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Fluorite vs ED

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#26 Eddgie

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Posted 06 August 2015 - 04:53 PM

So first it was the color correction..

Then it was the transmission.

 

And now it is the scatter.

 

And the cooling.

 

Ok, soon it will be the seeing too.. LOL>

 

Geesh.   I thought refractors were supposed to perfect.  People on the forums say that all the time.  And now I find out that unless you buy a Fluorite, you really might as well have bought an achormat.. LOL. 

 

And now I am finding out that unless it is fluorite, it is really inferior.

 

That must make a lot of people feel bad.. LOL..

 

He, I am only kidding here, but seriously???????  Do people really think that Fluorite is that much better?  

 

Its no wonder that I don't hang around the refractor forum so much. Quick to ignore issues with refracting design and deplore anything else,   and then go into hyper nit-pick mode over a difference so infinitesimal that it can be dismissed and should be dismissed far what it is which is urban legend and marketing.



#27 Sky Muse

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Posted 06 August 2015 - 04:55 PM

From what I have read and understand, the reason for choosing fluorite is today not so much the color correction that can be achieved, but the much lower scatter. Fluorite can be exceptionally pure and will basically scatter no light at all. A famous test is to shine a green laser through the objective and the beam is invisible where it passes through the fluorite, while it is easily visible where it passes through normal glass.

 

 

Clear skies!
Thomas, Denmark

 

The light-scatter aspect was precisely the reason why I chose an FS-102 over Tele Vue's TV102, and back in the early 2000s.



#28 Eddgie

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Posted 06 August 2015 - 05:07 PM

Lots of ammunition here for the reflector forum. LOL...



#29 BillP

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Posted 06 August 2015 - 06:52 PM

 

From what I have read and understand, the reason for choosing fluorite is today not so much the color correction that can be achieved, but the much lower scatter. Fluorite can be exceptionally pure and will basically scatter no light at all. A famous test is to shine a green laser through the objective and the beam is invisible where it passes through the fluorite, while it is easily visible where it passes through normal glass.

 

 

Clear skies!
Thomas, Denmark

 

The light-scatter aspect was precisely the reason why I chose an FS-102 over Tele Vue's TV102, and back in the early 2000s.

 

 

This is what I read most often from folks.  Not paper exercises with color correction, but the visual of the image has a better aesthetic quality.



#30 BillP

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Posted 06 August 2015 - 06:59 PM

Lots of ammunition here for the reflector forum. LOL...

 

My preference is that there would be no separate forums.  At least not to the level they go here.  Should just be one forum for equipment.  Having Refractor and Reflector and SCT and all just encourages division, and comments like this.  We should not be encouraging division within our hobby.  All of us are typically interested in everything equipment-wise anyway.  If people want to pursue perfection, there is nothing wrong with that nor should it be suggested that there is.  And if people want to observe with a more casual attitude and don't care if the system strehl is 80, then that is fine also.  It should only be about what a particular person wants, then discussing how they can get there.  There is no right or wrong, and should be no gathering of ammunition to use against our fellow hobbyists. If folks want division...then they can re-energize the forums on the "other site" as it was what they were famous for, and what ultimately left them like the cricket land they currently are.


Edited by BillP, 06 August 2015 - 07:13 PM.


#31 Niklo

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Posted 06 August 2015 - 07:41 PM

Lots of ammunition here for the reflector forum. LOL...

Hello Eddgie,

you know more about optic design of refractors than me. I wrote that I'm unsure about the facts and so it's good when you correct me but I don't like the way you write here like talking down to us.

Clear sky,

  Roland



#32 PowellAstro

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Posted 06 August 2015 - 07:58 PM

This link may interest some of you. Written by Neil English about fluorite.

http://neilenglish.n...jective-design/

#33 Bomber Bob

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Posted 06 August 2015 - 08:37 PM

Bill, I agree with your sentiment, but putting all scope designs in one forum would make scrolling through threads tedious - especially on a tablet.  So for purely selfish reasons, I'm against it.  I'm also against these "my scope is better than your scope because -- science!" posts & threads.  This is a HOBBY!  I don't obsess about tech specs, I'm in it for the views.



