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

Telecentric with a generously dimensioned entrance aperture with a negative lens group, 2" (50.8 mm) threads on both sides – includes a T-2 adapter and 2" female/female reversing ring as standard.
46 mm free aperture connected to the H-alpha filter, making it suitable for SolarSpectrum Research Grade filters.
Extra-long working distance of 250 mm for optimized focal length reduction with telecompressors or for binocular observation.
Aplanatic, with 3x focal length extension and free of field curvature – delivers f/30 on telescopes with f/10.
Specially calculated and manufactured for the H-alpha wavelength, with 99% Strehl (99% definition brightness at 656.3 nm) depending on the telescope system used.
Even with Calcium-K (396 nm), it still delivers diffraction-limited imaging with approximately 80% Strehl.

Baader Telecentric Systems for Focal Length Extension
To create a parallel image Beam path and sufficient backfocus when used with SolarSpectrum H-alpha filters

Starting with an aperture ratio of f/15 (2x telecentric), f/10 (3x telecentric), or f/7.5 (4x telecentric), a TZS creates a parallel beam path with an aperture ratio of f/30 at full telescope aperture. For faster telescopes, the aperture should be stopped down to a final ratio of 1/30. The distance to the camera sensor from the lens vertex is 200mm for the TZ-2, 230mm for the TZ-4, and 250mm for the TZ-3. This leaves enough space behind the TZS for the H-alpha filter and any accessories, e.g., a 2" diagonal mirror or any conceivable camera equipment. The optical calculations and coatings are calculated for the H-alpha wavelength. The TZ-3 system is still diffraction-limited with over 80% Strehl even at Calcium-K (396 nm).

Please see the PDFs under the "Downloads" tab for further information.

IMPORTANT NOTE

TZ systems are essential for the function of solar spectrum filters.

Please note that for H-alpha observation below 1 Ang FWHM, a telecentric lens is absolutely necessary to achieve the recommended focal ratio of f/30 to (preferably) f/40! Only a telecentric lens can achieve the perfectly parallel beam path that is essential for the unrestricted function of such a complex etalon.

This is a MANDATORY requirement. A telescope could also be adjusted optically—or using a Barlow lens—to an aperture ratio of f/30, but this by no means means that a parallel beam path will be achieved. However, a slightly conical beam path at f/30 would only deliver the same contrast with an etalon with a 0.5 Ang FWHM as if the filter had a passband width (FWHM) of 0.7 Ang or even worse.

It doesn't necessarily have to be a TZ-4. The new 2" Telecentric System TZ-3 Research Grade (3x focal length) (#2459257, €445) is optically much better than the 20-year-old TZ-4. It therefore makes sense to start with a TZ-3 RG, for example, and stop down the telescope aperture to f/30. This maintains much better contrast 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 longer term, a newly designed, large RG TZ-4 is in preparation – it's worth waiting for it and familiarizing yourself with H-alpha observations with the TZ-3. Later on, you will certainly need both systems (RG-TZ-3 and RG-TZ-4) and stop down the telescope aperture as needed.

Only AFTER the H-alpha etalon is it possible to obtain the image obtained with the new Research Grade Telecompressor 0.4 expands the field of view

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

Technical Specifications
2" Telecentric System TZ-3 Research Grade (3x Focal Length)

Item Number
2459257
External Connection (Eyepiece/Camera Side)
M42 x 0.75 (T-2)
2"/SCT Thread (50.8mm)
External Connection (Telescope Side)
2"/SCT Thread (50.8mm)
Focal Length Extension
3x
EAN Code
4047825035332
Manufacturer
Baader Planetarium
Internal Connection (Telescope Side)
M42 x 0.75 (T-2)
Net Weight (kg)
0.21