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80mm long FL refractor -- choose but choose wisely

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105 replies to this topic

#76 rob1986

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Posted 31 January 2021 - 05:34 PM

Hi,
I follow the topic closely. I consider a Carton 77mm f 1250 for purchase. Any comment on this refractor?
Regards
Dimitris

I really hope that's supposed to be f 12 point 50.
Otherwise I salue you on your 76 meter long refractor. how are the views? Is it single element?
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#77 mitsos68

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Posted 01 February 2021 - 01:49 AM

 

I really hope that's supposed to be f 12 point 50.
Otherwise I salue you on your 76 meter long refractor. how are the views? Is it single element?



Hi,
Focal length is 1250mm. Its a typical Double achromat. I do not have it ... But I consider the purchase. Model Space77....

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Edited by mitsos68, 01 February 2021 - 02:39 AM.

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#78 Mihai

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Posted 01 February 2021 - 03:47 AM

I suppose those Carton refractors are old stock from Ebay,no?...Or they are available new from Japan?...I have wanted one of those long refractor for a long time :)

#79 Jon Isaacs

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Posted 01 February 2021 - 05:18 AM

Hi Jon! If I may where did you find this information? Or is it a calculation of known data?

Thank you!

 

Clear skies & Good seeing

 

It's based on an equation someone posted here that was derived from an equation from the book Telescope Optics by Rutten and van Venrooii.  

 

Color blur = (735 x Aperture (mm)) / (Focal Ratio x Longitudinal color error)   It's an extension of the Sidgwick and Conrady guidelines.  I use an abbe normal chart that was annotated by Roland Christen on astromart. It requires some interpretation but it should be close.

 

Put in 11000 for the Longitudinal Color error for FPL-53.  

 

Blur = (735 x 100) / (9 x 11000) = 0.74

 

I use 1900 for achromats, 6700 for FPL-51 class doublets. 

 

If you look at Vlad's work on the Polychromatic Strehl, a 100mm F/9 FPL-53 doublet is almost perfect. 

 

https://www.telescop...s/achro_apo.PNG

 

Jon


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#80 PKDfan

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Posted 01 February 2021 - 12:56 PM

My thanks Jon for your explanation!

CS & GS
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#81 mitsos68

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Posted 13 February 2021 - 03:11 PM

Hi.
Yesterday a vintage Carton refractor OTA arrived from Japan. Has 77mm aperture and 1250mm focal length. Serial number 150. No other markings on it. Objective is pristine and the tube has few small scratches. Focuser complex is quite heavy. Any further information on this telescope would be much appreciated. Photos at: https://www.cloudyni...m/15946-carton/
Regards
Dimitris.


Edited by mitsos68, 13 February 2021 - 03:16 PM.

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#82 daquad

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Posted 13 February 2021 - 03:27 PM

Very, very nice.



#83 BarrySimon615

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Posted 14 February 2021 - 11:30 PM

The Milo 76 mm f/18.4 (1400 mm focal length) achromatic doublet has all you would ever want for apochromatic performance in a simple long focal length doublet.  Shown on a Unitron #142 mount.

 

Barry Simon

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#84 BarrySimon615

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Posted 15 February 2021 - 12:03 AM

Here is one for the ages in what is/was a great 80 mm class long focal length achromat - the Unitron #142 3" f/16 doublet achromat.  This photo was our "home page image on the UnitronRefractors Yahoo Group.  This is the only image (excepting my own submitted images to the group) that I salvaged before all Yahoo Groups were taken down.  This image was given to the group by Stefan Seip.  I was the group owner/moderator.

 

Barry Simon

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#85 castorpolu11

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Posted 07 April 2021 - 02:40 PM

ST f/15's back in stock at FLO -- looks like they've got about 10!

 

https://www.firstlig...-refractor.html


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#86 Jim Curry

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Posted 08 April 2021 - 06:25 AM

ST f/15's back in stock at FLO -- looks like they've got about 10!

 

https://www.firstlig...-refractor.html

Wow, optics made in Japan.  That tells me there's probably a high level of care put into the optics.  They claim 200x+ magnification, it sounds like my Zeiss 80mm.



#87 25585

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Posted 08 April 2021 - 07:13 AM

I was going to mention that one as well, but he said ~$700.  The Stellamira is 899 BP's.

FLO are now also selling the Crayford focuser model at a lower price than the R & P focuser model. 



#88 daquad

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Posted 08 April 2021 - 10:36 AM

FLO are now also selling the Crayford focuser model at a lower price than the R & P focuser model. 

Yeah, I saw that.  But, since June/2020 with the US manufacturing money for Covid relief, the value of the US dollar has fallen considerably with respect to the British pound (and the Euro).  So the cost of the Stellamira with the Crayford comes to about $900 with shipping. Too bad.

 

Dom Q.


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#89 JIMZ7

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Posted 08 April 2021 - 02:53 PM

I had half dozen of 80mm scopes. The first a 1972 Meade 80mm f/15. The first year of Meade. All optically the same China and Japan. The current one a Celestron First Scope 80mm f/11.4 made in China but everything metal and black wooden legs on a EQ-2 mount. To me built more like a Japan scope. This one sold in 1996.

