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Equipment Discussions >> Refractors

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10gauge
sage


Reged: 10/31/10

Loc: Boston
Declining Quality of Premium Optical Glass
      #5528814 - 11/19/12 09:08 PM

There seems to be an alarming trend in securing premium optical glass for us refractorphiles. Summarizing from a few threads in the Yahoo TEC Group, Yuri has seen an increase in the rejection ratios of premium glass. It appears that the quality of CaF2 and FPL53 premium glass is not what it was 10 years ago. He is having to send lenses back to Ohara for visible striae in artificial star tests. In another thread he stated that he is not taking any new orders for the APO 160FL at this time. He feels that the quality of large lenses are in decline, even to the point of shifting production to reflectors if the situation does not improve. That would be a sad day. How do people feel about the future trends, philosophy, and quality of optical glass?...

http://tech.dir.groups.yahoo.com/group/tec-scopes/message/22839

I also noticed that the TEC 140 is now $5,700, up from $5,500. I ordered my TEC 140 a year ago, and I still haven't received it yet. Yuri said it would be done in 6 months as there were 50 people ahead of me. I am getting a little nervous... I am crossing my fingers, hoping I don't get the bottom batch of glass.


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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: 10gauge]
      #5528863 - 11/19/12 09:34 PM

Within this review of the Takahashi FS-78, about a third of the way down, there is a very interesting read about calcium fluorite crystal...

http://scopeviews.co.uk/TelescopeReviews.htm#_Takahashi_FS78

I read it just today, and it finally confirmed my suspicion as to why Takahashi practically abandoned calcium fluorite for its objectives.

Alan


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Danno2006
Pooh-Bah


Reged: 01/25/06

Loc: Ontario, Canada
Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5528920 - 11/19/12 09:59 PM

I owned a TEC140, bought a C14 and the TEC140 stayed in its case until I sold it. I moved away from a quality refractor and have not looked back. Given glass availability, LZOS may be the last manufacturer remaining making larger than 150mm premium quality, triplet refractors. I can't wait to see what kind of quality and aperature that Yuri can put into a compound mirror scope at the price point of a TEC180. Just noticed a 30" Starmaster dob at another site at the same price as the TEC180 tube - and the dob is mounted. The writing is on the wall, the king is dead, long live the new king.

Edited by Danno2006 (11/19/12 10:00 PM)


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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: Danno2006]
      #5528985 - 11/19/12 10:30 PM

"The writing is on the wall, the king is dead, long live the new king."

Might one suggest, analogously, the abandonment of a succinct novel in favour of comics.

Alan


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BillP
Postmaster
*****

Reged: 11/26/06

Loc: Vienna, VA
Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5529004 - 11/19/12 10:37 PM

Hopefully the Tak glass will stay high quality as I believe their lenses are made for them by Canon and Canon pours its own 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]
      #5529006 - 11/19/12 10:39 PM

Quote:

It appears that the quality of CaF2 and FPL53 premium glass is not what it was 10 years ago. He is having to send lenses back to Ohara for visible striae in artificial star tests. In another thread he stated that he is not taking any new orders for the APO 160FL at this time. He feels that the quality of large lenses are in decline, even to the point of shifting production to reflectors if the situation does not improve.






When the word got around that TEC was not producing larger apos I asked Yuri if fluorite quality was the reason, he said that the reason was the quality of mating elements and not the fluorite. Fluorite is available in larger sizes with the problem being the price which is astronomical.
FPL-53 has always been a problem with nominal 6” being its practical limit.

In another thread Yuri indicated that one of the reasons for not producing Maksutovs, again, is the glass quality needed for the meniscus. Using premium quality glass, which by the way is available, would increase the price of his 10” Mak to near 180FL price level.

Vahe


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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: BillP]
      #5529158 - 11/19/12 11:54 PM

Canon made the calcium fluorite lens of my FS-102.

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chboss
professor emeritus


Reged: 03/24/08

Loc: Zurich Switzerland
Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5529169 - 11/19/12 11:58 PM

Canon-Optron to be precise:
http://www.canon-optron.co.jp/english/

best regards
Chris


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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: chboss]
      #5529957 - 11/20/12 11:53 AM

When I purchased my apochromat in 2003, the A-P "Traveler" was out of the question given its limited availability and higher cost, and the TeleVue offerings with their "warm" views were never even considered. The FS-102 was on sale for $1899 at the time, and from Texas Nautical Repair...how could I resist? No matter, for while I might've strived towards purchasing the "Traveler", and in all probability, successfully, I had chanced upon this prior to making my decision...

http://www.scopereviews.com/aptak.html

I knew that it was special, but until recent light, I never knew just how special, and unique compared to the vast majority of all other apochromats.

