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Zeiss Jena has risen from the grave

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#76 25585

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Posted 30 December 2019 - 12:15 AM

APM have some Zeiss scopes for sale http://apm-telescope...tegory/31383935



#77 Piggyback

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Posted 04 January 2020 - 06:02 AM

Does "APQ" stand for anything?  Is it an acronym?

 

Thank you.

According to a dealer who talked to Dr. Pudenz (man in charge for development of the Zeiss APQ) AP stands for Apochromat and Q is an acronym for liquid.



#78 Heywood

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Posted 04 January 2020 - 09:39 AM

According to a dealer who talked to Dr. Pudenz (man in charge for development of the Zeiss APQ) AP stands for Apochromat and Q is an acronym for liquid.

 

Are the APQ's oil-spaced???



#79 Astrojensen

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Posted 04 January 2020 - 10:16 AM

Are the APQ's oil-spaced???

Yes.

 

 

Clear skies!
Thomas, Denmark



#80 Uwe Pilz  Happy Birthday!

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Posted 04 January 2020 - 01:12 PM

The old APQs had fluorite lenses, I don't know whether this is / will be still the case. Today, glasses with a high fluorite content are used. 

 

Glasses can be grinded to nearly every accuracy. This is not possible for a crystal, fluorite is a crystal. There always remain steps in the surface form the crystal structure.

 

The oil has a similar diffraction coefficient like the fluorite and the glasses among it. It smears up the remaining inaccuracy of the fluorite lens.


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#81 denis0007dl

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Posted 04 January 2020 - 01:52 PM

The old APQs had fluorite lenses, I don't know whether this is / will be still the case. Today, glasses with a high fluorite content are used. 

 

Glasses can be grinded to nearly every accuracy. This is not possible for a crystal, fluorite is a crystal. There always remain steps in the surface form the crystal structure.

 

The oil has a similar diffraction coefficient like the fluorite and the glasses among it. It smears up the remaining inaccuracy of the fluorite lens.

When we talk about oil in Zeiss APQ, over the years, very often, it show very bad looking delaminations clearly visible to any person at daytime.

 

In some tests showed, these oil delaminations between lenses, Strehl number and overall optical performance decrease.



#82 Uranotopia

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Posted 05 January 2020 - 02:44 AM

Thought  Thomas Baader does already the Zeiss amateur astronomy instruments service by contract with Carl Zeiss Jena. In other words there is already a relation between Zeiss and Baader or, if you want between Baader and Zeiss.

 

Source:  https://www.baader-p...ompany-history/

I can remember, that the older Baader filters (colour filters and also for instance the socalled "contrast booster") were initially produced in Jena by Carl Zeiss optics. Later the have been produced by "Baader", but I couldn't find informations, where the filter factory was located or where Baader produces the fikters now... . perhaps Baader bought a part of Carl Zeiss Jena's company years ago?!?


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#83 opusone

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Posted 05 January 2020 - 04:23 AM

Just curious..

 

 

Would you buy an APQ 200(complete system for both visual and AP)

 

or

 

A high end 20" Dobsonian(NMT, Teeter, etc) and

a high end portable AP rig(Telescopi Italiani TI35, Officina Stellare RiFast300, etc)?

 

 

I'd go for the latter, but I also would like to hear from people who would choose the former.



#84 Astrojensen

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Posted 05 January 2020 - 04:42 AM

Just curious..

 

 

Would you buy an APQ 200(complete system for both visual and AP)

 

or

 

A high end 20" Dobsonian(NMT, Teeter, etc) and

a high end portable AP rig(Telescopi Italiani TI35, Officina Stellare RiFast300, etc)?

 

 

I'd go for the latter, but I also would like to hear from people who would choose the former.

An extremely complex question with as many answers, as there are amateur astronomers. Literally. 

 

Firstly, a 200mm APQ is going to be WILDLY more expensive than a high end 20" dob, probably approaching the cost of a high end 40" or even 50", if you take the cost of the mount for the APQ into consideration, but it's also a very, very different instrument and has strengths in fields the dob can't even operate in, such as solar H-alpha.

 

Similarly, a smaller, portable rig is superior to the APQ, if the APQ can't be mounted under dark skies and the user wants to observe very faint, extended deep-sky objects. 

 

So what one would take should depend entirely on personal preferences. There can't be no clear winner, because the instruments are so radically different and cater to different uses and purposes and as such, the question becomes meaningless. 

