Baader Triband SCT

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bart1805
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Baader Triband SCT

Post by bart1805 » Sun May 06, 2018 5:38 pm

Baader announced the prices of their Triband SCT's yesterday.
3.275 euro's for the 8 inch version.
Clear skies, Bart.

https://www.baader-planetarium.com/en/t ... p-sky.html

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Re: Baader Triband SCT

Post by TheSkyBurner » Sun May 06, 2018 9:55 pm

neat but way too much money for what it is.

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Re: Baader Triband SCT

Post by Merlin66 » Mon May 07, 2018 12:09 am

Skyburner,
What cheaper full aperture multi-wavelength filters have you come across?
These filters are very effective.
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Re: Baader Triband SCT

Post by TheSkyBurner » Mon May 07, 2018 8:16 am

Merlin. Just order direct from schott glass co. They make upto 300mm to your spec.

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Re: Baader Triband SCT

Post by TheSkyBurner » Mon May 07, 2018 8:32 am

Oh wow, they are up to 400mm custom sizes now, thats new!
https://www.us.schott.com/advanced_opti ... index.html

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Re: Baader Triband SCT

Post by christian viladrich » Mon May 07, 2018 4:44 pm

Skyburner, I suggest you ask Schott a quote for one 220 mm ERF lambda/4 P-V.
Once you have the answer, you might have a different appreciation ;-)
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Re: Baader Triband SCT

Post by TheSkyBurner » Mon May 07, 2018 7:39 pm

I already know the answer :) but I cannot share it due to confidentiality agreement.

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Re: Baader Triband SCT

Post by mdwmark » Tue May 08, 2018 7:49 am

Hi Group,
I've seen Schott's ERF. But not a 220mm one, it might have been 160mm. They take an thin RG630 and laminate it to a coated bandpass. The one at the show was about 4mm thick. I asked how it would keep the 1/4 wave they clam, if it was in the heat. The problem I have with this idea is that I have seen laminated part fail with heat. Also over the years I have come across a lot RG630 that would not hold up optically in large sizes. This is why Baader's ERF's are no longer on RG630 but BK7.
I don't know how it could cost less in a small batch of one. Just the coating run could cost $5000 with out the glass.
Mark W.

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Re: Baader Triband SCT

Post by TheSkyBurner » Tue May 08, 2018 8:33 am

Not true at all mdwmark. Ive seen countless people claim things cannot be done but then it gets done. Its $800 for a single 90% transmission 1nm filter with od 6 blocking from deep uv to far infrareds 48mm in diameter premounted in astrocell. With 1/10th wave at 40/20 scratch and dig at 6mm thick on uv substrate. It doesnt get much better than that spec Companies do this 24 hours a day with single orders. Batche orders are 30% cheaper. Schott glass gives a substantially lower price on a batch of just tw, and they are not laminate or epoxied.They are dielectric single sided or double sided bandpaass. I cant say anymor, but there are already people selling these things for profit on the side. The cost of a 200mm filter is way cheaper than you think, look at the baader 170mm derf filter. You just gotta know who to talk to! Give schott an email and find out first hand, but you cannot share the details without breaking the confidentiality agreement.

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Re: Baader Triband SCT

Post by christian viladrich » Tue May 08, 2018 1:36 pm

I am just wondering whether we are talking of the same things ?

ERF are large band filters (50 to 150 nm FWHM) centered on Ha and (usually) installed in front of the aperture of the telescope. The optical quality should be OK (better than L/4 P-V).
They become very expensive when aperture increases.There are two reasons for that :
- optical flats windows (typically BK7)are very expensive,
- the process of coating is very expensive.

Mark gave a 5000 USD for a coating run.

This assumes that the coating process is already tuned to what is expected . Usually, it takes several coating tests to succesfully tune the coating process to what is expected. Depending on how many units of ERF you want, you have to pay for the coating test runs or not.

Futhermore, the size of the vacuum chamber is limited. It maybe be that it can accomodate 6 x 200 mm ERF, but only one 300 mm ERF. So the cost of the coating run increases drastically when the size of the ERF increases.

Presently, the largest ERF are made by Aries (about 14") and Baader (280 mm). This being said, it would be nice to have another provider there (further to Aries, Baader, Beloptik and AiryLab).
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Re: Baader Triband SCT

Post by bart1805 » Tue May 08, 2018 9:47 pm

Skyburner, I am a bit confused. I know the price of a 160 mm Baader Erf because I payed for one: 995 euro without a cell. But the filter you describe is 48mm, with a price of 800 dollar. And it is 3.250 euro for a 8 inch Celestron Edge HD telescope with a Triband-ERF-coated Schmidt corrector plate. That includes the scope. What am I missing that makes Schott cheaper? Thanks! Bart.

