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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?
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)
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)
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)
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,
Mikhail
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,
Mikhail
Question by: Mikhail on Nov 27, 2018 6:38:00 PM | 1 Answer(s)
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?
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)
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)
- Description
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Details
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
IMPORTANT NOTE
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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The benefits of telecentric systems
Telecentric System or Barlow Lens? A Barlow lens is the best-known way to change the focal length and thus the focal ratio of a telescope. A telecentric system is similar to a barlow, but also contains an additional positive lens element. This makes it possible to change the focal length of the telescope and to achieve a parallel beam of light. For most applications, therefore, a barlow lens is fine; but especially in connection with narrow-band interference filters (as for solar observation in H-alpha), the more complex construction of a telecentric system is absolutely necessary. However, both systems have their own advantages To understand the differences, you must first understand: The position of an image point depends on how far it is away from the centre of the image. With a Barlow lens, the distance increases with the extension factor, so the image is "blown up" after the Barlow. With a telecentric, all the magnification is done purely within the telecentric system, so the light rays remain parallel and do not diverge outwards. This has some effects in practice. One of the noticeable properties of a Barlow lens is that it extends the eye relief of an eyepiece, as it...
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An experience report on the new Baader Telecentric System TZ-3 and the Research Grade (RG) Telecompressor (TC) 0.4
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First Class H-alpha Solar Filters by SolarSpectrum
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Additional Information
| Manufacturer | Baader Planetarium |
|---|---|
| SKU (#) | 2459257 |
| EAN Code | 4047825008695 |
| Net weight (kg) | 0.21 |
| Focal length extension | 3x |
| Usage | for H-alpha observation with SolarSpectrum filters |
| Inner Connection (lens sided) | Thread, T-2 (M42 x 0,75), 2" (50,8mm) |
| Outer Connection (lens sided) | Thread, 2" (50,8mm) |
| Outer Connection (eyepiece/-camera-sided) | Thread, T-2 (M42 x 0,75), 2" (50,8mm) |
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