 

 

Clear skies!
Thomas, Denmark


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#85 SandyHouTex

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Posted 05 January 2020 - 12:28 PM

The old APQs had fluorite lenses, I don't know whether this is / will be still the case. Today, glasses with a high fluorite content are used. 

 

Glasses can be grinded to nearly every accuracy. This is not possible for a crystal, fluorite is a crystal. There always remain steps in the surface form the crystal structure.

 

The oil has a similar diffraction coefficient like the fluorite and the glasses among it. It smears up the remaining inaccuracy of the fluorite lens.

I’m confused by your 2nd statement on glass versus fluorite steps.  If true, why is it used to make optical surfaces accurate to millionths of an inch,

 

Do you have a reference for this?


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#86 j.gardavsky

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Posted 05 January 2020 - 12:31 PM

I can remember, that the older Baader filters (colour filters and also for instance the socalled "contrast booster") were initially produced in Jena by Carl Zeiss optics. Later the have been produced by "Baader", but I couldn't find informations, where the filter factory was located or where Baader produces the fikters now... . perhaps Baader bought a part of Carl Zeiss Jena's company years ago?!?

The contrast Booster glass comes from SCHOTT BG20, and from its variants. Baader puts on it the multicoatings.

The Zeiss (and some of the Baader) color filters come again from SCHOTT, the rest are the replacement color glass materials from the Far East.

The single line (like nebular) filters, and the dichroic (like UHC) filters have been the first time series manufactured by Balzers in Liechtenstein)* for the Zeiss applications to microscopy and astronomy, later labelled by Zeiss)*, and also made for the optics testing.

 

According to Thomas Baader, the Baader interference filters for the astronomy are manufactured in Germany, and most probably with the Leybold Optics thin layer deposition technologies, now the Swiss-German Bühler-Leybold, https://www.buhlergr...m/leyboldoptics

 

)* Historical samples of these are in my collection.

 

Best,

JG


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#87 Uwe Pilz  Happy Birthday!

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Posted 06 January 2020 - 12:51 AM

>> Glasses can be grinded to nearly every accuracy. This is not possible for a crystal, fluorite is a crystal. There always remain steps in the surface form the crystal structure. The oil has a similar diffraction coefficient like the fluorite and the glasses among it. It smears up the remaining inaccuracy of the fluorite lens.

 

> I’m confused by your 2nd statement on glass versus fluorite steps.

 

A crystal is not a glass. It has its own crystal structure and tends to break at the crystal boundaries which causes a step like surface structure. May be with modern technology it is possible to grind t down to the level of normal lenses, at least for smaller sizes.

 

I tried to find a reference and eventual I found one, but it is very outdated. I hope the link works. The article

 

Apochromatic photographic aerial lenses and other optical instruments making use of synthetic fluorite (Dec 31, 1945)

 

contains a section about a 6 inch fluorite lens. Here you may read the sentence

 

 

All lenses made so far have been cemented between other glass elements, so that surface defects have been tolerable.


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#88 donadani

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Posted 06 January 2020 - 03:46 AM

Hi Uwe,

 

what about all the fluorite doublets made by Vixen and Takahashi in the 80ies, 90ies and up to today... no oil between the lenses but perfect optics. Or do you mean these problems only for < f/7 ?

 

Today AOM and TEC do oil filled fluorite doublets and I never heard they use glases "with fluorite" I only heard they use real fluorite blanks... Well who really knows... - all companies get these blanks from Japan - so who really knows what is inside...? 

 

But finally who cares - their results are outstanding!

 

cs

Chris


Edited by donadani, 06 January 2020 - 05:09 AM.


#89 Uwe Pilz  Happy Birthday!

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Posted 06 January 2020 - 08:11 AM

> I never heard they use glases "with fluorite"

 

These are glasses with fluorphosphate. FPL-53 is such a thing.



#90 garret

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Posted 06 January 2020 - 10:48 AM

 

These are glasses with fluorphosphate. FPL-53 is such a thing.

FPL-53: with fluorite but not single crystal like CaF2 ?



#91 APQ JENA

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Posted 06 January 2020 - 11:02 AM

Here it was said that the focal length of the 150/1200 would be too long. However, according to the voting results so far, most voted for the f/8:

https://apq.de/en/po...s.htm?tab=2#tpl

We can also realize much faster aperture ratios. The 150mm Polychromat has a polychromatic Strehl of 0.96 at f/5.6:

https://apq.de/en/op...n.htm?tab=8#tpl

Norbert

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#92 Fomalhaut

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Posted 06 January 2020 - 11:04 AM

FPL-53: with fluorite but not single crystal like CaF2 ?

