Baader SunDancer II Telecentric System TZ-4S

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Baader SunDancer II Telecentric System TZ-4S

# 1363080

€ 385.00 Price excl. German VAT tax (19%): € 323.53

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  • Delivers a plane-parallel, achromatic beam of light with 36 mm diameter
  • Designed especially for H-alpha and CaK subangstroem etalon filters
  • Includes a ½" filter cell for the 2 nm block filter of the Baader SunDancer II H-alpha filter
  • Can also be used in place of a Barlow lens, expands the telescope focal length by 4x
  • BBAR (Broad-Band Anti-Reflection) coating
  • Anti-reflective thread and blackened lens edges against reflections and for maximum contrast
  • Image circle 36 mm, in a nominal in 97 mm from base of the T-2 thread
  • 1¼" and 2" nosepiece with 1¼" filter thread, T-2 thread on camera side
  • 12.5 mm (1/2") filter exchange tool included
  • 5-year warranty if handled properly
Important note: We deliver the SunDancer II H-alpha only with TZ-3S. An alternative cover with TZ-4S is unfortunately not possible.

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Baader SunDancer IIBaader SunDancer II 4x Telecentric System TZ-4S

Telecentric systems are mainly used in H-alpha filters for solar observation, where the 1/100 lambda plane-parallel etalon in the H-alpha filter requires a perfectly parallel beam of light over the entire image. These telecentric systems deliver very sharp images, but are usually only optimised for the H-alpha wavelength.

This achromatic SunDancer 4x telecentric is designed for the entire visible spectrum and can therefore not only be used on H-alpha systems, but the TZ-4S, as well as the Baader SunDancer II Telecentric System TZ-3S (#1363070 , € 365,-) can also be used instead of a Barlow lens. Due to the parallel beam of light, it is very good-natured with regard to the working distance: While the magnification factor of a Barlow lens changes with the distance to eyepiece or camera (zoom eyepieces are also based on this principle), the magnification factor and image quality of the TZ-4 do not change, even if the camera or eyepiece is mounted well behind the nominal working distance (97 mm from the base  of the T-2-thread).

The achromatic SunDancer II TZ-4S illuminates an image circle of 36 mm at a distance of 97 mm from the base of ther T-2-thread. The contrast is better than with the common methods used for higher magnifications: simple barlow lenses or eyepiece projection. With the 4x telecentric system, high magnifications for observing the solar system can be achieved even with long focal length orthoscopic eyepieces. The eye relief of the eyepieces used does not change, too! The focus position changes only 3 mm outward when using the 2" nosepiece of the telecentric, compared to a 2" eyepiece.

The connection on the telescope side is made via a dual 1.25"/2" nosepiece with safety kerfs (these prevent tilting due to an incorrectly positioned safety groove and at the same time provide a secure hold). On the camera side, the T-2 thread provides a tilt-proof, fixed connection even to heavy cameras or to T-2 eyepiece clamps. For the T-2 thread, adapter rings are available for almost all common connection systems (e.g. M48 / 2"/ M68).

Zum Gebrauch der TZ-4S mit dem SunDancer II H-alpha-Filter (links) muss der glänzende Blockfilter aus der TZ-3S mit roter Banderole entnommen und in die TZ-4S eingesetzt werden.
To use the TZ-4S with the SunDancer II H-alpha filter (left), the shiny block filter must be removed from the TZ-3S (with red label) and inserted into the TZ-4S.

The TZ-4S in use with H-alpha-Filters

The TZ-4S was specially designed for the  Baader SunDancer II H-alpha Filter (#1363056 , € 3545,-) and replaces the original 3x telecentric. This allows to use the SunDancer II H-alpha filter also on telescopes with f/7-f/8 with the optimal focal ratio of about f/30. Please note: For this, the 12 mm 2 nm H-alpha blocking filter, which is pre-installed in the front of the TZ-3S, must be installed in the TZ-4S. This blocking filter is not available separately. The ideal working distance when using the SunDancer II is then 70 mm from the base of the T-2 thread of the SunDancer II H-alpha filter (instead of 65 mm with the original TZ-3S).

For H-alpha filters with up to 36 mm diameter with their own block and energy protection filter (e.g. SolarSpectrum filter), the TZ-4S can be used instead of the long-building Telecentric System TZ-4 (4x focal length) (#2459256 , € 387,-) .