#34 Sky Muse

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Posted 06 August 2015 - 09:05 PM

This link may interest some of you. Written by Neil English about fluorite.

http://neilenglish.n...jective-design/

 

Alas, such may very well be, however 'tis the price to pay for the privilege of observing the heavens, unobstructedly, without a cataract, and through what essentially amounts to a gemstone, rather than more common optical glasses and aluminised non-optical glasses.



#35 BillP

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Posted 06 August 2015 - 09:55 PM

Takahashi does not seem to have any issue working with Fluorite, multicoating it, placing it in scope and not having any longevity problems, and all while abiding by the very strict Japanese eco-friendly laws.  So IMO, not a thing wrong with Fluorite in an objective, and as many point out, provides a special character to the view.  So if you have the skill and expertise to work with this, then by all means do so.


Edited by BillP, 06 August 2015 - 09:56 PM.


#36 Astrojensen

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Posted 07 August 2015 - 02:03 AM

Let's face it, refractors are interesting to talk about, because their design, compared to the mirrors of a reflector*, can be almost infinitely variable. Designing and making refractors is almost more an art, than it is engineering. It's like cars and car engines, with different displacements, carburettors, flywheel weights, compression, etc. There is engineering in it, but it's ultimately down to a large amount of feeling and careful judgement by experts of where the balance between all the different factors should lie. 

 

Also, refractors, while often theoretically inferior to reflectors, often perform wonderfully well in practice. Reflectors, often theoretically superior, in practice nonetheless struggles to keep up. They nearly always do inch for inch and very often even when given a respectable aperture advantage. This naturally sparks debate and is the sort of thing that creates very strong brand loyalty, or in this case, design loyalty, towards the refractor.  

 

*) There are of course a huge number of reflector designs, but many of them are obscure and people tend to think of a newtonian or a cassegrain, when they hear the word "reflector". 

 

 

Clear skies!
Thomas, Denmark



#37 Paul G

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Posted 07 August 2015 - 05:27 AM

Takahashi does not seem to have any issue working with Fluorite, multicoating it, placing it in scope and not having any longevity problems, and all while abiding by the very strict Japanese eco-friendly laws.  So IMO, not a thing wrong with Fluorite in an objective, and as many point out, provides a special character to the view.  So if you have the skill and expertise to work with this, then by all means do so.

 

Tak just assembles, Canon does the manufacturing which is where any eco concerns would lie, and Canon cranks out fluorite elements by the millions for industry and Canon L lenses. The eco issue was raised by a Tak European dealer when they were questioned about abandoning the "fluorite advantage." And it's still made in Germany where eco laws are much tougher than in Japan.


Edited by Paul G, 07 August 2015 - 05:28 AM.


#38 Traveler

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Posted 07 August 2015 - 06:00 AM

In my FS60-CB, the starpoints looks very small. Smaller than in any ED refractor i have seen through.  Maybe it has in someway to do with the fluorite element in the scope or maybe some other aspects of my scope and/or the others scopes.

 

Do i really care if its because of the fluorite element? No, i just enjoying the pinpoint sharp views of this little fellow very very much! :D



#39 BillP

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Posted 07 August 2015 - 07:59 AM

 

Takahashi does not seem to have any issue working with Fluorite, multicoating it, placing it in scope and not having any longevity problems, and all while abiding by the very strict Japanese eco-friendly laws.  So IMO, not a thing wrong with Fluorite in an objective, and as many point out, provides a special character to the view.  So if you have the skill and expertise to work with this, then by all means do so.

 

Tak just assembles, Canon does the manufacturing which is where any eco concerns would lie, and Canon cranks out fluorite elements by the millions for industry and Canon L lenses. The eco issue was raised by a Tak European dealer when they were questioned about abandoning the "fluorite advantage." And it's still made in Germany where eco laws are much tougher than in Japan.

