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AT72EDii has changed to FCD100 from FPL53

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#1 khursh

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Posted 21 May 2020 - 09:18 AM

I am probably making more out of this than I should, but I ordered at AT72EDii some time ago and have been (not-so) patiently waiting for this well thought after refractor to compliment my Orion EON 120 ED scope. My Orion is also a doublet with an FPL-53 and is really nice for the money I paid. I ordered the Astro-tech based on my experience with this type of glass. I have a sense of trust, if you will, that if I ordered another scope with the same glass, and decent reviews, I will get similar performance. I was informed yesterday that the glass has been changed to FCD100. From everything I read, which is again probably too much, the glass is very similar. Should I cancel my order, since I DID order the scope based on the previous specs? Also, I am concerned about the resale differential. Maybe this is just the bargain hunter in me, but I feel that FPL-53 labelled scopes have more cache and hence better resale value should I eventually decide to trade up.

 

Just for reference: I am a middle of the road EAA astronomer and budding astrophotographer. I know there is no perfect system, but I do want to be able to image some wide field objects with the little guy. Thanks for any input folks.


Edited by khursh, 21 May 2020 - 09:18 AM.


#2 Doug Culbertson

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Posted 21 May 2020 - 09:20 AM

Still uses FPL-53. https://www.cloudyni...edl/?p=10204204


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#3 aa6ww

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Posted 21 May 2020 - 09:34 AM

Either glass should be excellent. The differences only mater when you're in one of these forums. In the real world when you are using your scope under dark skies, both will be excellent.

 

...Ralph


Edited by aa6ww, 21 May 2020 - 05:20 PM.

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#4 MalVeauX

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Posted 21 May 2020 - 09:37 AM

Hrm,

 

If someone knows what FPL53 is when shopping for glass, they should also be aware of FCD100 or other glass that are equivalents in terms of correction. So it really shouldn't matter.

 

It's not like they're pure fluorite crystals.

 

Very best,


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#5 bobzeq25

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Posted 21 May 2020 - 10:12 AM

Perhaps a small decrease in quality, insignificant to anyone buying a $469 doublet.



#6 khursh

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Posted 21 May 2020 - 10:16 AM

Thanks everyone.

 

I know I sound crazy, but yesterday it was changed to FCD100. I guess they changed it back today. Weird



#7 BFaucett

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Posted 21 May 2020 - 10:19 AM


 

Now, in case people here don't bother to click on the provided link above, here's this:

 

Astronomics wrote:

That was a language barrier issue on my side.  The 72 and 60 still use FPL-53 and Lanthanum combo.  They have since they were introduced.  I am fixing the website currently to reflect the glass type...again.

 

Screenshot of the website on 5/21/2020 at 10:15 am CDT:

 

at72edii-glass.jpg

 

https://www.astronom...fpl-53-f-6.html

 

Bob F. 


Edited by BFaucett, 21 May 2020 - 10:55 AM.

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#8 BFaucett

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Posted 21 May 2020 - 10:23 AM

Thanks everyone.

 

I know I sound crazy, but yesterday it was changed to FCD100. I guess they changed it back today. Weird

 

You're not crazy, I also saw it very early this morning (5/21/2020) on the Astronomics website.

 

BTW, I also have an AT72EDII on order. I'm truly looking forward to receiving it! th_blissysmile.gif

 

Bob F. smile.gif


Edited by BFaucett, 21 May 2020 - 10:48 AM.


#9 khursh

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Posted 21 May 2020 - 10:31 AM

Yep. Me too Bob. Thanks for the info


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#10 BFaucett

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Posted 21 May 2020 - 10:51 AM

From my browser's history:

 

 

my-log-2.jpg

 

Edit to add: Click on the pic for a larger image.

 

Bob F. smile.gif


Edited by BFaucett, 21 May 2020 - 11:07 AM.


#11 SteveG

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Posted 21 May 2020 - 11:49 AM

See this thread. They’re working on it. Language barrier.

https://www.cloudyni...2-new-at102edl/



#12 johrich

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Posted 21 May 2020 - 11:58 AM

I have had an AT72EDII for the past several years and you will love it.  For comparison, I have a Stellarvue SV102 Access (also a doublet, now out of production) with FCD 100 glass.  Both scopes provide great images and to me their clarity and CA correction has to be near if not equal to a triplet with a lesser ED glass type.

 

johrich



#13 DeanD

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Posted 22 May 2020 - 02:12 AM

Even though this appears to be a simple language mix-up, just for interest I looked up the relevant refractive indexes:

 

FCD100 https://refractivein...FCD&page=FCD100  n=1.439

FPL-53 https://refractivein...-FPL&page=FPL53  n=1.437

 

- and the extinction coefficient and all the other derived constants seem to be similarly close

 

Hmmm  wink.gif

 

I suspect you will find that with characteristics that close the actual view, including the CA correction, is dependent much more on the actual quality of the glass (ie: the inclusions etc), the quality of the final polish/figure, and the matching with the Lanthanum element. So, all these being equal, I would be incredibly surprised if anyone could genuinely pick the difference if they had actually changed the glass as first thought...

 

All the best,

 

- Dean


Edited by DeanD, 22 May 2020 - 02:12 AM.

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#14 Erik Bakker

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Posted 22 May 2020 - 04:36 AM

Kevin,

 

This type of concern comes up quite regularly, fueled by marketing and the fact that we are scope users, not scope/optics designers.

 

Focus on the quality of the scope and the optics, NOT on FPL-53 or FCD100, as in itself it says little about the quality of a scope.

 

Just call Mike Bieler at Astronomics if you have any concerns, he is the source for this scope and knows his stuff very well.

 

FYI, high-end telescope designer and manufacturer Roland Christen of Astro-Physics uses FCD100 in his new 92mm StowAway and has this to say about these different glass types and I quote:

 

"On the other hand, the high end SD (Super-ED) glass such as FPL53, FPL55 and FCD100 are inherently high grade because they are delicate glasses to produce and must be very carefully annealed in order to prevent breakage and de-vitrification during melting. In all the years that we used this type of glass in our triplet lenses we have not seen any internal defects or variations of refractive index." If interested, you can find his full view on this here.

 

That said, this is a no brainer. You can stop reading about glass types and enjoy that new AT72EDII that is hopefully coming soon to your doorstep!


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#15 RadioAstronomer

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Posted 22 May 2020 - 06:25 AM

Thought I'd contribute with a meme in case this thread turns into a can of worms.

Attached Thumbnails

  • Screen Shot 2020-05-22 at 4.23.26 AM.jpg

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#16 doctordub

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Posted 22 May 2020 - 07:15 AM

funnypost.gif

CS

Jonathan



#17 Auburn80

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Posted 22 May 2020 - 07:34 AM

The FCD100 AND FPL53 pics should look the same.
😁
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#18 25585

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Posted 22 May 2020 - 07:39 AM

The TS equivalents are still FPL-53. 



#19 Astronomics

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Posted 22 May 2020 - 09:24 AM

It was a language barrier when getting new information on the 102EDL.  I made the change to be as transparent as possible since people ask almost daily about glass types, then changed it back when I worked out the issues with the supplier.


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