2" Research Grade TZ-3 Telecentric System (3x focal length)

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2" Research Grade TZ-3 Telecentric System (3x focal length)

# 2459257

€ 445.00 Price excl. German VAT tax (19%): € 373.95

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  • Research Grade Telecentric Unit, featuring an oversized pick up expanding lens set and 2" (50.8mm) threads on both sides – T-2 Adapter and 2" m/f inverter ring are both included as standard accessories
  • 46mm clear aperture at the H-alpha-filter entrance side - suitable for research grade SolarSpectrum H-alpha filters
  • Large working distance of 250mm for optimized focal length reduction with a telecompressor and suitable room for adapting a binocular viewer
  • Aplanatic, with 3x focal length extension to achieve a parallel f/30 beam in conjunction with ~f/10 optics systems – free of field curvtare
  • Primarily calculated and produced for H-alpha at 656,3 nm, delivering 99% Strehl (definition brightness) depending on the used telescope system
  • Diffraction limited design with about 80% Strehl also at 396 nm (CaK)

Please note: when using as a telecentric for H-alpha or CaK solar observation, it is mandatory to include a suitable enegy protection filter in front of the telescope aperture to prevent damage to the lens groups in the telecentric due to overheating. Heat/melting damage is not a warranty case, but only occurs due to improper operation.

For H-alpha, please use a

The Triband ERF coating of a Triband-SCT - Schmidt-Cassegrain-based Multi-Purpose-Telescope, for Sun and Deep Sky is suitable for both H-alpha and CaK.

Product Questions and Answers

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A couple of followup questions. 1) I noticed the TZ-3 tube has 3 'sections' longest being in front, shortest at rear holding 'collimation'/'pickup' lens and a middle section that appears to be just a spacer. Can the middle section be removed (omitted) such that rear lens becomes closer to front 'input' lens.
2) Is the middle section intend for removal to provide for an alternate closer location of pickup lens or is this just a manufacturing convenience to be a separate part (reuse of existing parts?)?
3) What would be the characteristics of the resulting output beam? Diameter, F#, impact on position of TZ relative to main objective (assume that would not change), impact on distance from TZ to final focal plane which was originally 250mm?
Question by: Anthony Sarra on Mar 12, 2017 8:05:00 PM | 1 Answer(s)

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Can the Baader Telecentric lenses be used like ordinary Barlows, e.g. for visual observation or imaging (from UV to IR) of the planets?
Question by: Jack on Feb 10, 2017 7:21:00 AM | 1 Answer(s)

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Other than the obvious differences in magnification and position of the focal spots, is the TZ3 significantly different from the TZ2 ? I currently have a TZ2 on a home-built Halpha system and it is giving great results but I'd like a little more magnification. The TZ3 seems to have a different appearance than the TZ2 and TZ4 and is marketed toward SolarSpectrum etalons. Is there anything special about the TZ3 that makes it significantly different from the TZ2 and TZ4 ?
Question by: Bob on Aug 24, 2021 2:33:00 AM | 1 Answer(s)

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Which side goes into the telescope and which goes into the solar filter? I assume the side with the small lens needs to face the telescope, and the side with the large lens should face the H-alpha filter / camera. Is that right? I find that counter-intuitive, because the cone of light should be wider on the telescope side, is that not so?
Question by: Florin Andrei on Dec 1, 2020 3:52:00 AM | 1 Answer(s)

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1. What is the main difference between "Research" TZ-3 and regular TZ-4 other than magnification ratio?

2. Second difference I can spot - I see that TZ3 is optimized for 2 lines, while TZ4 is only for 1 line. Is it difference only on coatings or optical design too?

3. Should I expect same high quality when using TZ4 at Ha as on TZ3 at Ha?

4. I can also see that case is different. Is there any reasoning/causes for that? I see that TZ3 fits in 2" focuser, while TZ4 has weird shape and can only be mounted by the thread, or I am missing something.

