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152/1216 fpl-51

Robindonne
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Louis D
Louis D

This diagram from telescope-optics.net gives some idea of the color correction of various glass combinations. Seemingly, an FPL-51 triplet will perform similarly to an FPL-53 doublet at like

dweller25
dweller25

Hey, don’t knock flourite 🙂 here’s the latest image through my 4” 😉

Stu
Stu

I think a fluorite doublet takes some beating, certainly for visual, but suspect that any of the top notch triplets from Tak, LZOS, AP or TEC would be pretty hard to separate, whether they contain flu

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Robindonne

Robindonne

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I swapped and changed a lot in my shopping cart.  The esprit 120 was constant switching its place with the 150.   The 120 was 90% the favourite one, mostly because its price and the upgrade from my current refractor. I use an equinox 120.  Considering to use that 120 doublet for AP would bring me in the same non-real-apo Photography as technosky 130 fpl-51. So that Technosky is not what i hoped it would be. (Nice aperture though) 

The next purchase must be a scope that performs for both 90%Ap and 10%visual use.  

Maybe the esprit is still an option, or indeed a used Tak.  

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Deadlake

Deadlake

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1 hour ago, jetstream said:

I might have to disagree a bit.  With quality optics its not an issue and espc with the likes of Vixen HR in the mix.

How many 2 to 2.4 mm EP’s out there? Ok Barlow it is then.😀

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jetstream

jetstream

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3 hours ago, Deadlake said:

I’ll find out but how many 2 to 2.4 mm EP’s out there? Ok Barlow it is then.😀

You know, a Nagler 2-4 zoom or the 3-6 zoom (I have this one) is a very good addition. They are sharp- not Vixen HR sharp but sharp.  The Zeiss and Leica zooms with the VIP are very good too. I'll not be with out a Nagler zoom, just to da m handy.

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mikeDnight

mikeDnight

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13 hours ago, Adam J said:

I would not think so, fluorite is not that much better than FPL53 and worse in some ways. More likely it would be on par with a FPL 51 triplet.

Adam

According to Takahashi, Fluorite is "many orders of magnitude better than any ED glass." Whatever that means. Laboratory grown Fluorite crystal is also just as tough as many other optical glasses. The hydrophobic nature of fluorite is grossly over emphasized by some, and is generally more applicable to naturally occuring fluorite. I once placed two pieces of naturall fluorite in a sealed container full of water, and after draining the water away around six months later, they appeared to be totally unchanged. The specimens certainly hadn't broken down or turned to jelly. Plus, modern fluorite lenses made by the likes of Takahashi are hard multi coated, and even the old early FC's and Vixen FL102's that had uncoated fluorite elements are still going strong four decades later.

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Adam J

Adam J

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26 minutes ago, mikeDnight said:

According to Takahashi, Fluorite is "many orders of magnitude better than any ED glass." Whatever that means. Laboratory grown Fluorite crystal is also just as tough as many other optical glasses. The hydrophobic nature of fluorite is grossly over emphasized by some, and is generally more applicable to naturally occuring fluorite. I once placed two pieces of naturall fluorite in a sealed container full of water, and after draining the water away around six months later, they appeared to be totally unchanged. The specimens certainly hadn't broken down or turned to jelly. Plus, modern fluorite lenses made by the likes of Takahashi are hard multi coated, and even the old early FC's and Vixen FL102's that had uncoated fluorite elements are still going strong four decades later.

In what perametre is it hundreds of times better than FPL-53? Otherwise that sounds like marketing nonesense. The problem is it can shatter along the crystal lattice, have seen it happen. It is harder to polish a crystal in comparison to an amorphous material. I am not saying it's not great stuff. Just it's not a miracle material either.

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dweller25

dweller25

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58 minutes ago, JeremyS said:

I was getting fed up with that overrated fluorite stuff, so I went for the TSA to get away from it 😊

Hey, don’t knock flourite 🙂 here’s the latest image through my 4” 😉

5A24AD51-0E3E-4C0F-876F-D9193F22E7F9.thumb.jpeg.62e515185de685c7fa35df740f49a1d7.jpeg

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Stu

Stu

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2 hours ago, jetstream said:

You know, a Nagler 2-4 zoom or the 3-6 zoom (I have this one) is a very good addition. They are sharp- not Vixen HR sharp but sharp.  The Zeiss and Leica zooms with the VIP are very good too. I'll not be with a Nagler zoom, just to da m handy.

I’m sure they are not quite up with the Vixen HRs as you say Gerry, but I have both 2 to 4 and 3 to 6mm Nag zooms and they are very handy, and plenty good enough for my skies! If I get somewhere with better seeing at some point I may change this view but will keep the zooms. A 24mm Panoptic, Leica Zoom, AP Barcon and Nag zoom cover most bases for travelling or even just a minimal set for use at home.

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mikeDnight

mikeDnight

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2 hours ago, Adam J said:

In what perametre is it hundreds of times better than FPL-53? Otherwise that sounds like marketing nonesense. The problem is it can shatter along the crystal lattice, have seen it happen. It is harder to polish a crystal in comparison to an amorphous material. I am not saying it's not great stuff. Just it's not a miracle material either.

I don't believe anyone said fluorite was hundreds of times better than FPL53, but it is better.  I've never seen any fluorite lens, that's been handled with the usual care of any refractor, shatter. If you ever fancy dropping a crown & flint objective against a hard surface, you'll find the flint element will be just as prone to shatter or flake. It does take more care to form, grind, polish and figure fluorite, hence the greater cost, but Takahashi, Canon Optron and numerous others must think its well worth the effort, otherwise they'ed take the easier option.  Really, if fluorite was such a fragile material, no one would use it or want it. And this would extend into the camera and telephoto lens community too, where telephoto lenses can cause the cost of a fluorite telescope to pale into insignificance. Fluorite is not a miracle  material, but it does allow a doublet to perform like a top class triplet. Fluorite lenses also allow for brighter images than other glasses. The use of fluorite isn't marketing nonsense but simply a high quality material alternative that has several advantages over other glass types. 

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Deadlake

Deadlake

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3 hours ago, mikeDnight said:

According to Takahashi, Fluorite is "many orders of magnitude better than any ED glass." Whatever that means. Laboratory grown Fluorite crystal is also just as tough as many other optical glasses. The hydrophobic nature of fluorite is grossly over emphasized by some, and is generally more applicable to naturally occuring fluorite. I once placed two pieces of naturall fluorite in a sealed container full of water, and after draining the water away around six months later, they appeared to be totally unchanged. The specimens certainly hadn't broken down or turned to jelly. Plus, modern fluorite lenses made by the likes of Takahashi are hard multi coated, and even the old early FC's and Vixen FL102's that had uncoated fluorite elements are still going strong four decades later.

So no fungal infections then. if you bought the Russian fluorite lens you could of left your 150 mm scope in your observatory. 😀 

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