 

FPL53 is optical glass improved with fluorophosphate, yes.

But not pure (artificially grown) crystal such as CaF2.

 

The 27 years old fluorite lens in my air-spaced Tak FCT-triplet is well protected because sandwiched between 2 glass-lenses and still doesn't show any stray-light. Even in the strongest flahlight it still looks as virgin as ever.

 

IMO, it is a good idea to use CaF2, if not sandwiched then as the 2nd lens in a Steilhein-design such as all old and new Tak FCs (and other than Tak "Fraunhofer" FSs).

 

As for oil-spaced triplets, I remember very-well an AP-150 with an oil-leak of about 50% (...of its oil missing).

In this state, it was ridiculously left in the dust by my much smaller FCT100 standing "next door".


Edited by Fomalhaut, 06 January 2020 - 11:59 AM.

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#93 donadani

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Posted 06 January 2020 - 12:49 PM

I think AOM, TEC, Canon (Takahashi & Vixen), Agema and earlier Zeiss used and still use artificially grown crystal (CaF2) and that it is no problem with or without oil and as front or as back lens - if one knows how to, has the right machines and coating technology... 

 

Regarding APQ Jena - I would be more interested in the question if there are any orders right now and if yes if it´s possible to get some pics of the manufacturing process and the final product here or on the homepage?


Edited by donadani, 06 January 2020 - 12:59 PM.


#94 SandyHouTex

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Posted 06 January 2020 - 03:34 PM

So I did some research.  Fluorite, CaF2, is grown artificially in the lab.  When complete, it is one solid crystal.  Not a collection of many crystals:

 

https://www.spiedigi...614.short?SSO=1

 

I couldn't really find much on the actual micro-surface after polishing, but I would suspect that it is just as good as regular glass, and, no bubbles.  That's why when you shine a laser at a Fluorite lens, you can't see it pass through the lens.  With glass, there are always micro-bubbles which reflect the laser light, so you can see it's passage. 



#95 Uwe Pilz  Happy Birthday!

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Posted 07 January 2020 - 12:49 AM

> Fluorite, CaF2, is grown artificially in the lab.  When complete, it is one solid crystal.  Not a collection of many crystals:

 

Of course. But glass is amorphous and a crystal fluorite has an internal structure. In the case of CaF2 it is hexagonal, that means cubic (like kitchen salt). It tends to break along this cubic structures. Glass does not have any internal structure and does not have a tendency to break in any Intrinsic way.

 

In the meantime, I read more about it. It seems so, that we have technology  now that masters the problems with grinding CaF2 crystals, so it is possible to produce flawless lenses. It may be, however, that Zeiß Jena maintained an older technology.


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#96 APQ JENA

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Posted 07 January 2020 - 06:08 AM

> Regarding APQ Jena - I would be more interested in the question if there are any orders right now and if yes if it´s possible to get some pics of the manufacturing process and the final product here or on the homepage?

Yes there is. And the pictures are here (5 pieces):

https://apq.de/en/optics_mfg.htm

Norbert



#97 mikeDnight

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Posted 07 January 2020 - 07:36 AM

I’m confused by your 2nd statement on glass versus fluorite steps.  If true, why is it used to make optical surfaces accurate to millionths of an inch,

 

Do you have a reference for this?

I was confused also. Calcium Fluorite optics are a mono Crystal grown under strict laboratory conditions and are essentially perfect, having no flaws or steps of any kind. Below is from the TAKAHASHI FC100DC user manual. 

 

IMG_3943.JPG


Edited by mikeDnight, 07 January 2020 - 07:41 AM.


#98 mikeDnight

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Posted 07 January 2020 - 08:02 AM

Kowa shed a little more light on the qualities of Fluorite crystal vs fluorite glass.

Screenshot_2020-01-07-13-03-49.png


Edited by mikeDnight, 07 January 2020 - 08:03 AM.

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#99 opusone

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Posted 07 January 2020 - 09:32 AM

When will the 180mm model be produced and how much will it be?

#100 vahe

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Posted 07 January 2020 - 11:07 AM

When will the 180mm model be produced and how much will it be?

In the world of high end doublets and triplets 180's are priced at about double the price of a 150, I do not see why it would be any different with this offering.

.

Vahe




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