The SunDancer II Telecentrics

  • Baader SunDancer II Telecentric System TZ-3S (#1363070 , € 365,-) with gold anodized label: Achromatic 3x telecentric with 95 mm working distance from the base of the T-2 thread and 27.5mm clear aperture. Provides the desired focal ratio of f/30 on telescopes with f/10. This telecentric is also available without the SunDancer II H-alpha filter, but then only without the 2 nm block filter of the H-alpha filter. For clear identification, this telecentric has a gold-colored anodized banderole.
  • TZ-3S with 2nm block filter and red anodized label: Achromatic 3x telecentric of the Baader SunDancer II H-alpha Filter (#1363056 , € 3545,-) is equivalent to the Baader SunDancer II 3x Telecentric TZ-3S, but additionally contains a 2nm (FWHM) block filter. It shimmers golden when you look into the SunDancer from the telescope side. This block filter is mandatory to protect the actual H-alpha filter from solar radiation. For clear identification, this telecentric has a red anodized band, otherwise identical to the Baader SunDancer II Telecentric System TZ-3S (#1363070 , € 365,-) . Please note: We deliver the SunDancer II only with TZ-3S. An alternative cover with TZ-4S is unfortunately not possible.
  • Baader SunDancer II Telecentric System TZ-4S (#1363080 , € 385,-) with violet anodized label: Achromatic 4x telecentric with 97 mm working distance from the base of the T-2 thread and 36mm clear aperture. Provides the desired focal ratio of f/30 on telescopes with f/7.5. For clear identification, this telecentric has a violet anodized label. This telecentric does not include the 2 nm blocking filter of the H-alpha filter; for use with the SunDancer II, the 2 nm block filter must be converted from the TZ-3S of the SunDancer II filter to the TZ-4S. The use with large SolarSpectrum H-alpha filters with already integrated block filter and additional energy protection filter is possible without this additional 2 nm block filter.

The blocking filter reflects the sunlight just before the etalon and the telecentric system. This protects the etalon from excessive heat. In addition, an etalon also transmits wavelengths that are a multiple of the desired transmission line; these are also stopped by the blocking filter, too. The blocking filter or the TZ-3S with pre-installed blocking filter are not available separately.

Baader SunDancer TZ-3S
The 3x-Telecentric TZ-3S without block filter, recognizable by the gold-colored ring
Baader SunDancer II H-alpha Filter
The 3x-Telecentric with integrated block filter is only available together with the SunDancer II H-alpha filter. Here the block filter of the SunDancer II is pre-installed, the version is recognizable by the red ring.
Baader SunDancer II Telezentrisches System TZ-4S
The 4x-Telecentric TZ-4S
without block filter, recognizable by the
violet ring


TZ-optical systems are essential for undeteriorated performance of heated SolarSpectrum filters:

Please note that for H-alpha observations below 1 Ang halfbandwidth (FWHM) a telecentric lens system is absolutely mandatory, in order to achieve the recommended focal ratio of f/30 to (preferably) f/40! Because only with a telecentric approach you can create a perfectly parallel optical path which is essential for the unrestricted function of such a complicated etalon.

A TZ-lens-system is an ESSENTIAL prerequisite. One could also bring a telescope to a focal ratio of f/30, but this does not mean at all that a parallel optical path is created. And mind you, a still slightly conical optical path with f/30 sent into an etalon with 0.5 Ang FWHM would only provide the contrast as if the filter had a FWHM of 0.7 Ang or much worse.

The main difference between TZ-4S and the older TZ-4 are adaptation to the telescope ( the TZ-4 uses T-2-threads for a stable connection – perfect for the long SolarSpectrum filters) and their working distance. The free apertureof the TZ-4S is comparable with about 35 mm and does not fully illuminate the largest SolarSpectrum filters with 46 mm filter diameter. But it doesn't always have to be a TZ-4. The 2" Research Grade TZ-3 Telecentric System (3x focal length) (#2459257 , € 445,-) with 46mm clear aperture is much better in terms of optical calculation than the 20 year older TZ-4.  So it makes sense for the user to start with a TZ-3 RG and rather stop down the telescope aperture to get to f/30. This will bring out the real contrast of the chosen SolarSpectrum-filter much better than with a poorly matched system where, for example, the older TZ-4 has a smaller clear aperture than the Solar Spectrum-Etalon would require. In the long run, a recalculated, large RG TZ-4 is in preparation - it is worth to wait for it and to get familiar with H-alpha observation with the TZ-3 first. Later, one will surely need both systems (RG-TZ-3 and RG-TZ-4) and will have to stop down the telescope aperture as needed.

