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Grumpy Martian

Older Apo refractors with Fluorite optical elements.

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I will be celebrating my ?0th birthday in July. I am looking to have bought for me a fine smaller size refractor, a keeper. This may or may not be a newly purchased model. Looking at the Williams Optics Zenithstar 73mm or 103mm. A transportable setup. I have seen some fine looking older models such as Tele Vue, Takahasi and Vixen. I have always been of the opinion that refractors including those with quality fluorite optics would last for always. But someone once suggested that any refractor approaching fifthteen to twenty years that the fluorite would deteriorate. Is this true? Or can buying such an instrument if well looked after, still be relied upon to be sound? 

Edited by Grumpy Martian
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I don't think there is any evidence for this. There are plenty of Vixen FL102's still in good service and over 20 years old.

 

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This seems to be something that comes up from time to time on astro forums, and based on owner feedback at least, a bit of a urban legend rather than based on fact.  Certainly there are plenty of older models out there still being used under the stars, performing as well as they ever did.  While I do not own any older model fluorite refractors so can only relay what I have read elsewhere, I would not factor that in my thinking if I were looking second hand.  Just with any optical purchase though, a very thorough examination of the scope in person would be preferable to ensure it has been well looked after.

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Happy ?0th birthday - in advance.

From my experience of 'old glass' the main exterior surface problems have been caused by over enthusiastic cleaning.

While a standard specs lens cleaning cloth does no immediate harm, what about after hundreds of cleans?
We all avoid 'soft coated' mirrors but tend to think of lenses as coated with harder stuff, which they are.
But eventually coatings get worn.

I have seen quite a few binos with distinctly foggy views.
I believe this to have been caused by vapours from the grease used in focus assemblies. But have no proof.

I have a Prinz refractor, purchased used by my father in 1987. The objective is still good.
I have the remnants of a Prinz terrestrial scope from the 70s. Again still a good objective.

Hope this helps.

David.

 

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I think my recommendation for a 70th birthday present for yourself might well be to go for a Takahashi FC-100 F/7.4. Lightweight, well made, exquisite fluorite optics :smiley:

Maybe a little more than you were thinking of spending but you are only 70 once !

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Fluorite scopes have been produced for decades and even the older ones are still going strong. There's such a lot of nonsense talked about by the empty headed, and when you think about it, we never see any of these perished fluorite optics. I'm sure I wouldn't be alone in kicking off big style if my fluorite lense suddenly turned into a bad cold and flopped from my tube assembly. Some of the early Takahashi FC refractors that had uncoated fluorite elements are as good today as they were when they were first made, and still demand a high resale price. 

Vixen fluorite refractors used uncoated fluorite elements as the rear element in their Steinheil FL 102, but they are still highly sought after. Personally, I think the FL102 is one of the very best fluorite refractors ever made, bested perhaps by Takahashi's FC100DL F9 which has a hard multicoated rear fluorite element. If you can find a Vixen FL102 F9 then grab it and run. You'll never regret it! Alternatively,  any of the 100mm or 102mm Takahashi fluorite refractors will WOW  you again and again. John already mentioned the Tak FC100DC or DF F7.4 so if a second-hand fluorite doesn't appear, you might consider the light weight but stunning FC100D. 

Edited by mikeDnight
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4 hours ago, John said:

I think my recommendation for a 70th birthday present for yourself might well be to go for a Takahashi FC-100 F/7.4. Lightweight, well made, exquisite fluorite optics :smiley:

Maybe a little more than you were thinking of spending but you are only 70 once !

+1 for a Takahashi FC100 - special pressie for my 60th and absolutely no regrets!! 

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My 21 year old Takahashi FS128 gives terrible views - because it’s lens is made of flour right ?

Jokes aside I have not seen any degradation in the views over the years and it gives superb planetary views.

And I would also suggest the Tak FC 100 is worth looking at (and through 😀)

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Wild horses wouldn't drag me from my old style fluorite Takahashi FSQ to the modern ED 'equivalent.'

Olly

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6 minutes ago, ollypenrice said:

Wild horses wouldn't drag me from my old style fluorite Takahashi FSQ to the modern ED 'equivalent.'

Olly

Now they have 2 ED lenses.  What do the color correction graphs look like?

Rodd

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23 minutes ago, Rodd said:

Now they have 2 ED lenses.  What do the color correction graphs look like?

Rodd

Not a clue, but how do the scopes perform? I use two fine old fluorites and have seen enough new EDs giving hassle here to know that I don't want one. Spent quite a lot of this afternoon trying to analyze problem subs from one which I host. The new Capstan wheel (now abandoned) is another issue. At least they were right to abandon it. It's a prime source of tilt. Refractors should just work. Too many new Tak FSQs just don't. They need a kick in the behind and that's what they're getting from me.

Olly

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I have a 4" Vixen flourite that must be at least 20 years old. Its been used for solar as well as night time, never been cleaned and is our control telescope when judging the collimation and performance of other telescopes.   🙂

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As David says (Dweller 25) about his Tak FS128, my own FS128 looks and performs like new and is also 21 years old this year. Same for it's EM2s TAK mount, flawless. 

I'm sure Vixen, Tele Vue, Lzos, and other good brands using Fluorite or similar glass will do the same. Buy quality, buy once, buy great performance:D

Dave

 

 

 

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Canon have been manufacturing Fluorite elements for their 'L' series camera lenses for many years, I've never heard of any reports of deterioration. I suspect the average paparazzi takes very little care with their lenses! 

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2 minutes ago, MoonStarer said:

Canon have been manufacturing Fluorite elements for their 'L' series camera lenses for many years, I've never heard of any reports of deterioration. I suspect the average paparazzi takes very little care with their lenses! 

Canon Optron make the fluorite objectives for Takahashi and Vixen as well.

 

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