 

 

I take the TV stance on this...if Tak is commissioning the work to their design spec, then it is theirs.  Tak and Canon have a "relationship" and for all practical purposes in this realm are like one.  But anyway, are you saying that all the Fluorite Tak uses is produced in Germany?  And I still see no abandonment of their take on the Fluorite Advantage as it is still actively stated by them in the literature I see.  So what gives?



#40 Paul G

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Posted 07 August 2015 - 09:14 AM

 

 

Takahashi does not seem to have any issue working with Fluorite, multicoating it, placing it in scope and not having any longevity problems, and all while abiding by the very strict Japanese eco-friendly laws.  So IMO, not a thing wrong with Fluorite in an objective, and as many point out, provides a special character to the view.  So if you have the skill and expertise to work with this, then by all means do so.

 

Tak just assembles, Canon does the manufacturing which is where any eco concerns would lie, and Canon cranks out fluorite elements by the millions for industry and Canon L lenses. The eco issue was raised by a Tak European dealer when they were questioned about abandoning the "fluorite advantage." And it's still made in Germany where eco laws are much tougher than in Japan.

 

 

I take the TV stance on this...if Tak is commissioning the work to their design spec, then it is theirs.  Tak and Canon have a "relationship" and for all practical purposes in this realm are like one.  But anyway, are you saying that all the Fluorite Tak uses is produced in Germany?  And I still see no abandonment of their take on the Fluorite Advantage as it is still actively stated by them in the literature I see.  So what gives?

 

1) They may have a "relationship" but the manufacturing, grinding, polishing, and coating are done elsewhere, they don't "work with fluorite" in any environmentally meaningful way so any environmental concerns are moot.

 

2) I never said Tak gets their fluorite from Germany, please re-read my post. Just pointing out that the eco excuse for switching to FPL53 floated by Tak dealers doesn't seem to have any basis in fact. But after beating the fluorite-is-better-than-FPL53 drum for so many years only to have Tak switch to FPL53 they had to have something to appease the faithful.

 

3) There's what they say and there's what they do. At one time all of Tak's flagship refractors had a fluorite element, now their flagship refractors with the best color correction in Tak history are FPL53 scopes. And Tak dealers have a history of over the top claims on their web sites; for years all the Tak dealers posted a claim that, to be true, would have required competitors' high quality equal aperture scopes to have a light throughput of about 60%, absolute nonsense.



#41 Niklo

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Posted 07 August 2015 - 09:55 AM

Let's face it, refractors are interesting to talk about, because their design, compared to the mirrors of a reflector*, can be almost infinitely variable. Designing and making refractors is almost more an art, than it is engineering. It's like cars and car engines, with different displacements, carburettors, flywheel weights, compression, etc. There is engineering in it, but it's ultimately down to a large amount of feeling and careful judgement by experts of where the balance between all the different factors should lie. 

 

Also, refractors, while often theoretically inferior to reflectors, often perform wonderfully well in practice. Reflectors, often theoretically superior, in practice nonetheless struggles to keep up. They nearly always do inch for inch and very often even when given a respectable aperture advantage. This naturally sparks debate and is the sort of thing that creates very strong brand loyalty, or in this case, design loyalty, towards the refractor.  

 

*) There are of course a huge number of reflector designs, but many of them are obscure and people tend to think of a newtonian or a cassegrain, when they hear the word "reflector". 

 

 

Clear skies!
Thomas, Denmark

Hi Thomas,

I see it very similar like you. Almost all of us have Newtons, too and although we have our personal preferences like e.g. refractors we enjoy a nice view in our Newtons, too.

In the winter time I disliked the spice cross on Jupiter but I learned to ignore it.

In the summer time I dislike the tube or local seeing problems during watching Saturn. The tube seeing destroys the high resolution view so I cannot see much details on Saturn, then. Then the evil achromats with 80/1200 or even the more evil 102/1100 achromat can provide more details than the more powerful 150/1200 if it suffers on bad tube seeing.