And to think that so many owners of the FS series have sold and are presently selling off these true fluorite gems, for even less than what they paid when new, and for whatever reason, is nothing short of tragic.

Regards,

Alan


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5530078 - 11/20/12 12:48 PM

Fluorite optical glass is in reasonable supply and quality remains high. In fact, for large blanks this is the only reliable way to go unless you make your own ED glass as LZOS does.

I like the FS-series scopes, and have one now, and have had a couple of others. However, above 4" I don't find them to be particularly well color corrected visually. Even at 4" I can coax in-focus false color that is just detectable on very bright targets like Vega, Venus and Sirius. The 3" remains visually color free, but that's simply a function of the constant f/8 focal ratio for the line and the declining aperture.

That said, color correction isn't the do all to end all anyway. I find the figure quality on the FS scopes to be quite good, and the simple doublet design using extremely homogeneous fluorite scatters very little compared to harder glass doublets and triplets.

They're nice scopes. But even when they were being cleared out, they were relatively expensive given that they were totally "ala carte" and Tak accesories (clamshells, finders, etc.) are ridiculously expensive.

I also agree that folks selling them now are nuts. Hang on to them. The fluorite doublet is not coming back. As doublets go, these are about the ultimate iteration of the concept; the pinnacle of doublet refractor evolution.

Regards,

Jim


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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: jrbarnett]
      #5530199 - 11/20/12 01:36 PM

This morning I was mindful of the overlooked rear element within mine, as I understand it's well-matched to the fluorite, its high quality necessary even to that of the front element's performance, and in tandem to the doublet overall, so I've read, but I'm still unaware of its type.

Regards,

Alan


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Paul G
Post Laureate
*****

Reged: 05/08/03

Loc: Freedonia
Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5530245 - 11/20/12 01:58 PM

Quote:

Fluorite optical glass is in reasonable supply and quality remains high. In fact, for large blanks this is the only reliable way to go unless you make your own ED glass as LZOS does.

I like the FS-series scopes, and have one now, and have had a couple of others. However, above 4" I don't find them to be particularly well color corrected visually. Even at 4" I can coax in-focus false color that is just detectable on very bright targets like Vega, Venus and Sirius. The 3" remains visually color free, but that's simply a function of the constant f/8 focal ratio for the line and the declining aperture.

That said, color correction isn't the do all to end all anyway. I find the figure quality on the FS scopes to be quite good, and the simple doublet design using extremely homogeneous fluorite scatters very little compared to harder glass doublets and triplets.

They're nice scopes. But even when they were being cleared out, they were relatively expensive given that they were totally "ala carte" and Tak accesories (clamshells, finders, etc.) are ridiculously expensive.

I also agree that folks selling them now are nuts. Hang on to them. The fluorite doublet is not coming back. As doublets go, these are about the ultimate iteration of the concept; the pinnacle of doublet refractor evolution.

Regards,

Jim




I agree, they are very nice scopes. I had an FS128 and enjoyed using it. As you noted the false color is there if you know where to look, particularly if you have a color free scope to side by side with it. It also contributes to the "warm" tone the image has in the FS (blue is out of focus). If I had not been offered an AP 130 EDF I would not have sold the FS.


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RodgerHouTex
Pooh-Bah
*****

Reged: 06/02/09

Loc: Houston, Texas, USA
Re: Declining Quality of Premium Optical Glass new [Re: Paul G]
      #5530354 - 11/20/12 02:51 PM

I intend to be buried with my FS-152!

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TG
Pooh-Bah


Reged: 11/02/06

Loc: Latitude 47
Re: Declining Quality of Premium Optical Glass new [Re: 10gauge]
      #5530450 - 11/20/12 03:39 PM

Quote:

... He feels that the quality of large lenses are in decline, even to the point of shifting production to reflectors if the situation does not improve. That would be a sad day. How do people feel about the future trends, philosophy, and quality of optical glass?...





The real sad day for me was when I found out that TEC was no longer making their Maks. So you're saying there is hope yet!

Tanveer.


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Jarno
member


Reged: 05/22/05

Loc: Netherlands
Re: Declining Quality of Premium Optical Glass new [Re: jrbarnett]
      #5530628 - 11/20/12 05:00 PM

Quote:


I also agree that folks selling them now are nuts. Hang on to them. The fluorite doublet is not coming back.




A couple of years ago I bought a Vixen FL102 which uses the same Canon/Optron optics. If you ever see my scope for sale you'll know I'm either six feet under or own its Tak half-brother. 'Nuff said.


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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: RodgerHouTex]
      #5530658 - 11/20/12 05:23 PM

I second that!

