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Equipment Discussions >> Refractors

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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: TEC 200 new [Re: Daniel Mounsey]
      #4249152 - 12/14/10 08:46 PM

I am looking into making a large refractor (8 to 10 inch) by grinding my own objective lens and am considering doing it with ED glass. I am finding out that a lot of the ED glass material is going out of production and the stock sizes are in smaller widths seeming to be more in the 180 mm and 160 mm sizes. You can have some melted for larger sizes but you would have to be a millionaire to afford that.I have not even checked on the prices for the stock available yet but I bet that it will make me yowl and go for the usual flint design !!!

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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: TEC 200 new [Re: jimegger]
      #4249793 - 12/15/10 07:43 AM

Good luck on your venture. D & G attempted doublet ED refractors and they threw in the towel on it. Too hard to make, and they are set-up for production! They now stick to achro's.

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Jeff B
Carpal Tunnel
*****

Reged: 12/30/06

Re: TEC 200 new [Re: t.r.]
      #4249845 - 12/15/10 08:26 AM

I once asked Barry if I gave him the ED glass, would he do the lens? There was a brief chuckle followed by "No".

Jeff


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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: TEC 200 new [Re: Jeff B]
      #4251583 - 12/16/10 12:34 AM

Not only is it getting harder to find the bigger size ED glasses for an objective in the 8 inch size range , they are darned expensive and anyone using them in lens production really needs to be careful in handling it plus they are finicky in you really need to be on your game in holding tolerances. Someone set up for production such as Barry would be taking a chance in trying something out of the norm. In some respects doing a one time job on specialty glass would be better for someone not set up for production. I am no expert at optical design although I did turn out a really nice 6 inch achromatic doublet. I have seen that the economy situation is making the different manufacturers cut back on production and sizes of materials not heavily used are taking a back seat. It always seems to go that way when things get tough. The Tec scopes are at the cutting edge of optical design and would be among the first to feel the pinch. I hope Yuri keeps it going because he sure has a great product line. I'd like to see even larger ED scopes come out in the future. Wouldn't a 10 inch be nice !!

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Mike Clemens
Frozen to Eyepiece
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Reged: 11/26/05

Loc: Alaska, USA
Re: TEC 200 new [Re: jimegger]
      #4251645 - 12/16/10 02:44 AM

I always hear about homogeneity problems, stria, and other things which make buying thousands in glass blanks sound terrifying. Coating and THEN finding out about probs, etc.

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jimegger
Pooh-Bah
*****

Reged: 12/22/05

Loc: Palmer,Alaska
Re: TEC 200 new [Re: Mike Clemens]
      #4252460 - 12/16/10 02:43 PM

Quote:

I always hear about homogeneity problems, stria, and other things which make buying thousands in glass blanks sound terrifying. Coating and THEN finding out about probs, etc.




You got that right Mike !!! We little guys can ill afford to have that expense for experimentation purposes. Right now no one is huge when it comes to optical design and implementation especially in this economy. When the money is rolling in it is best to take chances otherwise stick to the tried and true and let someone else take the risks. ( I think I just talked myself into a classical 8 inch doublet design !)


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Mike Clemens
Frozen to Eyepiece
*****

Reged: 11/26/05

Loc: Alaska, USA
Re: TEC 200 new [Re: jimegger]
      #4252537 - 12/16/10 03:25 PM

I think even the big guys don't like to take those chances. I think thats why you cannot order an 8" APO from USA right now.

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Muffin Research
Carpal Tunnel


Reged: 09/28/07

Loc: Belgium
Re: TEC 200 new [Re: Mike Clemens]
      #4252570 - 12/16/10 03:41 PM

so no love for these guys here?
Big lens

Although I can't get my mind around the money for these things.. I mean for that amount I can buy twice the size quality reflector and a nice 4/5" widefield Apo and be done with it and still have money left.
And scopes like this need observatories and heavy duty expensive mounts.

Still sure envy those who can put this in their backyard (and live in great skies)
If you see these sticking out of a Manhattan high rise building you probably think 'schmuck'


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skybsd
Post Laureate
*****

Reged: 02/01/08

Re: TEC 200 new [Re: Muffin Research]
      #4252593 - 12/16/10 03:53 PM

Quote:

so no love for these guys here?
Big lens




Pretty sure "love" is not a problem - indeed, I'm pretty sure there's lots of "love".., . Its the "money" that's the problem - or lack thereof..,

Regards,

skybsd


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Mike Clemens
Frozen to Eyepiece
*****

Reged: 11/26/05

Loc: Alaska, USA
Re: TEC 200 new [Re: skybsd]
      #4252598 - 12/16/10 03:56 PM

It's awesome until something goes wrong and you need it serviced.

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skybsd
Post Laureate
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Reged: 02/01/08

Re: TEC 200 new [Re: Mike Clemens]
      #4252637 - 12/16/10 04:12 PM

Hi Mike,
Just curious.., What would typically crop up that fits the "something goes wrong" scenario in the case of such a scope (lens)?