Coming back to the original question. I have a 102/920 fluorite refractor with only two lenses. I have no ED to compare but I like the colour correction. For me the colours of Jupiter and Saturn is Newton like and it has a higher contrast than the achromats. Currently only Takahashi offers Fluorite refractors so question is rather a doublet from the Japanese company Takahashi or an ED doublet mostly produced in China if you want to have a doublet.

Me I prefer telescopes build outside of China because I hope that the working conditions are better e.g. in Japan than in China and I hope a little bit that the quality spread is lower in Japan. That's more important than ED or fluorite for me. ;)

I think for triplets Takahashi takes ED glass so in this case probably the best decision.

Clear sky,

  Roland


Edited by Niklo, 07 August 2015 - 10:00 AM.


#42 doctordub

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Posted 07 August 2015 - 10:59 AM

Fluorite VS ED, for me that means doublet VS triplet. The Takahashi TOA 150 is more than 10lbs heavier and cost $5000.00 more than my Takahashi  FS 152 NSV for nearly identical views according to most reviews.

I now take out my 6" APO nearly every clear night without much drama. I still can't believe I have this scope after 9 years of wanting it.

CS

Jonathan

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#43 Markab

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Posted 07 August 2015 - 11:11 AM

One thing that is indisputable and does indeed make fluorite special: the Chinese clone companies like Expl@re Scientific do not make it. At least, that makes is special to me.



#44 BillP

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Posted 07 August 2015 - 11:12 AM

 

 

1) They may have a "relationship" but the manufacturing, grinding, polishing, and coating are done elsewhere, they don't "work with fluorite" in any environmentally meaningful way so any environmental concerns are moot.

 

2) I never said Tak gets their fluorite from Germany, please re-read my post. Just pointing out that the eco excuse for switching to FPL53 floated by Tak dealers doesn't seem to have any basis in fact. But after beating the fluorite-is-better-than-FPL53 drum for so many years only to have Tak switch to FPL53 they had to have something to appease the faithful.

 

3) There's what they say and there's what they do. At one time all of Tak's flagship refractors had a fluorite element, now their flagship refractors with the best color correction in Tak history are FPL53 scopes. And Tak dealers have a history of over the top claims on their web sites; for years all the Tak dealers posted a claim that, to be true, would have required competitors' high quality equal aperture scopes to have a light throughput of about 60%, absolute nonsense.

 

 

Well if that is how you view it.  Tak IMO is responsible for their products so they work with it from that aspect.  I am sure environmental concerns are not moot and they have them.

 

On the Germany issue, sorry, but how you wrote your response was difficult to interpret.  I personally think you are reading more into things with Tak then are there, but that is fine.  I don't hold them to any standard where 100% of their products need a Fluorite element to be able to say that they profess a Fluorite Advantage.  I do not consider that reasonable.  So we have differing opinions as I do not see them abandoning anything.  But if you feel that way then fine, we are all free to interpret as we wish. 

 

On what is on websites...well that is just silly...especially at the dealer level.  All dealers are in it for one thing, to make a buck.  So that is what there posted information pays homage to.  I would never trust anything that is marketing...don't care who is making the claim.



#45 Thomas A Davis

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Posted 07 August 2015 - 11:32 AM

There are two refractors that I've looked through (I owned one of them) that provided what I would call a perfect image. One had fluorite, the other not. The one was a TEC 200mm F/8 fluorite triplet, the other an AP180EDT F/9. Both were oil-spaced triplets.

To me, who the chef is matters as much, or more than the ingredients used. Again, the combination of glasses and the design figure makes the best result, not just one element in the design. I've seen no loss of contrast not having fluorite on a premium design. Focusing to pinpoint stars has more to do with producing smooth, well corrected optics than the glass used. Proper glass mating and design matters as well. If there is an issue with the quality of the glass used that comes into this as well. A premium manufacturer may well reject glass someone who is working at a lower price point might accept.

