About this product
Model: baader_1363080
Part Number: 1363080
Baader Sundancer II 4x Telecentric System TZ-4S
To use this TZ-4S, you need the 12 mm 2 nm H-alpha blocking filter, which is pre-installed in the front of the TZ-3S. This blocking filter is not available separately.
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 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), can also be used instead of a Barlow lens. Due to the parallel beam of light, it is very forgiving about the working distance.
While the magnification factor of a Barlow lens changes with the distance to the eyepiece or camera (zoom eyepieces are also based on this principle), the magnification factor and image quality of the TZ-4 does 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 the T-2 thread.
The contrast is better than with the standard methods used for higher magnifications: IE, 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 either! 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 T-2 eyepiece clamps. For the T-2 thread, adapter rings are available for almost all standard connection systems (e.g. M48 / 2"/ M68).
The TZ-4S in use with H-alpha Filters
The TZ-4S was specially designed for the Baader SunDancer II H-alpha Filter (#1363056 ) and replaces the original 3x telecentric. This also permits using the SunDancer II H-alpha filter on telescopes with focal ratios of f/7-f/8 with the optimal focal ratio of about f/30.
Please note: The 12 mm 2 nm H-alpha blocking filter, which is pre-installed in the front of the TZ-3S, must be installed in this TZ-4S. This blocking filter is not available separately.
The ideal working distance when using the SunDancer II is 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 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 )
Clear Aperture Comparison
The SunDancer II Telecentric Features
- Baader SunDancer II Telecentric System TZ-3S (#1363070 ) with gold anodised 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-coloured anodised banderole.
- TZ-3S with 2nm block filter and red anodised label: Achromatic 3x telecentric of the Baader SunDancer II H-alpha Filter (#1363056 ) 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 anodised band, otherwise identical to the Baader SunDancer II Telecentric System TZ-3S (#1363070 ). Please note: Baader 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 ) with violet anodised 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 an f/7.5 focal ratio. For clear identification, this telecentric has a violet anodised 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. 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; the blocking filter also stops these. The blocking filter or the TZ-3S with pre-installed blocking filter are not available separately.
Important Note
TZ-optical systems are essential for the undeteriorated performance of heated SolarSpectrum filters:
Please note a telecentric lens system is mandatory for H-alpha observations below 1 Ang half bandwidth (FWHM) to achieve the recommended focal ratio of f/30 (preferably) f/40! Because only with a telecentric approach can you 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 a parallel optical path is created. Please note 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 is 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 aperture of the TZ-4S is comparable to approx 35 mm and does not fully illuminate the largest SolarSpectrum filters with a 46 mm filter diameter.
But it can be something other than a TZ-4. The 2" Research Grade TZ-3 Telecentric System (3x focal length) (#2459257 ) 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 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 waiting for and first becoming familiar with H-alpha observation with the TZ-3. Later, one will surely need both systems (RG-TZ-3 and RG-TZ-4) and stop down the telescope aperture as required.
Only AFTER the H-alpha etalon you can extend the field size by reducing the f-ratio by 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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