Best regards,
Question by: Mikhail on Nov 27, 2018 6:38:00 PM | 1 Answer(s)

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1) From an optical standpoint, what happens if the backfocus distance on the telescope is too short and the focal point lies in front of the marking on the TZ-3?
2) In that case, what amount of deviation from the specified 86mm distance would you consider acceptable when working with a 700mm F8 reflector and a 0.7Å+-0.05 etalon?
Question by: Robert on Apr 22, 2022 1:28:00 PM | 1 Answer(s)

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If using the TZ-3 with a 32mm CA SolarSpectrum ASO model is some light lost since the TZ-3 is designed to produce a 46mm output beam? If 'yes', light is lost, when used with a 32mm etalon can the rear lens of TZ-3 be moved closer to the front / input lens to produce an exit beam more closely matched to the 32mm CA of the ASO model Ha filter and thus produce a brighter image in an eyepiece?
Question by: Anthony Sarra on Mar 12, 2017 7:25:00 AM | 1 Answer(s)

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Baader Telecentric Systems for focal length extension

for supplying a parallel optical beam and for providing sufficient backfocus, in conjunction with any SolarSpectrum H-alpha filter

Telecentric optics sets are often confused with a barlow lens. Both can be used to increase the focal length. Telecentric assys are designed so that the exit pupil seemingly is positioned at infinity, which means that the center ray from any point in the field appears to come from infinity and is therefore perpendicular to the image plane and parallel to the optic axis. This means that the off axis beam does arrive at the image plane with the same angular geometry as the axial rays. All field elements look as if they where on axis, across the image plane and - unlike to a barlow lens - the edge field rays are not tipped bundles.

Because all the principal rays across the image plane are perpendicular to the image plane, the rays at the edge of the field will pass through an etalon just in front of the focal plane with exactly the same geometry as the rays on axis. So in an f/30 telecentric optical arrangement, the etalon sees the exact same geometry clear across the field, and the spectral bandpass does not shift in wavelength across the entire field of view.

Starting from an aperture ratio of ~f/15 (+2x Telecentric), ~f/10 (+3x Telecentric) or ~f/7.5 (+4x Telecentric), the Baader TZ-systems will create a parallel beam with ~f/30 aperture ratio. In the case of largely deviating telescope focal lengths, the clear objective aperture of the telescope should be reduced in diameter to the point that the final resulting f/ratio is close to f/30 again (we do offer a suitable iris-diaphragm for this purpose).

TZ-system working distances – when measured from their rear lens – range from 200mm for the TZ-2 to 230 mm for the TZ-4 - to 250 mm for the TZ-3. This provides enough room for the H-alpha filter housing and most any accessories, e.g. a Baader 2" mirror diagonal or any conceivable camera device. The generous room of the TZ-3 will also accommodate a binocular viewer when it is mounted onto the SolarSpectrum body by means of a Baader BBHS T-2 star diagonal. All TZ-coatings are matched to the different lens glass-substrates and optimized for maximum throughput at 656 nm. Still the TZ-3 especially also works for CaK at 396 nm. The TZ-3 Strehl-ratio is well above 80% at 396 nm

Please also note the detailed PDFs under the Tab "Downloads" for further information


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 optically - or by means of a Barlow lens - 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.

It doesn't have to be a TZ-4. The new 2" Research Grade TZ-3 Telecentric System (3x focal length) (#2459257 , € 445,-) 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 newly calculated, 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. In the end one will certainly need both systems (RG-TZ-3 and RG-TZ-4) and adjust the telescope aperture  individually - as the system would require to enable an f/ratio of f/30 at minimum or f/40 as optimum. 