Only AFTER the H-alpha etalon you can extend the field size by reducing the f-ratio with adding the new ResearchGrade telecompressor 0.4 into the optical train.

Basically - a Barlow lens has no place in an H-alpha system!

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Additional Information

EAN Code 4047825052124
Manufacturer Baader Planetarium
SKU (#) 1363080
Outer Connection (lens sided) ø 1¼" (31.75 mm), ø 2" (50.8mm)
Outer Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2)
Image Field 36 mm
Focal length extension 4x
Inner Diameter / Clear Aperture (mm) 36 mm
Usage for H-alpha observation with SolarSpectrum filters
Backfocus 97 mm ab dem Gewindeboden des T-2-Gewindes (Bei Verwendung mit Baader SunDancer II H-alpha-Filter: 70 mm ab dem T-2-Gewindeboden des H-alpha-Filters)

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4 Item(s)

Chris 130/05/2023 11/05/202314:50
  • Rating:
Endlich volle Öffnung mit optimalem Kontrast bei Sonne-H@ möglich
Ich habe seit Ende Dezember 2021 den Sundancer II mit großem Erfolg und Freude im Einsatz.
Zu dem Zeitpunkt musste ich meinen optisch hervorragenden Takahashi FS-128 5"-Fluoritrefraktor mit einer Irisblende auf Anfangs 80mm, später durch den D-ERF auf 100mm abblenden, was auch schon eindrucksvolle H@-Beobachtungen und Aufnahmen ermöglichte.

Die damalige Entscheidung etwas mehr für das Zubehör für mehr Öffnung zu investieren (größerer D-ERF) hat sich nun voll ausbezahlt. Die lang ersehnte Telezentrik 4x habe ich mir Ende Juli hier bei Baader erworben.Mit der 4x Telezentrik kann ich nun die volle freie Öffnung von 128mm statt 100mm anwenden und bekomme sogar ein Öffnungsverhältnis von F=32 hin.
Durch die daraus resultierende Brennweite von 3.1 Meter auf 4.15 Meter ermöglich jetzt noch eine deutlich feiner Detailerfassung.

Wie einige Kunden zuvor schon beschrieben haben bekommt man mit der neuen 4x Telezentrik einen deutlich besseren Kontrast und durch den Öffnungsgewinn auch mehr Helligkeit.

Insbesondere erkennt man auf der Chromosphäre noch mehr Einzelheiten und hat ein "kräftigeren" Punch im Bild.
Protuberanzen, und gerade eben auch sehr kleine Protuberanzen, sind so fein dargestellt, daß man quasi im Minutentakt Veränderungen verfolgen kann.
Ich habe Dazu einige Aufnahmen mit in der Bewertung hinzugefügt (unter anderem eine 2-Minuten gif-Animation sowie 60x-Zeitraffer Videos.)

Auf den Bildern sieht man den Größenvergleich zwischen 3x und 4x Telezentrik. Klasse finde ich die jetzt auch größeren Linsenelemente.

Als Anregung hätte ich den Vorschlag den kleinen Frontfilter vom Sundancer II gleich eingebaut mitzuliefern oder als Einzelteil (natürlich gegen Aufpreis) mitzuliefern oder erwerben.
Man wäre dann flexibler im Einsatz und braucht nur die Telezentrik durch Umschrauben des Sundancer II-Filterkopfes austauschen.

Was aber auch praktisch ist, daß man die Telezentrik ohne Filter wie eine sehr hochwertige Barlow (3x oder 4x) für z.B. Planetenaufnahmen verwenden kann.Hab ich bei mir zur Zeit so mit der 3x Telezentrik am Handhaben.Sonst bleibt natürlich der FFC Hierfür das Maß aller Dinge, aber wenn man schon die Telezentrik hat, ist das eine sehr praktische Sache.
Sozusagen eine sehr nützliche "Zweckentfremdung".

Der große Vorteil an der 4x Telezentrik ist vor Allem daß jetzt Besitzer von Großen Refraktoren 5,6,7 oder gar 8" das Potential von Optik und Sundancer II voll ausschöpfen können.

Ich kann nur jedem Besitzer vom Sundancer II (und sogar andere H@-Filter sollen funktionieren) raten die Derzeit 385.- für die 4x Telezentrik zu investieren - es lohnt sich echt.