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Re: Baader Triband SCT

Post by TheSkyBurner » Wed May 09, 2018 3:28 am

:)

My example of 48mm mounted astronomical grade filter with 1nm of FWHM and od6blocking with 90% transmission is the absolute highest grade filter you can get.

Wideband / triband filters require are very low grade coating process that has been established and designed for high volume production.

astronomical grade Optical glass of 200mm diameter is nothing special and nothing new.


While it is true that size of the vacuum chamber is a issue, it is only a problem to a company that has a small machine that deals with single order clients that will only ever order one product, but to a mass production facility with high volume capability like semrock.com it is a piece of cake.

Schott is a high volume facility, and they discount heavily on a batch of only TWO. 100mm, 200mm, 300mm doesnt matter.

What matters is the level of advanced coating, and a wideband filter that is 30nm FWHM is not advanced at all and not complicated, and very simple to produce even at 200mm.


But in the end, the average person is just going to buy the premade prefab telescope and not make a custom filter.

It is possible however. The baader sct is cool, but its nothing special. AIRYLAB has produced one for a few years now, and they probably just outsourced their product to baader planetarium with a different corrector. (just speculation)


I cant say the same about the aries derf because company secrets are just that. secrets.

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Re: Baader Triband SCT

Post by Valery » Wed May 09, 2018 7:02 am

christian viladrich wrote:
Tue May 08, 2018 1:36 pm


Presently, the largest ERF are made by Aries (about 14") and Baader (280 mm). This being said, it would be nice to have another provider there (further to Aries, Baader, Beloptik and AiryLab).
I can only confirm, that custom made large DERF filters with necessary precision are expensive. We are somewhat less expensive because of labor, electricity etc cost here (Ukraine) are not as high as in the EC countries or in the USA.
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Re: Baader Triband SCT

Post by Astrograph » Fri May 11, 2018 11:47 am

Speaking as both an Airylab and Baader Solar reseller, I can assure you that Frederics (Airylab) product is nothing to do with Baaders and its a lot harder to do all this than is being suggested. Low PV maybe but not L4+. It is also easy to see the difference visually between an L4 Glass ERF and an L10 D-ERF. L4 is also L4 what? Glass, Transmission? The filter could be L10 on both sides but if the sides are not parallel, transmission might only be L2.

I know Airylab have experienced lots of pain getting reliable coating and ERF's manufactured. I'm sure Valery has too. You get what you pay for.

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Re: Baader Triband SCT

Post by fjabet » Fri May 11, 2018 12:26 pm

Yes, pretty painful as you mentioned Rupert :)

I did get exchange with Schott Yverdon factory at a time as I know people there. They would make the 200 or 235mm flat windows L/8 at a quite decent price (that is already 4 digits in €, and that was before the swiss Franc increase). But they won't do the coating for such a large size with the quality metric I was asking for (ie less than 10% inhomogeneity, plus a >80% transmission in the Ha band).

Making those ERF get very difficult on a large size because of the inhomogeneity issue. If you have too much difference in term of transmission that causes the same issue as an optical default. Actually making a FFT of the intensity map give an idea of the induced PSF.

BTW, Baader are stad SCT, not edge HD, and have nothing to do with Airylab beside taking over the idea.
And I don't have to remind that making CaK with a SCT is just not possible due to spherochromatism.

Honestly, SkyBurner, what you say is just not credible.
Last edited by fjabet on Fri May 11, 2018 4:01 pm, edited 1 time in total.
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Re: Baader Triband SCT

Post by bart1805 » Fri May 11, 2018 1:44 pm

fjabet wrote:
Fri May 11, 2018 12:26 pm
BTW, Baader are stad SCT, not edge HD
Thanks for clearing that up, my mistake. Thought I had read somewhere they used the Edge.

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Re: Baader Triband SCT

Post by Astrograph » Fri May 11, 2018 1:53 pm

An easy mistake as the scope is not black.

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Re: Baader Triband SCT

Post by christian viladrich » Fri May 11, 2018 4:44 pm

I've completly missed the fact that the Tri-band is not an Edge-HD :

Image

BTW, my 210 mm AiryLab ERF is L/10 P-V :-)
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Re: Baader Triband SCT

Post by fjabet » Fri May 11, 2018 8:11 pm

And your C8 also :)
I didn't notice that Baader ray tracing is very wrong. At the entry those are the chief and marginals rays, at the exit its a mixed of chiefs rays or standard rays. Actually we could even believe that the system use an afocal rather than a telecentric, and that the last lens that is supposed to be a reducer is converging the beam. I think that the guy who did the drawing was not really into optics...
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Re: Baader Triband SCT

Post by Astrograph » Fri May 11, 2018 10:40 pm

But its pretty. It has colour and arrows and stuff.....

Do you think when they did the three colour TRI part of the logo it was the same person? Purple for Calcium. Yep. Red for Ha. Yep. Yellow for Continuum, err. Ah but of course, the Sun's yellow :)

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