a Barlow lens, the telecentric system triples the focal length and effective
focal ratio of the telescope, but unlike a Barlow, it also ensures a parallel beam path.
There is no way that a parallel light beam would result without a telecentric even in a
native f/30-telescope or in a telescope would be brought to this focal ratio with a Bar-
low! A slightly conical beam path with f/30 would give a weaker contrast with an etalon
with 0.5 Å FWHM – comparabable to a lter 0.7 Å FWHM or less. Only a telecentric
system delivers this perfectly parallel beam path, which is essential for the unrestricted
function of an etalon.
The SunDancer II is optimized for an effective focal ratio of f/30, i.e. for telescopes
working natively with f/10. It can be operated on telescopes up to about f/8 (giving an
effective focal ratio of f/24) without too much increase in half-width.
The lter can also be used on faster telescopes with the restrictions mentioned abo-
ve. However, with an effective focal ratio of f/20 or faster (i.e. on f/6.6 telescopes), it is
mandatory to mount a Baader D-ERF lter in front of the lens. In addition, the target
The concentrated, reflected solar radiation in front of an
80 mm telescope without D-ERF in front of the objective.
Without a D-ERF, never look
into the telescope from the front!
Baader Telezentrische Linsensysteme (TZS) f¸r die
Sonnenbeobachtung mit schmalbandigen H- Filtern
Zur erfolgreichen Sonnenbeobachtung mit schmalbandigen Linienfiltern (Halbwertbreiten unter 1
Angstrˆm) der Marken "Solar Spectrum" und "Day Star" ist ein Teleskop mit einem ÷ffnungsverh‰ltnis
von mindestens f/30 die Voraussetzung. Dieses ÷ffnungsverh‰ltnis l‰sst sich entweder durch Abblen-
den der Objektivˆffnung ñoder vorzugsweise durch Brennweitenverl‰ngerung mit einem "Telezentri-
schen System" (TZS) ñerzielen. Telezentrische Systeme sind nicht mit Barlowlinsen gleichzu-
setzen (siehe Grafiken)! Nur mit einem TZS entsteht ein paralleles Strahlenb¸ndel, nur damit ist eine
gleichm‰flige Darstellung der chromosph‰rischen Strukturen ¸ber das gesamte Bildfeld des Tele-
skops gew‰hrleistet.
Generell sind nur Refraktoren und katadioptrische Teleskopsysteme mit Hauptspiegelfokussierung
(z.B. Schmidt-Cassegrain Teleskope) zur H-alpha Sonnenbeobachtung geeignet, bei den meisten an-
deren Teleskopsystemen (Newton) steht bauartbedingt der erforderliche Fokussierweg zum Anschluss
des Zubehˆrs zur H- Beobachtung nicht zur Verf¸gung.
Einsatz der Telezentrischen Linsensysteme
Es gibt drei verschiedene Telezentrische Linsensysteme. Je nach gegebenem ÷ffnungsverh‰ltnis des
Fernrohrs kann entweder ein 2-faches, 3-faches oder ein 4-faches TZS in Kombination mit Abblen-
dung der Optik eingesetzt werden, um f/30 zu erhalten. Die Beobachtungsmˆglichkeiten und die Fle-
xibilit‰t eines Sonnenteleskops werden jedoch durch den abwechselnden Einsatz der TZS enorm er-
weitert.
Zum Beispiel empfiehlt es sich f¸r Detailbeobachtungen z.B. von Strukturen rund um Sonnenflecken
mit mˆglichst grofler ÷ffnung (= hohe Auflˆsung) zu arbeiten w‰hrend f¸r die Fotografie und Beobach-
tung von Protuberanzen, die durchaus Hˆhen von mehreren 100.000 km erreichen kˆnnen, ein gro-
fles Gesichtsfeld von Vorteil ist.
Das TZ-3 unterscheidet sich von beiden anderen TZ-Systemen dadurch, dass das Linsensystem f¸r
ein H-Etalon mit 46 mm Maximalgrˆfle ausgelegt wurde, um auch die groflen Research-Grade-Filter
von SolarSpectrum vollkommen auszuleuchten. Aus diesem Grund ist das Geh‰use auch beidseitig
mit 2" (50.8 mm) Gewinden ausgestattet, und es sind alle Adapter im Lieferumfang enthalten um das
TZ-3 beidseitig an 2" oder an T-2 (M42x0.75 mm) Gewinden anschlieflen zu kˆnnen. Alle Solar
Spectrum Filter werden ebenfalls beidseitig mit 2" und mit T-2 Gewinden ausgeliefert.
Strahlengang eines 6"/f6 Refraktors der mit einer 5-fach
Barlowlinse auf f/30 verl‰ngert wurde
Strahlengang eines 6"f/30 Refraktors. Diesen Zustand
stellt das Telezentrische System her!
