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mikey cee
Postmaster
Reged: 01/18/07
Loc: bellevue ne.
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Re: Nobody is making a 6" doublet ED scope,
[Re: skybsd]
#5151925 - 04/01/12 03:37 PM
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Yadda yadda yadda..... I love my new Istar 10" F/11 R30. It costs big bucks but then again it isn't a 6" or 8" either. Mars has such a minute thin red lavender residual color that a forthcoming Raycorr 6 definitely would give me an apo or so dang close as to make it a no brainer for me! The lavender residual on Jupiter too is so small that a Raycorr 6 shouldn't have much to overcome there either. I can't wait!  Mike
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APM M.Ludes
Vendor (APM Telescopes)
Reged: 05/01/03
Loc: Germany
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Re: Nobody is making a 6" doublet ED scope,
[Re: vahe]
#5151976 - 04/01/12 04:08 PM
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Vahe
you are very right, but thats a high end doublet fluorite, now a cheap ED what is under discussion here.
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APM M.Ludes
Vendor (APM Telescopes)
Reged: 05/01/03
Loc: Germany
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Re: Nobody is making a 6" doublet ED scope,
[Re: APM M.Ludes]
#5151989 - 04/01/12 04:18 PM
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so my friends, the first step is done, the choosen Glas for the design of the cheap ED Douplet is Chinese FK 61 ( same as Ohara FPL51).
The choosen manufacturer told me if we want good prices, we must do a production run of 250 pc , if we go with much less, glas cost much more.
this means 250 pc scopes , lets gues $ 2,000 each would be 500,000.00 $ , if each cost $ 3,000, then we talk about 750,000.00 $ pre-investment
Thats a lot of money for investment . So we have to buy at least the 250 pc glas blank sets to start and discuss with the manufactur batches per production run, otherwise I have sell my nice car :-(
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ValeryD
Vendor (Aries)
Reged: 11/26/05
Loc: Kherson, Ukraine.
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Re: Nobody is making a 6" doublet ED scope,
[Re: APM M.Ludes]
#5152035 - 04/01/12 04:50 PM
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so my friends, the first step is done, the choosen Glas for the design of the cheap ED Douplet is Chinese FK 61 ( same as Ohara FPL51).
The choosen manufacturer told me if we want good prices, we must do a production run of 250 pc , if we go with much less, glas cost much more.
this means 250 pc scopes , lets gues $ 2,000 each would be 500,000.00 $ , if each cost $ 3,000, then we talk about 750,000.00 $ pre-investment
Thats a lot of money for investment . So we have to buy at least the 250 pc glas blank sets to start and discuss with the manufactur batches per production run, otherwise I have sell my nice car :-(
Markus,
H-FK61 is normally available in strips 125mm wide. How can you obtain 158mm round blanks? Also all these 158mm blanks must be of highest homogeneity and annealed not as strips, but as round flat blanks.
All H-FK61 glass scopes are limited to 110mm objectives only. All larger have FCD-1 Hoya or FPL53 glasses in them.
You'd better use your car for a pleasure, than take a risk in a 6" H-FK61 adventure. I tried to get such sizes H-FK61 several years ago with exactly the same (as discussed here) idea in mind. But I gave up because of a strip wide limitations. Even if you do have 160mm strip wide, you can't drill out a round disk of, say 150mm and make a lens for an objective, because the lens will have an astigmatism even if it's surfaces are perfectly made.