Regards,

skybsd


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Mirzam
Post Laureate
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Reged: 04/01/08

Loc: Lovettsville, VA
Re: TEC 200 new [Re: skybsd]
      #4252662 - 12/16/10 04:27 PM

Well, I can tell you one problem. I have a 180mm TMB with a poorly designed lens cell that does not hold the rear element with proper centering. My reason for keeping it is to rework the cell myself one of these days to try and revive the thing. Unfortunately, when TMB passed on, APM did not take up the cause or support the scopes that they had manufactured on TMB's behalf. Long term support is one of the great benefits of dealing with TEC, although I have never heard of their scopes requiring any support. (And I have owned two).

JimC


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skybsd
Post Laureate
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Reged: 02/01/08

Re: TEC 200 new [Re: Mirzam]
      #4252679 - 12/16/10 04:34 PM

Hello Jim,
Wow! Sounds like a right mess there.

I'll ask for the simple reason that I do not know. How long has TEC been producing and selling scopes compared to TMB - or various manifestations thereof?

Regards,

skybsd


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Mirzam
Post Laureate
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Reged: 04/01/08

Loc: Lovettsville, VA
Re: TEC 200 new [Re: skybsd]
      #4252794 - 12/16/10 05:20 PM

I don't know the history of TEC in any detail, but their website gives a good synopsis. They certainly have been going strong with the TEC 140s since the early 2000's. They made a small number of excellent maksutovs in the early years as well.

Thomas M. Back designed and assembled telescopes using lenses sourced from Europe until his death in (I think) 2006 or 2007. Newer TMB's are Back designs that are manufactured in China. The newer TMB branded scopes are supported by the companies that sell them, including Astronomics. (My problem scope is one of the older APM-sourced models made around ~10 years ago).

JimC


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timwetherell
sage
*****

Reged: 09/03/10

Loc: A Land Down Under
Re: TEC 200 new [Re: jimegger]
      #4252798 - 12/16/10 05:22 PM

Quote:

Wouldn't a 10 inch be nice !!




It sure would be a beautiful thing to behold! Though I suspect that once you start getting into huge apertures the "refractor advantage" begins to wear off. And of course the $$$ become crazy. I think that APM do make scopes in this range but I'd imagine that they're specials to order rather than stock items.

Did anyone see that 14 or 15" apo lens that was being sold off on Astromart a year or so back? I think it was ordered then not collected or something

all the best

Tim


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skybsd
Post Laureate
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Reged: 02/01/08

Re: TEC 200 new [Re: Mirzam]
      #4252813 - 12/16/10 05:29 PM

Hello Jim,
Thanks for that..,

Did you ever actually get an explanation or statement from them as to why support was withdrawn (or refused?). Whilst this is not unheard of (lots of instances of similar across many industries), this sort of change is normally accompanied by some appropriate communication or statement of intent - you see.

Regards,

skybsd


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Mike Clemens
Frozen to Eyepiece
*****

Reged: 11/26/05

Loc: Alaska, USA
Re: TEC 200 new [Re: timwetherell]
      #4252816 - 12/16/10 05:30 PM

I might feel different if LZOS serviced the lenses once sold. Even though it would involve shipping to Russia and back. When something approaches the price of a new car, I want an awesome plan for service if required.

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Mirzam
Post Laureate
*****

Reged: 04/01/08

Loc: Lovettsville, VA
Re: TEC 200 new [Re: skybsd]
      #4252869 - 12/16/10 06:05 PM

I contacted a company in Florida, the name of which was given to me by Teton Telescopes (who had nothing to do with my used scope other than being a US retailer for APM). I don't recall the name of the Florida company, but my understanding was that they did service work for APM products. Anyway they discussed the problem with me but did not agree to try and fix the problem. It's not like I was looking for warranty service--I was willing to pay them! However, the problem may also be unfixable, in which case they took the safe option.

The moral of this tale is that purchasing expensive used equipment always has some risk. If Thomas Back were still around my experience might have been different. Let's leave it at that.

JimC


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vahe
scholastic sledgehammer


Reged: 08/27/05

Loc: Houston, Texas
Re: TEC 200 [Re: jimegger]
      #4253287 - 12/16/10 09:11 PM

Quote:

Wouldn't a 10 inch be nice !!




Once you go above 8” cooling issues become fairly serious, a 10” air spaced a triplet apo is only useable to its full potential if it is located in tropical climate with very little temperature drops day/night.

Vahe


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john 127
super member


Reged: 01/17/08

Loc: Napa, CA
Re: TEC 200 new [Re: Daniel Mounsey]
      #4253732 - 12/17/10 01:12 AM

Hi Daniel

Yes, it was originally John Curry's. I agree with you on the F9 ED over the F8 Fluorite. The gentleman I bought the scope from had experience with both and he said he didn't notice much of a difference and the fluorite is a lot more expensive. I have also heard that #005 tests quite well. I really didn't know anything about scopes in this size but figured I'd take a gamble. Like your review of this scope says the views of the planets are absolutely jaw dropping! We should have the observatory built by Spring so until then it mostly stays in the case. It helps me work on my patience!


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