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Declining Quality of Premium Optical Glass

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#26 mgwhittle

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Posted 21 November 2012 - 03:09 PM

Tanveer,

I think AP hasn't sold any of the Riccardi-Honders astrographs in almost two years. They certainly aren't currently making any right now. I believe Roland said the next run of telescopes would be more in the 130mm range. So maybe there is a problem with large blanks of BK7?

#27 ValeryD

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Posted 21 November 2012 - 03:55 PM

The fluorite doublet is not coming back.


Exactly opposite. But not small ones. 165mm and up.
Right now you can buy one. 7" F/8.

#28 jrbarnett

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Posted 21 November 2012 - 04:08 PM

Noted. I'll correct my statement.

"The relatively affordable fluorite doublet is not coming back."

:grin:

Incidentally, why no smaller ones?

- Jim

#29 ValeryD

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Posted 21 November 2012 - 04:09 PM

maybe there is a problem with large blanks of BK7?


Yes, true.

#30 TG

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Posted 21 November 2012 - 05:13 PM

maybe there is a problem with large blanks of BK7?


Yes, true.


Details would be great, Valery. Russian glass? Chinese glass? Japanese glass?

#31 M13 Observer

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Posted 21 November 2012 - 05:31 PM

Noted. I'll correct my statement.

"The relatively affordable fluorite doublet is not coming back."

:grin:

Incidentally, why no smaller ones?

- Jim


I think you stated the reason yourself. Relatively affordable is a term denoting different things to different people but a common thread when hearing it is "cheap". Cheap and fluorite are terms which can no longer be used compatibly in the same sentence. Also, even it it was "relatively expensive", the market for small high quality refractors is, how shall we describe it, "limited" meaning low profit margins combined with low sales = no production.

#32 chboss

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Posted 22 November 2012 - 02:30 AM

Noted. I'll correct my statement.

"The relatively affordable fluorite doublet is not coming back."

:grin:

Incidentally, why no smaller ones?

- Jim


I beg to difer....
How about the Tak FC-76? ;)

regards
Chris

#33 jrbarnett

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Posted 22 November 2012 - 10:04 AM

I did specify "affordable"...:lol: (IMO, the FC-76 is quite expensive (as in overpriced) for what it is, especially compared to the retail pricing of the original FC-76 and the FS-78.)

In the heyday of the FS-series, for example, you could buy the FS-78 for about $1000, the FS-102 for about $2000, the FS-128 for about $3500 and the FS-152 for about $6000. In each of those apertures, by today's standards, you can't find anything close. You either buy Chinese Frankescopes cobbled together by a mad-scientist-brander for a similar price, or you pay through the nose for anything "premium" of like aperture. Heck, some of the Chinese 5" and 6" scopes actually cost *more* than the FS-128 and FS-152!

I can't tell you how many times I've kicked myself for not picking up an FS-152 when it was available.

Regards,

Jim

#34 Yu Gu

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Posted 22 November 2012 - 11:17 AM

Sounds like QE never happened..
A Synta 120ed is actually a better deal then either FS-102 or FS-128.
Maybe you will kick yourself again 10 years later...

#35 jrbarnett

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Posted 22 November 2012 - 11:35 AM

"A Synta 120ed is actually a better deal then either FS-102 or FS-128."

First off, it's "than" not "then", "professor".

Second,...

:roflmao:

That was a *very* good joke!

http://www.astro-for...-APO&p=30242...

http://www.astro-for...102-und-TMB-...

Know any more howlers?

There is indeed some kicking going on, but it's not me kicking myself in this case.

Rather, it's Takahashi hand figured fluorite doublets doing the kicking, and the target is the backsides of mass-market, CNC ground and polished, optics being passed off at premium prices to unsuspecting buyers. :winky:

Are the Synta scopes P.T. Barnum endorsed? :grin:

- Jim

#36 Yu Gu

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Posted 22 November 2012 - 12:05 PM

Again, I am waiting on a referece for "hand figured" and "CNC ground and polished"

#37 M13 Observer

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Posted 22 November 2012 - 07:02 PM

Again, I am waiting on a referece for "hand figured" and "CNC ground and polished"


Astro-Physics, TEC, LOMO

#38 Sky Muse

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Posted 23 November 2012 - 12:11 AM

"Some other telescope manufacturers use Takahashi refractors as collimating instruments for larger telescopes." - WIKIPEDIA

Alan

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#39 M13 Observer

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Posted 23 November 2012 - 12:34 AM

"Some other telescope manufacturers use Takahashi refractors as collimating instruments for larger telescopes." - WIKIPEDIA

Alan


Actually Canon makes the lenses for Takahashi telescopes which is why I did not include Takahashi in the list. The other three I listed do all their figuring in-house. Another one I have left out is Zeiss. They used to do all their own stuff but are outsourcing a lot of it these days. As well, they no longer build telescopes. I own a couple of Zeiss microscopes and both were built in-house prior to the outsourcing. I hope their QC is still in place to ensure high quality optics.