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skyjim
Carpal Tunnel
Reged: 01/13/07
Loc: Long Island, NY
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Re: Nobody is making a 6" doublet ED scope,
[Re: APM M.Ludes]
#5152107 - 04/01/12 05:51 PM
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Markus, please dont sell your nice car, I would feel terible to see you hitch hiking to work in Germany, lol. I think just maybe will see a 6" ED doublet outa china within the next year, it will be either JOC or Kuming, and I would be totally surprised if Synta does it but who knows. When I look at how many folks have 120mmED doublets and they are very pleased with these scope and now Synta has there better triplets in production just maybe they might bring out a doublet for the visual folks, not everyone does ap. I think I will look at the Istar company for now, it might not be an ED but a better corrected achro, as far as Valeries H bomb well I would rather not waite that long cause he seems to be talking about another few years before that scope reaches the marketplace. Regarding the coments on dreaming well I just thought why not stir up the pot a little, belive me I live in the real world and have a very good idea on was these lenses may cost, I also belive that if it was for the camera market, hell you would see things happen allot faster, this hobby is soo small that advancments take time.
Jim
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APM M.Ludes
Vendor (APM Telescopes)
Reged: 05/01/03
Loc: Germany
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Re: Nobody is making a 6" doublet ED scope,
[Re: ValeryD]
#5152111 - 04/01/12 05:54 PM
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Valery
several years ago many things has not been available !!!
I really don't care whats available or not, I care on my supplier , the guarantee I have from him, how much I can trust him and on the return policy in case of a problem, that is all what counts !!
See what Synta did many years ago and what they do today, many things changed very much in years.
The risk is not the quality, we will controle it and return bad things at manufacturers expenses, thats the deal
the risk is that we do it and nobody buys it :-)
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wh48gs
Pooh-Bah
Reged: 03/02/07
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Re: Nobody is making a 6" doublet ED scope,
[Re: APM M.Ludes]
#5152364 - 04/01/12 09:05 PM
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We need you to confirm the glass type,because as we know,the only good combination for such F ratio is FPL-51 + NBM-51,but the NBM-51 is not cheap,the cost is even as expensive as FPL-53 type.
Ohara NBM-51 is the equivalent of hard-to-find NASA short-flint (Schott KZFS1), and isn't even best match for the FPL51; it would have no better than 1/4 to 1/5 of the seconday spectrum of a comparable achromat. The problem with FPL51 is that it have a few good pairing glasses for a true apo; one is Schott SK55, but due to the relatively small dispersive powers between the two it can only work for f/12 or slower objective at 6" aperture. Lanthanum glass (Schott LAK31) is better in that respect, nearly as good at f/10, but it is not normally used, being 17 times the BK7 price. The best match seems to be Schott's KZFSN2 (no Ohara equivalent), offering similar performance almost down at f/8, at 10 times the BK7 price.
Vla
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robboski2004
member
Reged: 01/14/08
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Re: Nobody is making a 6" doublet ED scope,
[Re: wh48gs]
#5152462 - 04/01/12 10:46 PM
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The best match seems to be Schott's KZFSN2 (no Ohara equivalent), offering similar performance almost down at f/8, at 10 times the BK7 price.
Vla
Vla, i'm not sure where the 10x comes from !
20x the BK7 strip price would be minimum !
getting a large enough piece might present a problem aswell,
in fact does this glass really exist 
regards.
Ian.
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wh48gs
Pooh-Bah
Reged: 03/02/07
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Re: Nobody is making a 6" doublet ED scope,
[Re: robboski2004]
#5153526 - 04/02/12 04:34 PM
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Ian,
That is what OSLO glass catalog quotes (9.7x). I see that GLD lists BK7 at $9.40 and KZFSN2 at $141, which is more like 15x. It does vary with the supplier (and with the BK7 price).
Vla
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ValeryD
Vendor (Aries)
Reged: 11/26/05
Loc: Kherson, Ukraine.
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Re: Nobody is making a 6" doublet ED scope,
[Re: wh48gs]
#5153660 - 04/02/12 06:19 PM
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Ian,
That is what OSLO glass catalog quotes (9.7x). I see that GLD lists BK7 at $9.40 and KZFSN2 at $141, which is more like 15x. It does vary with the supplier (and with the BK7 price).
Vla
It is really quoted at 20x to BK7 rate!