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 4047825008695
Manufacturer Baader Planetarium
SKU (#) 2459257
Net weight (kg) 0.21
Inner Connection (lens sided) M42 x 0.75 (T-2)
Outer Connection (lens sided) 2"/SCT Thread (50.8mm)
Outer Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2), 2"/SCT Thread (50.8mm)
Focal length extension 3x
Usage for H-alpha observation with SolarSpectrum filters

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Apollo 109/04/2023 20/04/202301:04
  • Rating:
TZ3 is essential for maximum aperture possible in an amateur hydrogen alpha etalon system.
The Tz3 is literally the only opportunity to exploit large etalon's for rear mounted telescope operation.
I use mine with a completely modified 50mm etalon. I modified my Baader planetarium diamond steel track focuser to incorporate a Baader Planetarium 75m D-erf and the TZ3. I even integrated the Baader planetarium 3.5nm enforced h-alpha filter into the bds prior to the tz3. This is nirvana!
  • Largest aperture available to amateurs with SCT threads.
  • There is nothing better :)
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Alan Jadanić 37/02/2021 07/02/202107:09
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Solar imaging with the TEC 140 f/4 Fluorite Apochromat and TZ-3
On 2 June 2021, our customer Alan Jadanić sent us these amazing solar images taken with the TEC APO 140 f/7 Fluorite Apochromat. He used our kam unser D-ERF Energy rejection filter 75mm, a Solar Spectrum H-alpha Filter and the Research Grade TZ-3 Telecentric System (3x focal length). Thank you!

We would like to empahasise the multifunctional usability of the TEC APO 140 FL for DeepSky, visual observations and H-alpha. This optic can really be used day and night and is therefore a real all-rounder.

An excerpt from the experience report by Alan Jadanić

"Dear Mr. Baader,

... TZ3 works just fine and even at f/26 (I have variable diaphragm on) you can clearly see all the details. Closing down the aperture improves the contrast, but you loose some of the light entering your system. So if it is not necessary you don't have to be around f/30 or more. If you want the full solar disc you can use just a telescope with D-ERF and RG 38 but without TZ3. However, then you have to close down the diaphragm a lot if you want to get similar contrast. In that case you loose some of the details due to very small aperture. But it is a trade off for getting the whole solar disc..."

Find more in our blog aboute "Solar imaging with the TEC 140 f/4 Fluorite Apochromat and TZ-3":

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Enrico 276/10/2020 03/10/202015:07
  • Rating:
Sunshine TZ-3
Habe mir die Baader TZ-3 zugelegt, um das Sunshine 70/700 F10 auf F30 zu erweitern. Mir war es wichtig das Etalon besser auszuleuchten. Das funktioniert mit der TZ-3 ordentlich. Trotz Schleierwolken sind ganz gute Bilder entstanden.

Jetzt besteht das System aus einem 75mm Baader D-ERF, 4cm gekürzter 70/700 Refraktor mit Velourfolie, gedrehte Aufnahme, zum Fokussierter von TS, Baader TZ-3, gedrehte Hülse 75mm mit Velourfolie, 20mm PST Etalon ohne Kolimatonslinsen mit Adapter auf 1.25" Aufnahme ca 6cm, Spiegel mit ITF Filter und 15mm Blockfilter, Kameras ZWO ASI 1600 und 290

Um in den Fokus nach der TZ-3 zu kommen, habe ich alles bis zum Kamerachip mit dem Messschieber ausgemessen. 240-260mm

Das Bild ist schärfer und die Granulation kommt auch besser rüber! Keine Reflexe oder Geisterbilder. Saubere Arbeit.
Ist sein Geld wert!
  • Verarbeitung, F30 am Etalon
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JR Roudier 146/05/2018 27/05/201808:28
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Très utile
J'avais déjà le TZ2 et le TZ4, mais pour utiliser ma caméra Basler 1920/155 au mieux il me fallait un 3x. C'est donc le TZ3 qui m'est très utile.
Je l'utilise en observation visuelle et donc en imagerie.
  • Très bonne finition, filetages M48, ce qui donne une bonne ouverture.
  • Les capuchons avant et arrière ne tiennent pas très bien. Il faudrait des capuchons vissant comme sur les autres TZ.
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Michel M. 28/01/2018 29/01/201807:41
  • Rating:
Test of TZ-3 telecentric system
My solar instrument consists of the following parts: first a full aperture Baader ERF filter, next a refractor Orion 100/1000, next a blocking filter, next the TZ3 telecentric system, next the central part of Daystar Quark filter (in fact the Ha interferentiel filter), next a diagonal mirror, next a tilter to avoid fringes in the image and to finish ZWO cmos camera. So the total focal is 3000mm, giving a solar image size of about 27mm. The refractor is in parallel with my 300mm Meade SCT on an homemade azimuthal mount.