Telezentrische Systeme TZ-2, TZ-3 und TZ-4
Baader Telezentrische Linsensysteme (TZS) f¸r die
Sonnenbeobachtung mit schmalbandigen H- Filtern
Zur erfolgreichen Sonnenbeobachtung mit schmalbandigen Linienfiltern (Halbwertbreiten unter 1
Angstrˆm) der Marken "Solar Spectrum" und "Day Star" ist ein Teleskop mit einem ÷ffnungsverh‰ltnis
von mindestens f/30 die Voraussetzung. Dieses ÷ffnungsverh‰ltnis l‰sst sich entweder durch Abblen-
den der Objektivˆffnung ñoder vorzugsweise durch Brennweitenverl‰ngerung mit einem "Telezentri-
schen System" (TZS) ñerzielen. Telezentrische Systeme sind nicht mit Barlowlinsen gleichzu-
setzen (siehe Grafiken)! Nur mit einem TZS entsteht ein paralleles Strahlenb¸ndel, nur damit ist eine
gleichm‰flige Darstellung der chromosph‰rischen Strukturen ¸ber das gesamte Bildfeld des Tele-
skops gew‰hrleistet.
Generell sind nur Refraktoren und katadioptrische Teleskopsysteme mit Hauptspiegelfokussierung
(z.B. Schmidt-Cassegrain Teleskope) zur H-alpha Sonnenbeobachtung geeignet, bei den meisten an-
deren Teleskopsystemen (Newton) steht bauartbedingt der erforderliche Fokussierweg zum Anschluss
des Zubehˆrs zur H- Beobachtung nicht zur Verf¸gung.
Einsatz der Telezentrischen Linsensysteme
Es gibt drei verschiedene Telezentrische Linsensysteme. Je nach gegebenem ÷ffnungsverh‰ltnis des
Fernrohrs kann entweder ein 2-faches, 3-faches oder ein 4-faches TZS in Kombination mit Abblen-
dung der Optik eingesetzt werden, um f/30 zu erhalten. Die Beobachtungsmˆglichkeiten und die Fle-
xibilit‰t eines Sonnenteleskops werden jedoch durch den abwechselnden Einsatz der TZS enorm er-
weitert.
Zum Beispiel empfiehlt es sich f¸r Detailbeobachtungen z.B. von Strukturen rund um Sonnenflecken
mit mˆglichst grofler ÷ffnung (= hohe Auflˆsung) zu arbeiten w‰hrend f¸r die Fotografie und Beobach-
tung von Protuberanzen, die durchaus Hˆhen von mehreren 100.000 km erreichen kˆnnen, ein gro-
fles Gesichtsfeld von Vorteil ist.
Das TZ-3 unterscheidet sich von beiden anderen TZ-Systemen dadurch, dass das Linsensystem f¸r
ein H-Etalon mit 46 mm Maximalgrˆfle ausgelegt wurde, um auch die groflen Research-Grade-Filter
von SolarSpectrum vollkommen auszuleuchten. Aus diesem Grund ist das Geh‰use auch beidseitig
mit 2" (50.8 mm) Gewinden ausgestattet, und es sind alle Adapter im Lieferumfang enthalten um das
TZ-3 beidseitig an 2" oder an T-2 (M42x0.75 mm) Gewinden anschlieflen zu kˆnnen. Alle Solar
Spectrum Filter werden ebenfalls beidseitig mit 2" und mit T-2 Gewinden ausgeliefert.
Strahlengang eines 6"/f6 Refraktors der mit einer 5-fach
Barlowlinse auf f/30 verl‰ngert wurde
Strahlengang eines 6"f/30 Refraktors. Diesen Zustand
stellt das Telezentrische System her!
Telezentrische Systeme TZ-2, TZ-3 und TZ-4
Light beam of a 6"lens telescope, which was
extended to f/30 with a barlow lens
Light beam of a 6"lens telescope, which was
extended to f/30 with a telecentric system

10 Manual: SunDancer II
temperature of the lter 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 lter with articially 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 bafe 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 magnications 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 lter. It shimmers golden
when you look into the SunDancer from the telescope side. This block lter is absolu-
tely necessary to protect the actual H-alpha lter 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 lter!).
Attention: Using it with a telecentric without
this additional block lter would destroy the
etalon just as much as using it without D-ERF
on larger telescopes than 80 mm.
The 3x telecentric (#4696070) is also
available without blocking lter, e.g. for use on
other H-alpha lters. The blocking lter is not
available separately.
A 4x telecentric with integrated blocking
lter is planned in the long term, the existing
blocking lter 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.
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.