Alan


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: TG]
      #5530683 - 11/20/12 05:36 PM

Quote:

Quote:

... He feels that the quality of large lenses are in decline, even to the point of shifting production to reflectors if the situation does not improve. That would be a sad day. How do people feel about the future trends, philosophy, and quality of optical glass?...





The real sad day for me was when I found out that TEC was no longer making their Maks. So you're saying there is hope yet!

Tanveer.




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. He was thinking about making shorter focal length reflectors with near focus refractive corrector type systems instead, or something to that effect. One never knows until it is actually produced though.


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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]
      #5530747 - 11/20/12 06:14 PM

Quote:

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.


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vahe
professor emeritus


Reged: 08/27/05

Loc: Houston, Texas
Re: Declining Quality of Premium Optical Glass new [Re: TG]
      #5530819 - 11/20/12 06:53 PM

Quote:

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





Check out post #19837 on tec-ug.

Vahe


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Declining Quality of Premium Optical Glass new [Re: vahe]
      #5531333 - 11/20/12 11:40 PM

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?

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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 new [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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MrGrytt
scholastic sledgehammer


Reged: 07/28/05

Loc: Upstate New York
Re: Declining Quality of Premium Optical Glass new [Re: M13 Observer]
      #5535515 - 11/23/12 01:27 PM

Quote:

Quote:

"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


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carlcat
sage
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Reged: 11/26/07

Loc: Northern California
Re: Declining Quality of Premium Optical Glass new [Re: MrGrytt]
      #5535605 - 11/23/12 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?

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ValeryD
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Reged: 11/26/05

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Re: Declining Quality of Premium Optical Glass new [Re: TG]
      #5536613 - 11/24/12 03:08 AM

Quote:


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.


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ed_turco
Pooh-Bah
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Reged: 08/29/09

Loc: Lincoln, RI
Re: Declining Quality of Premium Optical Glass new [Re: ValeryD]
      #5537132 - 11/24/12 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.


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ValeryD
Vendor (Aries)
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Reged: 11/26/05

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Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5539701 - 11/26/12 01:06 AM

Quote:

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

Alan




Absolutely nonsense!


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MrGrytt
scholastic sledgehammer


Reged: 07/28/05

Loc: Upstate New York
Re: Declining Quality of Premium Optical Glass new [Re: ValeryD]
      #5539882 - 11/26/12 07:21 AM

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

Harvey


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Declining Quality of Premium Optical Glass new [Re: MrGrytt]
      #5539968 - 11/26/12 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


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JohnH
Carpal Tunnel
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Reged: 10/04/05

Loc: Squamish BC Moved!!!!!
Re: Declining Quality of Premium Optical Glass new [Re: TG]
      #5540111 - 11/26/12 11:07 AM

Quote:

Quote:

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.


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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: MrGrytt]
      #5540552 - 11/26/12 03:46 PM

http://en.wikipedia.org/wiki/Takahashi_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.com/product.aspx?pid=138-7123

...?

Alan


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MrGrytt
scholastic sledgehammer


Reged: 07/28/05

Loc: Upstate New York
Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5541136 - 11/26/12 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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Sky Muse
sage


Reged: 10/26/12

Loc: De Soto County, MS
Re: Declining Quality of Premium Optical Glass new [Re: MrGrytt]
      #5541154 - 11/26/12 10:07 PM

But we have this...

"...for larger telescopes."

...not telescopes, refractors or otherwise, in general.

...odd.

Alan


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Declining Quality of Premium Optical Glass new [Re: Sky Muse]
      #5541222 - 11/26/12 10:45 PM

Quote:

But we have this...

"...for larger telescopes."

...not telescopes, refractors or otherwise, in general.

...odd.

Alan




This is from Wiki, and it is from a stub. It is not confirmed, nor is it a quote from Takahashi. It has not been vetted. It is quite frankly a mis-statement. Just because you read it does NOT mean it is true.


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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]
      #5541318 - 11/26/12 11:32 PM

However, I seriously doubt that it was stubbed just for kicks, and insofar as it being a "mis-statement", who really knows?

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ckwastro
Pooh-Bah


Reged: 11/23/05

Loc: Tempe, AZ
Re: Declining Quality of Premium Optical Glass new [Re: TG]
      #5542564 - 11/27/12 06:07 PM

Quote:

The real sad day for me was when I found out that TEC was no longer making their Maks.




A friend of mine had the 10" f/20 for a while, and it was a work of art. I was disappointed as well to find out Yuri stopped making the Maks.


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plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: Declining Quality of Premium Optical Glass new [Re: ckwastro]
      #5542662 - 11/27/12 07:16 PM

If I'm not mistaken BK7 can be used for lenses and for mirrors but I would expect that the specifications and prices for premium optical quality would depend on the application.

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