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New WO73 fpl53 glass.

Chris

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Chris

Chris

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22 minutes ago, xtreemchaos said:

its all melted sand to me, when thay put all fancy names in front of the word glass thay might as well be talking Klingon :help:. charl.

This pretty much sums up all I know, charl lol

Ohara FPL-53 vs FPL-51 ED Glass

The dispersion properties of ED and SD glass elements are important in determining the overall colour correction. The abbe index is used to quantify the 'partial dispersion' of a particular glass. Pure Fluorite offers the highest partial dispersion at around 94.99 V, Ohara FPL-53 glass is very close to Fluorite at 94.93 V and is often referred to as Synthetic Fluorite.  FPL-53 is also noticeably better than Ohara's lower spec' FPL-51 glass which offers an abbe index of 81.54 V.

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alexbb

alexbb

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Saw it yesterday, quite surprised that it took so long for the first topic :D

No word about the flattener yet. The price seems to be about the same as for the ZS71 which has FPL 51 glass. Might work with the flattener designed for the 71, though they might design a new one.

A lot of options lately for high quality short focal length scopes.

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John

John

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I believe that Ohara are due to phase out FPL-53 glass in the not too distant future. Some manufacturers are already planning on moving to other glass types in their doublets and triplets.

It's been hard to keep up with the William Optics range of scopes over the years :rolleyes2:

The only one I've owned was a Megrez 90 which also used an FPL-53 element in a doublet objective. Unusually I bought that new but it depreciated quite quickly !

 

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Chris

Chris

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7 hours ago, John said:

Unusually I bought that new but it depreciated quite quickly !

This seems to happen with all the scopes I buy new. Definately pays to buy second hand where possible unless you at least get a fair bit of use/fun from a scope before selling.

My latest example of this is my 150p dob, bought for £209 and it's not looking like selling for just £100. Just like cars that lose 2K just by driving them off the forecourt hey :rolleyes:

7 hours ago, John said:

I believe that Ohara are due to phase out FPL-53 glass in the not too distant future. Some manufacturers are already planning on moving to other glass types in their doublets and triplets.

I heard this, and I'm not sure how the new glass will compare or what it is even? FCD100 perhaps? I know the planned SW ED150 won't have fpl53, I think you may have told me this even.

Congratulations on being a Mod again by the way, I noticed the other day :)  

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8 hours ago, John said:

I believe that Ohara are due to phase out FPL-53 glass in the not too distant future. Some manufacturers are already planning on moving to other glass types in their doublets and triplets.

It's been hard to keep up with the William Optics range of scopes over the years :rolleyes2:

The only one I've owned was a Megrez 90 which also used an FPL-53 element in a doublet objective. Unusually I bought that new but it depreciated quite quickly !

 

That could be dissappointing John the news that they are phasing out FPL 53 glass. Just when I got to an understanding of what to expect with colour correction when looking at various refractors and the type of glass that they used. I know that  when have I have owned refractors with FPL 51 glass  lots of colour was seen viewing brighter objects. This was so with some other types of glass aswell. So just wondering why they would stop using 53 glass?  Would they use an equivalent with similar good properties as FPL 53?

It was always accepted that Skywatcher gave very good value in quality versus price compared to other manufacturers telescopes. Now that they are established surely they are not going to use cheaper components to save on manufacturing costs. Or have I got it wrong.

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Chris

Chris

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51 minutes ago, Grumpy Martian said:

Nice post Chris. How you keeping.

Hi Martin, good thanks, nothing bad to report which is always something to be thankful for :) Snowing quite heavily today so the kids are excited. More so than myself, I'm feeling a bit sleep deprived today lol. How things with yourself?

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John

John

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On 10/12/2017 at 09:31, Grumpy Martian said:

That could be dissappointing John the news that they are phasing out FPL 53 glass. Just when I got to an understanding of what to expect with colour correction when looking at various refractors and the type of glass that they used. I know that  when have I have owned refractors with FPL 51 glass  lots of colour was seen viewing brighter objects. This was so with some other types of glass aswell. So just wondering why they would stop using 53 glass?  Would they use an equivalent with similar good properties as FPL 53?

It was always accepted that Skywatcher gave very good value in quality versus price compared to other manufacturers telescopes. Now that they are established surely they are not going to use cheaper components to save on manufacturing costs. Or have I got it wrong.

My understanding is that Ohara are going to stop making FPL-53 glass so Skywatcher and all the other brands who currently use it will be affected. There are very, very few companies that actually manufacture optical glass - LZOS is the only one that springs to mind that also makes objective lenses.

 

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FLO

FLO

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54 minutes ago, John said:

My understanding is that Ohara are going to stop making FPL-53 glass

There are two or three rumours going around atm, I wish I knew which one was true. 

Currently, we think Ohara will release a new higher grade glass (closer to genuine fluorite, which is the material they are all emulating). If we are right then FPL53 (we assume) will replace FPL51 for entry-level ED scopes and new higher performing models will be announced.  

We could be wrong... :smile: 

Steve 

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FLO

FLO

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Regarding the new William Optics Zenithstar-73 with FPL53 glass, in theory (it is nearly Christmas) our first delivery will arrive in approx one week. 

As for the Zenithstar-71 with FPL51 glass, we think the Zenithstar-73 has essentially replaced it. 

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FLO

FLO

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3 hours ago, FLO said:

I have made some enquiries. 

Ultimately only Ohara know for sure but, from what I am hearing in the industry, FPL53 is hear to stay. 

Unless we hear otherwise we are predicting FPL53 will, essentially, replace FPL51 as the entry-level ED glass and a new higher specification glass (perhaps 'FPL55') will be released. 

HTH, 

Steve 

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Chris

Chris

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7 minutes ago, FLO said:

Unless we hear otherwise we are predicting FPL53 will, essentially, replace FPL51 as the entry-level ED glass

This does seem to fit with the WO73 fpl53 possibly replacing the ZS71 fpl51.

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25585

25585

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Interesting reading Wikipedia on these rare earth metals. 

Lanthanum Oxide, which I looked up, can be combined with Flourite etc. 

How much of how much is not stated, but synthetic says cheaper, & possibly enhanced from natural processes. 

Synta want to catch up with Takahashi & establish a rival range I expect. The question is will their 150 doublet be as good as their 150 Esprit triplet, for visual at least. The latter's quality hopefully will not be compromised. Doublet may be a longer FL & larger fr as comparing SW 120s. 

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FLO

FLO

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The ED element is only part of the story, the matching Crown element is equally as important and manufacturing quality is, arguably, most important. There are doublets that out-perform triplets, and triplets with FPL51 that out-perform similar models using FPL53. 

Buying a refractor that boasts a particular ED element, that doesn't mean you are out of the woods. 

Steve 

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