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ValeryD
Vendor (Aries)
Reged: 11/26/05
Loc: Kherson, Ukraine.
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Re: Nobody is making a 6" doublet ED scope,
[Re: APM M.Ludes]
#5153671 - 04/02/12 06:24 PM
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Valery
several years ago many things has not been available !!!
I really don't care whats available or not, I care on my supplier , the guarantee I have from him, how much I can trust him and on the return policy in case of a problem, that is all what counts !!
See what Synta did many years ago and what they do today, many things changed very much in years.
The risk is not the quality, we will controle it and return bad things at manufacturers expenses, thats the deal
the risk is that we do it and nobody buys it :-)
You do not understand what did I mean. I mean that CDGM glass plant has a limit of the strips wide for H-FK61 glass.
This limit is 127mm. You can't go even with 5" lenses with H-FK61.
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wh48gs
Pooh-Bah
Reged: 03/02/07
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Re: Nobody is making a 6" doublet ED scope,
[Re: ValeryD]
#5153707 - 04/02/12 06:54 PM Attachment (42 downloads)
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It is really, relly quoted as shown 
Not all OSLO versions have necessariy identical price quotes, and not all BK7s are created equal. One knows it when s/he asks supplier. Any indirect quotes are unavoidably approximate.
Vla
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alancygnusx2
professor emeritus
Reged: 11/25/08
Loc: CA
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Re: Nobody is making a 6" doublet ED scope,
[Re: ValeryD]
#5153801 - 04/02/12 08:11 PM
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I have never understood why the machines producing the glass strips limit the width so much. If they pour the glass onto a wider strip does it cause problems by reducing the homogeneity of the glass?
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robboski2004
member
Reged: 01/14/08
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Re: Nobody is making a 6" doublet ED scope,
[Re: ValeryD]
#5153966 - 04/02/12 10:51 PM
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Quote:
Quote:
Ian,
That is what OSLO glass catalog quotes (9.7x). I see that GLD lists BK7 at $9.40 and KZFSN2 at $141, which is more like 15x. It does vary with the supplier (and with the BK7 price).
Vla
It is really quoted at 20x to BK7 rate!
Valery,
I have approached an optical glass house in Germany.
I will advise the cost of all the Kz types by Euro/Kg.
N-Kzfs4 is approx 380/kg ...N-Kzfs11 is over 1000/kg
i'm guessing N-Kzfs2 will split the difference ?
also very few sources ever seem to have much anyway !
i'll advise.
Ian.
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ValeryD
Vendor (Aries)
Reged: 11/26/05
Loc: Kherson, Ukraine.
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Re: Nobody is making a 6" doublet ED scope,
[Re: robboski2004]
#5154017 - 04/02/12 11:53 PM
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Quote:
Quote:
Quote:
Ian,
That is what OSLO glass catalog quotes (9.7x). I see that GLD lists BK7 at $9.40 and KZFSN2 at $141, which is more like 15x. It does vary with the supplier (and with the BK7 price).
Vla
It is really quoted at 20x to BK7 rate!
Valery,
I have approached an optical glass house in Germany.
I will advise the cost of all the Kz types by Euro/Kg.
N-Kzfs4 is approx 380/kg ...N-Kzfs11 is over 1000/kg
i'm guessing N-Kzfs2 will split the difference ?
also very few sources ever seem to have much anyway !
i'll advise.
Ian.
And the process will be non stop.
Absolutely perfect coating. Whe can warranty it. Ok, for a year. And then. KzF
It is really cheaper to make triplets, but they are not cheap either. So, we need to accept less than perfect color correction in FPL51 class ED and slower F/D in doublets or higher cost in triplet at F/8.