Die Entwicklungszeit wo das Baader Team für die 4x-Telezentrik aufgebracht hat haben sich voll gelohnt, ist ein Klasse Produkt geworden.
  • Volle Öffnung jetzt anwendbar /Kontrast und Helligkeit /Sehr gute Optische Qualität /Als Premium Barlow anwendbar
  • Sundancer II Frontfilter muss beim Wechseln umgeschraubt werden - Toll wäre eine Einzelerwerbbarkeit des kleinen Schutzfilters zum Vorbereiten von beiden Telezentriken
Über dieses Urteil freuen wir uns besonders – die Bilder zeigen was ohne große Nachbearbeitung möglich ist. Wir werden uns die Kritikpunkte zu Herzen nehmen und planen den 12.5 mm großen, hartvergüteten H-alpha-Vorfilter auch als Einzelprodukt verfügbar zu machen. Dieses hochkomplexe Vorfilter stellt einen bedeutenden Kostenfaktor dar – was einer der Gründe ist weshalb der SunDancer II deutlich teurer ist als scheinbar ähnliche Produkte.
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Petrus Kurppa 230/08/2023 19/08/202309:37
  • more than 3 month(s)
  • Rating:
I was happy to receive my TZ-4S telecentric system with a fast delivery time new product from Baader Planetarium. Later I will get Sundancer II and use this telecentric system for it so it will be easier to get a proper f/10 ratio with my different telescopes. TZ-4S comes with a tool to swap the necessary blocking filters from TZ-3S to TZ-4S.

It is possible to use TZ-4S in a similar way as the Barlow lens too. I decided to try it with my Lunt80THa solar telescope. I attached the camera body directly to the TZ-4S T2 tread and other side to the solar telescope's blocking filter. No problems and no odd reflections, which I have noticed sometimes with other brands' products for solar imaging. Overall I am very satisfied with the design and quality of this product.
  • Design and high quality
  • Nothing found out yet
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Astro Tafelberg 203/07/2023 23/07/202317:04
  • Rating:
TZ-4s am SunDancer II
Kürzlich wurde ein Review vom Einsatz des neuen TZ-4s in Kombination mit dem Solar Spectrum Filter präsentiert - hier nun ein Erfahrungsbericht für den eigentlich gedachten Einsatz mit dem SunDancer II:

Bis dato habe ich den SunDancer II an meinem 150mm ED APO TRIPLETT mit dem im Lieferumfang befindlichen TZ-3s verwendet. Dies ergab mit dem f7 Refraktor also "nur" f21, also weit von den empfohlenen f30 entfernt, aber die Ergebnisse waren auch damit recht gut.
Mit dem TZ-4s erreiche ich nun f28 und konnte das heute am 23. Juli 2023 erstmals an der Sonne testen. Das Seeing war leider nur durchschnittlich, dennoch konnten folgende Schlussfolgerungen getätigt werden:
1) Das ganze System wird gutmütiger, sprich kein Problem mit Newtonringen, wie sie noch leicht bei Verwendung mit dem TZ-3s (trotz Tiltung der Kamera) sichtbar gewesen sind.
2) In Kombination mit dem TZ-4s erhöht sich, erwartungsgemäß, auch der Kontrast - nicht dramatisch, aber bereits im Live-Bild auf dem Laptop erkennbar.
  • Verarbeitung, Qualität
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P. Proske 187/07/2023 07/07/202307:55
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Field report: „Baader SunDancer II Telecentric System TZ-4S“
In June 2023 I was offered the opportunity to test the new "Baader SunDancer II Telecentric System TZ-4S" (short TZ-4S).

Since I had already been working with the classic, long telecentric systems TZ-4 and TZ-3 for 2 years, my interest and curiosity for this TZ-4Short were immediately aroused. I wanted to know how the new system had developed and how it compared to the older TZ-4.

My Conclusion: The new "Baader SunDancer II Telecentric System TZ-4S" is a wonderfully compact and high-quality telecentric system that feels at home on both small and large telescopes. Its connection options allow for versatile use. And when stowed away, the system takes up no more space than an eyepiece.

To me, the new TZ-4S represents a consistent and logical evolution of its several-year-old predecessor.
  • Compact, relatively light, robust, Standard connections, very short working distance for TZ systems
We provided our customer Mr. Rüdiger Proske with the new Baader SunDancer II Telecentric System TZ-4S for a comparison test with the longer TZ-4. Most interesting was the question how the TZ-4S, which was primarily designed for the SunDancer II H-alpha filter, harmonizes with his large SolarSpectrum H-alpha filter.

We are very happy about his very positive conclusion and his field report.

Please read the detailed report of Mr. Rüdiger Proske here:
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