The system can be used in visual too, by removing the camera and place an eyepiece.
The first notable thing in visual observation is the contrast of images: it's a lot better than with the previous telecentric barlow included in the Quark. The image is sharp in all the field of view. The Fabry Perrot filter seems to work fine with the quasi-parallel rays comming from the TZ3.
With the camera, it’s mandatory to have a tilter, otherwise you have fringes due to interferences. And again the images after processing are very good. It is the first time I am able to get images with such details.

To conclude, my TZ-3 telecentric has really improved my sight of the sun, and now if I want to go farther I should buy a very expensive narrow Ha filter, perhaps later.
In the next month, I will try the TZ3 on planetary images with my 300mm Meade SCT.

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Randy 344/12/2017 11/12/201702:29
  • Rating:
Baader TZ3
I had been imaging the sun for a long time now but nobody made a telecentric 3x until now. My telescope is a F8 refractor and a 2x would only give me a F16 system while the available 4x would give me a F32 all but useless on most days where the seeing conditions are not perfect. Glad to see that Baader has answered the calls for a good telecentric lens of 3x.
  • I like the large aperture of the lens, the well made optics, and the fine machining of the lens system.
  • This is a bit picky but it could have better lens covers that fit a bit tighter.
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W. Paech 291/10/2017 19/10/201711:40
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Erfahrungsbericht zu TZ-3 und RG-4 für die Sonnenbeobachtung
Wie schon das Baader TZ-2 - eingesetzt zusammen mit dem TC 0.7fach – ist das neue TZ-3 zusammen mit dem RG TZ 0.4fach ein ausgesprochen variables System für die Sonnenbeobachtung im H-alpha Licht.

Es ist über die flexible Brennweitenreduzierung beliebig an Seeinbedingungen anpassbar. Bilder, aufgenommen mit dem TZ-3 zeigen eine enorme Detailfülle, die Bildauflösung liegt bei 110mm Öffnung unter 1 Bogensekunde und die Bilder sind über das komplette Gesichtsfeld „knackscharf“ bis zum Bildfeldrand.

Durch die variable Brennweitenreduzierung mit dem RG TC 0.4fach und gegebenenfalls einer zusätzlichen T2 Verlängerung habe ich aktuelle Seeingbedingungen und geforderte Gesichtsfeldgrößen optimal unter Kontrolle. Ein weiterer Vorteil des RG TC 0.4: die Belichtungszeiten der Einzelbilder bei der Aufnahme eines avifiles reduzieren sich dramatisch und auch bei Mosaiken gibt es Zeitersparnissen, allein durch den Umstand, dass weniger Bildsegmente erforderlich sind.

Alles in allem für mich eine optimale Lösung, um mein Sonnenteleskop mit einer Öffnung von 110mm betreiben zu können, von daher

5 Sterne für Mechanik und optische Performance des TZ-3/RG TC 0.4fach und noch einmal
5 Sterne für die Firma Baader Planetarium, die immer wieder durch eigene Entwicklungen die Beobachtungsmöglichkeiten der Amateursonnenbeobachtung erweitert und damit bereichert .
Hier zu lesen ist nur das Fazit des Testberichts. Den ausführlichen Bericht mit vielen weiteren Bildern finden Sie als PDF unter dem Tab "Downloads"
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