The best color correction I've seen was in a TMB/APM OK-4 130mm F/9.25 triplet. Newtonian level. No fluorite used.

I tend to work with the reputation of the manufacturer more than advertising over glass used. If the scope works, I don't care if window glass is used.

Tom

#46 edif300

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Posted 07 August 2015 - 12:13 PM

3) There's what they say and there's what they do. At one time all of Tak's flagship refractors had a fluorite element, now their flagship refractors with the best color correction in Tak history are FPL53 scopes.

 

 

Once again, this need a clarification.

 

TSA-102 uses one (only one) ED. FCT-100 uses only ONE Fluorite. Both has same grade of real measured polystrehl ratio -as you know where check this-. The FCT is a f/6.4 but not a f/8 as TSA-102 is.

By the way, the better color corrected scope (and not only in Tak history ;) ) employs TWO ED in a triplet.

 

Maybe in future it can be measured other thing.



#47 edif300

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Posted 07 August 2015 - 12:44 PM

 


The eco issue was raised by a Tak European dealer when they were questioned about abandoning the "fluorite advantage." And it's still made in Germany where eco laws are much tougher than in Japan.

 

 

The eco issue or referencing that "all lenses are ECO glass" comes from Takahashi Japan back from 2005 when TOA-150 was introduced. I'm not sure if they also wrote about the ECO glass during 2003 when TOA-130 was introduced -first in using ECO glass- but unfortunately there is no available such old link -or I can't found it-.

 

Here a link from 2005 (TOA-150):

 

http://www.takahashi...0507TOA150.html

 

And here the exact extract (copy/paste):  TOA光学系は、2枚の特殊低分散ガラス(EDガラス)を含む3枚構成の対物レンズ(すべてECOガラス)


Edited by edif300, 07 August 2015 - 12:51 PM.


#48 gnowellsct

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Posted 07 August 2015 - 12:47 PM

Let's face it, refractors are interesting to talk about, because their design, compared to the mirrors of a reflector*, can be almost infinitely variable. Designing and making refractors is almost more an art, than it is engineering. It's like cars and car engines, with different displacements, carburettors, flywheel weights, compression, etc. There is engineering in it, but it's ultimately down to a large amount of feeling and careful judgement by experts of where the balance between all the different factors should lie. 

 

Also, refractors, while often theoretically inferior to reflectors, often perform wonderfully well in practice. Reflectors, often theoretically superior, in practice nonetheless struggles to keep up. They nearly always do inch for inch and very often even when given a respectable aperture advantage. This naturally sparks debate and is the sort of thing that creates very strong brand loyalty, or in this case, design loyalty, towards the refractor.  

 

*) There are of course a huge number of reflector designs, but many of them are obscure and people tend to think of a newtonian or a cassegrain, when they hear the word "reflector". 

 

 

Clear skies!
Thomas, Denmark

 

What sparks debate is that spending so much per inch makes most refractor owners insane.  It's like trying to talk an elephant out of a tree when you don't know what got him up there in the first place.  GN



#49 Lance1234

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Posted 07 August 2015 - 01:15 PM

 

What sparks debate is that spending so much per inch makes most refractor owners insane.  It's like trying to talk an elephant out of a tree when you don't know what got him up there in the first place.  GN

 

:scratchhead:  :elephant:  :lol:



#50 Astrojensen

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Posted 07 August 2015 - 01:20 PM

 

What sparks debate is that spending so much per inch makes most refractor owners insane.  It's like trying to talk an elephant out of a tree when you don't know what got him up there in the first place.  GN

I love refractors and when looking through them, I am constantly reminded why. You could try talking me down from the tree, but I am too busy looking at the universe to listen.  :grin:

 

 

Clear skies!
Thomas, Denmark

 

PS: But I also have a 12" dob. It does a fine job on deep-sky and is a fun scope, I just love refractors more. I spend five times more on my Zeiss Telemator than I did on the 12" and I don't regret it. 




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