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Equipment Discussions >> Refractors

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Eddgie
Postmaster
*****

Reged: 02/01/06

Re: Declining Quality of Premium Optical Glass new [Re: 10gauge]
      #5531405 - 11/21/12 12:40 AM

These kinds of questions come up from time to time, and without being in the business, you may never know the facts.

That means that I get to guess.

First, it isn't just the amount of something that is available (someone said BK7 is plentyful), but rather the amount of something that is suitable for the desired purpose.

And most people don't need 200mm x 80mm thick blocks of optical quality BK7.

And when no one is in line to buy a couple of thousand blanks of optical quality BK7, you take your giant furnace that costs tens of thoushands of dollars a month in energy to keep hot and you make stuff that people order by the pallate.

In business, it is always about profit and even if you get several hundred to several thousand dollars for a blank, these days, you will struggle to pay the energy bill if someone only want 20 of them.

But if you can make 10,000 small blanks for use in lenses and other small optics, then even though you don't make as much profit on each one, you make more money because of the volume.

While we can't know the exact reason, you can bet that it is the economics of it.

But if you place an order for 10,000 large BK7 blanks, I bet someone will make them for you.

But not a couple of dozen that a botique telescope maker might consume in a year.

Any time you see a question like this, remind yourself that big refractors are a very specialized and tiny market. No one is going to cater to it if they can make more money running their giant glass melting facilities to fill giant orders for other kinds of glass.


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vahe
professor emeritus


Reged: 08/27/05

Loc: Houston, Texas
Re: Declining Quality of Premium Optical Glass new [Re: 10gauge]
      #5531614 - 11/21/12 07:32 AM

Quote:

Why are prices for premium glass expanding faster than the universe? The chemistry hasn't changed much,





Chemistry is in fact one of the main reasons, environmental rules and restrictions play a major role in availability, what was once an easy solution is no longer permitted.

Vahe


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: 10gauge]
      #5531905 - 11/21/12 10:38 AM

Quote:

Why are prices for premium glass expanding faster than the universe? The chemistry hasn't changed much, contrary to the fact that production techniques have improved and should have become cheaper over the years. Is it demand, labor, raw materials, facilities, or is it simply because that people will pay for such premium glass?




As Vahe said:

Check out post #19837 on tec-ug.

If you can't read it, the succinct summary is that Yuri has quite a number of what initially "look" to be excellent pieces of said glass in sizes up to 12.5" sitting on a shelf. They are all useless for anything other than paperweights. This is due to the changes in the way said glass is made, changing to "environmentally friendly processes".

If you want more info, read his original post.

Edited by M13 Observer (11/21/12 10:40 AM)


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TG
Pooh-Bah


Reged: 11/02/06

Loc: Latitude 47
Re: Declining Quality of Premium Optical Glass new [Re: M13 Observer]
      #5532382 - 11/21/12 02:28 PM

Quote:

Quote:

Why are prices for premium glass expanding faster than the universe? The chemistry hasn't changed much, contrary to the fact that production techniques have improved and should have become cheaper over the years. Is it demand, labor, raw materials, facilities, or is it simply because that people will pay for such premium glass?




As Vahe said:

Check out post #19837 on tec-ug.

If you can't read it, the succinct summary is that Yuri has quite a number of what initially "look" to be excellent pieces of said glass in sizes up to 12.5" sitting on a shelf. They are all useless for anything other than paperweights. This is due to the changes in the way said glass is made, changing to "environmentally friendly processes".

If you want more info, read his original post.




Interesting but funny how Roland has never complained about BK7 (he's complained enough about FPL53). A-P currently sells a large scope with a large corrector which I suspect is BK7 and possibly the primary mirror as well is some BK7-like glass, being a Mangin mirror. I'm guessing about BK7 being the glass used in the A-P scope but most designs for the R-H astrograph I've seen here in the ATM group are BK7 based so I think my guess is probably correct. I wonder if Yuri's problem is particular to his glass supplier. In any case, it's a shame if that's what's stopping Yuri from building Maks. Maybe a corrected D-K would be more to his liking (and to mine if it's optimized for visual).

Tanveer.


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dscarpa
Post Laureate
*****

Reged: 03/15/08

Loc: San Diego Ca.
Re: Declining Quality of Premium Optical Glass new [Re: 10gauge]
      #5532403 - 11/21/12 02:38 PM

SAs the owner of a IM-715D and mak fan in general I'm with you on that. David

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mgwhittle
Pooh-Bah
*****

Reged: 08/24/11

Loc: Chattanooga, TN
Re: Declining Quality of Premium Optical Glass new [Re: dscarpa]
      #5532443 - 11/21/12 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?


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ValeryD
Vendor (Aries)
*****

Reged: 11/26/05

Loc: Kherson, Ukraine.
Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5532541 - 11/21/12 03:55 PM

Quote:

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.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Declining Quality of Premium Optical Glass new [Re: ValeryD]
      #5532561 - 11/21/12 04:08 PM

Noted. I'll correct my statement.

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



Incidentally, why no smaller ones?

- Jim


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ValeryD
Vendor (Aries)
*****

Reged: 11/26/05

Loc: Kherson, Ukraine.
Re: Declining Quality of Premium Optical Glass new [Re: mgwhittle]
      #5532563 - 11/21/12 04:09 PM

Quote:

maybe there is a problem with large blanks of BK7?




Yes, true.


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TG
Pooh-Bah


Reged: 11/02/06

Loc: Latitude 47
Re: Declining Quality of Premium Optical Glass new [Re: ValeryD]
      #5532674 - 11/21/12 05:13 PM

Quote:

Quote:

maybe there is a problem with large blanks of BK7?




Yes, true.




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


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5532706 - 11/21/12 05:31 PM

Quote:

Noted. I'll correct my statement.

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



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.


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chboss
professor emeritus


Reged: 03/24/08

Loc: Zurich Switzerland
Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5533312 - 11/22/12 02:30 AM

Quote:

Noted. I'll correct my statement.

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



Incidentally, why no smaller ones?

- Jim




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

regards
Chris


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Declining Quality of Premium Optical Glass new [Re: chboss]
      #5533646 - 11/22/12 10:04 AM

I did specify "affordable"... (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

Edited by jrbarnett (11/22/12 11:36 AM)


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Yu Gu
member


Reged: 06/18/06

Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5533767 - 11/22/12 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...


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Declining Quality of Premium Optical Glass new [Re: Yu Gu]
      #5533800 - 11/22/12 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,...



That was a *very* good joke!

http://www.astro-foren.de/showthread.php?7805-Takahashi-FS-78-APO&p=30242...

http://www.astro-foren.de/showthread.php?8591-Reife-Takahashi-FS-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.

Are the Synta scopes P.T. Barnum endorsed?

- Jim


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Yu Gu
member


Reged: 06/18/06

Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5533835 - 11/22/12 12:05 PM

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

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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: Yu Gu]
      #5534333 - 11/22/12 07:02 PM

Quote:

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




Astro-Physics, TEC, LOMO


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Sky Muse
sage


Reged: 10/26/12

Loc: De Soto County, MS
Re: Declining Quality of Premium Optical Glass new [Re: M13 Observer]
      #5534661 - 11/23/12 12:11 AM Attachment (32 downloads)

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

Alan


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5534675 - 11/23/12 12:34 AM

Quote:

"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".


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Sky Muse
sage


Reged: 10/26/12

Loc: De Soto County, MS
Re: Declining Quality of Premium Optical Glass [Re: M13 Observer]
      #5534689 - 11/23/12 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


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