Jim


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#90 Nippon

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Posted 08 April 2021 - 04:03 PM

Of the following three options, which would you choose and why:

 

1. Vixen made FirstScope 80mm in excellent shape

2. https://www.firstlig...-refractor.html

3. https://www.vixenopt...ope-p/26062.htm

 

If you wish to select an option not listed it has to be 80mm and no shorter than f/11 and cost no more than $700!

I had a Celestron firstscope 80 and it was a great scope. Optics were first rate. The Vixen A81M is pretty much the same scope. I currently have a Vixen ED103s and can vouge for the fact that Vixen's Japan made scope's optical quality is just as good as it was in the 80s and 90s. I have no experience with the Firstlight model.


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#91 Bomber Bob

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Posted 08 April 2021 - 10:28 PM

I paid $100 for my vintage 1980s Celestron (Vixen JP) C80 Premium (all faces multi-coated) OTA.  I was pleasantly surprised by the views, since it's faster than my outstanding 1964 Sears (ASTRO) F16 that has the push-pull lens cell, while the C80's is fixed.



#92 Nippon

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Posted 09 April 2021 - 12:04 AM

I paid $100 for my vintage 1980s Celestron (Vixen JP) C80 Premium (all faces multi-coated) OTA.  I was pleasantly surprised by the views, since it's faster than my outstanding 1964 Sears (ASTRO) F16 that has the push-pull lens cell, while the C80's is fixed.

I'm surprised your 1980s C80 premium had multi coated optics. My Celestron Firstscope 80 had single layer coatings. At least I believe they were single layer the coatings were a light blue. Didn't stop it from  being sharp with high contrast.


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#93 Bomber Bob

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Posted 09 April 2021 - 10:55 AM

I'm surprised your 1980s C80 premium had multi coated optics.

 

I haven't verified it myself, but the Vixen Fans say that's what the Premium on the label means.  Like my $150 vintage C102, the C80 has an excellent DPAC pattern.

 

Before spending $500+ on a brand new Japan-made 80mm F15, I do some shopping for a well-preserved C80, Carton, Takahashi TS-80, or even a Towa 339.



#94 daquad

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Posted 09 April 2021 - 06:15 PM

I'm surprised your 1980s C80 premium had multi coated optics.

 

I haven't verified it myself, but the Vixen Fans say that's what the Premium on the label means.  Like my $150 vintage C102, the C80 has an excellent DPAC pattern.

 

Before spending $500+ on a brand new Japan-made 80mm F15, I do some shopping for a well-preserved C80, Carton, Takahashi TS-80, or even a Towa 339.

Yeah, but if you can't find them, the price of a new ST f/15 is well worth it, if you are in the market for that type of scope.

 

Dom Q.



#95 MartinPond

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Posted 10 April 2021 - 03:14 PM

I suppose those Carton refractors are old stock from Ebay,no?...Or they are available new from Japan?...I have wanted one of those long refractor for a long time smile.gif

Hehe...from the 50s and 60s.

 

I have to say, that looks nicer than even most refractors from Japan back then!

Truly premium.


Edited by MartinPond, 10 April 2021 - 03:14 PM.


#96 LDW47

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Posted 11 April 2021 - 08:50 AM

Do you have any experience comparing the difference between a vixen made C80 and the later Chinese versions of the firstscope? Of course it's assumed that the Japanese scopes are superior but I'd love to hear from someone who has used both and can comment on the differences first hand. 

Not exactly, mine was the Chinese 102 HD model, Ed Ting rated it highly in his review ! Not trying to deviate from the 80mm scopes, its just you ask a question, lol !



#97 LDW47

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Posted 11 April 2021 - 08:54 AM

I'm surprised your 1980s C80 premium had multi coated optics. My Celestron Firstscope 80 had single layer coatings. At least I believe they were single layer the coatings were a light blue. Didn't stop it from  being sharp with high contrast.

I always thought multi coatings were the standard in the 80’s and on ?? What / where does something tell you differently ??



#98 LDW47

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Posted 11 April 2021 - 09:00 AM

I sure wish I could find a decent 80mm F10 achromatic doublet (not ED) with the ability to go 2" on the focuser. frown.gif

 

Very best,

Why can’t you ? Agena Astro sell various sizes of 2” GSO’s, I put one on my C80 in about 15min. They work perfectly for less than $150 !



#99 Bomber Bob

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Posted 11 April 2021 - 04:21 PM

I always thought multi coatings were the standard in the 80’s and on ?? What / where does something tell you differently ??

Basic MgFl on the crown was standard back then; all 4 faces (crown + flint) wasn't common.  When I ordered my 5" F10 from D&G Optical in 1988, I paid extra to get MgFl on all 4, plus an additional A/R layer on the F1 (crown sky-face) -- can't recall what that chemical was, but all the coatings were done by Scott.



#100 dmgriff

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Posted 11 April 2021 - 05:19 PM

I sure wish I could find a decent 80mm F10 achromatic doublet (not ED) with the ability to go 2" on the focuser. frown.gif

 

Very best,

The Starbase 80 f/10, entry level achro (Japan) sold by Takahashi USA, has a smooth no slop 1.25in r&p. So unless 2in eps are a must, excellent as is. The included alt/az mount is perfectly matched for it, as are the included Starbase orthos (4 element). I checked one out at Land Sea and Sky. Lovely scope. Deserves its proponents on CN. Better than a Vixen A80Mf (China) with a Porta, imo.

 

Good viewing,

 

Dave


Edited by dmgriff, 11 April 2021 - 05:35 PM.

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