As to the Takahashi Collimating Telescope, it is a special purpose and fairly small telescope used specifically for collimating purposes and has absolutely nothing directly to do with "hand figuring".

#40 Sky Muse

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Posted 23 November 2012 - 12:49 AM

Mine was only a general posting right afterwards. :)

"As well, they no longer build telescopes."

If only Zeiss would reconsider, and their oculars in addition.

Regards,

Alan

#41 MrGrytt

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Posted 23 November 2012 - 01:27 PM

"Some other telescope manufacturers use Takahashi refractors as collimating instruments for larger telescopes." - WIKIPEDIA

Alan


Another one I have left out is Zeiss.


You also left out LZOS.

Harvey

#42 carlcat

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Posted 23 November 2012 - 02:16 PM

So, are we looking at the next wave of new refractors in the 4-6 inch range as fpl-51 triplets? Are the Orion Eons gone forever? I was kinda thinking of getting the 120 Eon some time down the line, may not happen?

#43 ValeryD

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Posted 24 November 2012 - 03:08 AM

Details would be great, Valery. Russian glass? Chinese glass? Japanese glass?


No information for public about glasses source available.

And we will try to make them affordable, at least more affordable than present apo telescopes.

We moving ahead, but much slower than we expected. However, after the first samples tests, we can increase the speed. Right now our plan is to create the new line of larger APO fluorite doublets with minimal investments in the project. Therefore the slow speed.

The only info available at this moment:

1. They will be fluorite doublets.
2. No false colors whatsoever - nor in focus, nor outside of focus
3. No any liquid inside.
4. User adjustable lenses centration.
5. 4" havy-duty two speed 1:10 focuser
6. Rotation finder position.
7. 178mm F/8.5 - the first model (in full progress).


Valery.

#44 ed_turco

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Posted 24 November 2012 - 11:55 AM

A bit off topic, but here goes. I see your concerns, but these rumors about BK 7 being not so hot are probably not true. The optical industry NAILED this glass down tight in production procedures and annealing. Grade A is so good, that grade B is often more than good enough. I know, I used Grade B.

Small point, maybe.

#45 ValeryD

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Posted 26 November 2012 - 01:06 AM

"Some other telescope manufacturers use Takahashi refractors as collimating instruments for larger telescopes." - WIKIPEDIA

Alan


Absolutely nonsense!

#46 MrGrytt

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Posted 26 November 2012 - 07:21 AM

Maybe someone has a distorted idea of what a Takahashi collimation scope is.

Harvey

#47 Starhawk

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Posted 26 November 2012 - 09:14 AM

What's going on is the iPhone and its ilk are using all the glass the large primes can make- it pays well, and the yield levels are very high for small blanks (yield drops with the cube of size).

They support the camera makers, whose largest blanks are 150mm, usually. So, Roland can keep 130s in continuous production. Bigger stuff won't be easy. Yuri said Prettymuch the same thing. At ASAE, he was showing a pair of beautiful RCs from his shop. The faster one was f/5.6. So, that's where he is exploring.

-Rich

#48 JohnH

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Posted 26 November 2012 - 11:07 AM

I think Yuri said that the glass for the miniscus was getting incredibly expensive and he did not feel that there was a sufficient interest in an expensive Mak.


The first part doesn't seem right as the meniscus is just BK7, the cheapest optical glass on the planet.

The second part I can agree with as Maks appeal to a limited segment except when it's the A-P Mak in which case everybody wants one.

Tanveer.


Now I don't feel so bad hoarding Maksutov corrector blanks.

#49 Sky Muse

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Posted 26 November 2012 - 03:46 PM

http://en.wikipedia....ashi_Seisakusho

If taken for its word, "some" use Takahashi, the glass being either of calcium fluorite crystal or ED. The article did not specify. It's possible that Wikipedia confused the refractors for the collimator...

http://www.optcorp.c...px?pid=138-7123

...?

Alan

#50 MrGrytt

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Posted 26 November 2012 - 09:53 PM

I suspect you're correct about that. The description of the collimation scope is a little misleading.

Harvey






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