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Rich
member
Reged: 01/21/06
Loc: Seattle
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Re: Nobody is making a 6" doublet ED scope,
[Re: ValeryD]
#5154115 - 04/03/12 01:54 AM
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I've always wondered about this topic, not only for the price difference between triplet apo and doublet ED, but because of the lighter weight and faster cool down. I thought I recalled Vic Maris discussing this... and found this over at the Stellarvue group from 2008:
"When you upsize to 110, 120 or 130mm, the f-7 ED doublet has completely unacceptable false color in my opinion. Conventional methods of controlling this color which include using an expensive Fluorite or a Lanthanum Secondary element is costly. This negates the goal of making something larger and less expensive. I have not been satisfied with the 120mm f-7 or f-8 ed doublet even when made with FPL-53. For me, making a color free apo triplet is the better solution. It focuses light more precisely and is free of false color. Everyone wants a deal but I find it interesting how the laws of physics, cost and manufacturing limitations kick in whenever you design and build a product at a certain price level."
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APM M.Ludes
Vendor (APM Telescopes)
Reged: 05/01/03
Loc: Germany
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Re: Nobody is making a 6" doublet ED scope,
[Re: Rich]
#5154202 - 04/03/12 06:41 AM
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Hi Rich
the point is a 120 mm triplet cost $ 4,000 and up a 120 mm FPL 53 doublet cost around $ 2,000, half the price
For CCD guys the diffrence is big, for visual guys very very little
all depends what you want todo with the scope. Vic has proberly the CCD imagers more in mind
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Vondragonnoggin
Post Laureate
Reged: 02/21/10
Loc: Southern CA, USA
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Re: Nobody is making a 6" doublet ED scope,
[Re: Rich]
#5154204 - 04/03/12 06:42 AM
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I keep wondering why the last 5 or 6 posts are talking about mating elements that are expensive to try and make the most color correction in a doublet, when the thread was talking about an ED doublet not trying to be the most color corrected, but rather a middle ground scope in cost and color correction. Somewhere between apo and achro and not be longer than about F/8 at most.
It seems, again, that the idea of not trying to achieve the most color correction possible, is rather a difficult one to fathom. If we are talking about 1/4 the false color of an achromat of the same focal length, that is a huge improvement. That's a 75% reduction in chromatic aberration. That would have surpassed my expectations of a scope sold with a description of semi-apo.
Or maybe I am completely misunderstanding the posts......
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skyjim
Carpal Tunnel
Reged: 01/13/07
Loc: Long Island, NY
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Re: Nobody is making a 6" doublet ED scope,
[Re: Vondragonnoggin]
#5154280 - 04/03/12 08:20 AM
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Your right on the money Eric, this post is changing into a optical glass post about color free, triplets being better so I do feel its being hijacked and to top it off I got someone telling me I'm a dreamer, lol....
Jim
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Sean Puett
Carpal Tunnel
Reged: 09/06/10
Loc: always cloudy, washington
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Re: Nobody is making a 6" doublet ED scope,
[Re: Vondragonnoggin]
#5154286 - 04/03/12 08:25 AM
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Markus has the idea down. That is what matters. If you could get it close to my genesis sdf then i think all the visual guys would be ecstatic. The only false color i have seen is on Venus and you have to take it inside or outside of focus to see it. This is a 4"f5.4 and a nearly 20 year old scope. I would think that you could get color correction to "good enough" at f8 or so with decent glass. Maybe Venus still shows color but, how often are you looking at Venus? When using the scope as intended and not looking specifically for flaws, you will enjoy the scope more. Since joining this site i have been trained to look for flaws in my equipment and i find them. It is a bit of insanity though. I buy something new then do everything i can to make flaws obvious.
If i hadn't joined this or another site, i would have said my genesis sdf has no false color and been nearly correct but, now i have to mention it and it sounds far worse than what i see at the eyepiece. For some reason, CA is on the top of the list when refractors are evaluated.
Anyway, you guys are on track to get what you want. It may be more money than some of the people have stated they would pay but, it is possible to get what you are seeking. I have seen enough of these types of threads that i believe they will sell. It just may take some time.
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