63 replies to this topic

[jag767]

Does Astro-Physics, Takahashi or TEC provide optical reports? I don't know about TEC and Tak, I have never heard in an interferogram from either but I could be wrong. An optical report is a piece of paper, the quality of the report depends on who did the testing and how the testing was done. It's a matter of trust that the testing and analysis was done right. If you trust the testing was done right, then trusting that the fabrication and finishing was done right follows.

When you buy a Corvette, you get the specs, that analogous to getting the aperture, the focal ratio, the ED glasses used. But unless things have changed, you don't get an individual dyno-test of the rear wheel horsepower of the vehicle. That would be analogous to the optical test of a refractor.

Jon

Buy a zr1 corvette, they'll even let you go build your own motor. Also, its a lot easier to dyno a car than test a refractor, and 5 of the same car will have a lot less variance that 5 fracs will.

[25585]

Mine is one of the original ones that doesn't say Evostar and has the Schott" label. Mine was sold as a package that came with a mount. These versions had the rounded dew shields where they match up with the OTA vs the squared off ones.
I wonder if like everyone else, they are moving away from FPL-53 glass because of the shortage of this glass I see happening now.

...Ralph

UK still has as yours https://www.firstlig...pro-outfit.html

https://www.365astro...ractor-OTA.html

[25585]

 

I am not a big fan of the build, of the paint colors but I am a big fan of the optics.  That why I went with the Orion 120mm Eon.  It's the 120mm F/7.5 Skywatcher optics in a Long Perng OTA.  No goofy colors, just good old black. (It's actually a gorgeous gloss black with chrome siver trim)  A nice sliding dew shield, machined tube rings, a machined rotating focuser, I consider it one of the best looking scopes one can buy.  A little to flashy to be classic but mechanically it's a very nice scope that is an excellent performer.

 

 

 

 

My friend painted up his Orion ED-100 and added an old WO focuser I had.  

 

 

 

To my eye, that's the best looking ED-100 I've ever seen and Orion/Skywatcher could have chosen a similar paint scheme and had themselves a beautiful looking scope.

 

Jon

 

 

Your Eon was the SW branded Equinox.  https://www.365astro...ractor-OTA.html

 

Great OTA design, I have the 120, 100, 80 & 66. The smaller 2 do not advertise the glass & a ED80 Pro is said to have better performance, slower but less CA, than the Equinox 80mm.

 

A shame SW have only kept sliding dew shields on their Esprit models.  

[25585]

I don't get it. People seem perfectly willing to spend huge bucks on premium brands that don't tell you what they use but demand that economy brands reveal every detail.  

 

It is because they are economy brands people need reassurance. I buy power tools with Honda or Briggs & Stratton motors. Other nondescript makes may be as good or better, but reputation for established reliability counts for a lot.    

 

Upmarket makes like Stihl, you hope the whole is good, the same goes for refractors, less need to know because of overall trust. 

[Jon Isaacs]

Buy a zr1 corvette, they'll even let you go build your own motor. Also, its a lot easier to dyno a car than test a refractor, and 5 of the same car will have a lot less variance that 5 fracs will.

 

But that begs the question.. are you getting the specs or the actual performance. And I wonder what the chances are of two different dynos agreeing to within 3%..

 

And then, the three premium scopes I mentioned, do you get test results. How about Zeiss?

 

Jon

[Jond105]

My Sky-Watcher 120ED, purchased this year. No specs labeled on the OTA, if that’s not FPL-53 glass in there, for as nicely corrected as it is, I want my money back for the cheaper glass. Chances are, it’s FPL-53, labeled or not. 

[Nippon]

This is how I see it:

 

- Premium brands are known quantities.  They're not in a competitive marketplace, you know what you are getting.  TeleVue makes 5 basic telescopes, the TV-60. The 76, 85, NP-101 and the NP-127.  The most recently introduced models were the TeleVue 127 and TV 60 were 2003, they've been making these same basic telescopes with minor modifications for 16 years..  There are no hidden surprises.  It doesn't take a optical guru to figure out that the doublets are using FPL-53 or something very similar, you couldn't get the color correction with FPL-51 type glasses.  

 

- Mid level and entry level scopes are a different story.  They are more of a commodity, they are manufactured in a relatively small number of factories and the name of the end seller is pasted on the OTA along with some minor mechanical and possibly optical variations and that's your scope.  Very often there are FPL-51 and FPL-53 versions of the same scope.   

 

- Did you want to buy the Orion version of the 130mm F/7 FPL-51 triplet for $3000 when someone else was selling the same basic scope for under $2000?  On the other hand, if you are price shopping for a TeleVue 85, there are many choices that will save you more than a $1000 but you won't be getting that same build quality and design.  You buy a TV-85 because that's the scope you want and you are willing to pay a premium for it. 

 

- I think it helps the seller to know what glasses are used.  Prior to the introduction of the ED-80 by Orion, Orion had sold at least one ED-80 but it was based on FK-5 and essentially an achromat.  Knowing that the ED-80 was using the same ED glass as Astro-Physics went a long way in developing the market for the ED-80.. It wasn't just another fake ED scope.

 

Jon

Those are good points. Most of the mid level and low level offerings on the market these days seem to offer performance well worth their selling price. One of the first things I read about 30 years ago was you get what you pay for. But the Synta made ED scopes have consistently performed well above their price point. I don't think Synta would  cheapen them just to increase their profits a small amount. If they have changed glass types I would think it would be to something equivalent that they can get a better deal on to keep the selling cost low. But those green anodized parts...someone should  have a talk with them about that:) 

Edited by Nippon, 19 September 2019 - 06:24 PM.

[CHASLX200]

But that begs the question.. are you getting the specs or the actual performance. And I wonder what the chances are of two different dynos agreeing to within 3%..

 

And then, the three premium scopes I mentioned, do you get test results. How about Zeiss?

 

Jon

No dyno will be the same as weather will make numbers vary alone.  Done enough dyno tunes to know. I had two SW120 ED's and the last one was the best.  

Edited by CHASLX200, 19 September 2019 - 06:38 PM.

[SteveG]

There was quite the little fuss about the new Astro Physics 92 Stowaway.  I believe AP uses Hoya FCD100 glass which is supposed to be the equivalent to O'hara FPL53. But that is not what all the fuss was about. No it was because the lens coatings were green so some suspected the optics were made in China for AP. It can all get quite sily in my opinion.

And as I recall, there was quite the fuss over the font used on the focuser, LOL.

[25585]

There was quite the little fuss about the new Astro Physics 92 Stowaway.  I believe AP uses Hoya FCD100 glass which is supposed to be the equivalent to O'hara FPL53. But that is not what all the fuss was about. No it was because the lens coatings were green so some suspected the optics were made in China for AP. It can all get quite sily in my opinion.

Don't get that. The very Japanese TSA120 has green lenses. Maybe the AP lenses were made by Canon?   

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[BillP]

As of the Evostar 150 ED, I thought Skywatcher wasn't revealing glasses anymore.. .

 

I am not surprised.  Their policy change didn't say they would never reveal glass types.  The 120 ED is long-in-the-tooth so not giving anything away revealing its types.

 

For reference, here is their policy as posted by Skyward_Eyes on 13 February 2018:

 

Sky-Watcher will not always state the types of glass and glass combinations used in their various APO telescope designs. We ask for your understanding in this regard because it is through this confidential design and manufacturing information, arrived at with skill and extensive research, which makes our products so successful. As always we would prefer the performance of any particular Sky-Watcher telescope to speak for itself.

[Nippon]

Don't get that. The very Japanese TSA120 has green lenses. Maybe the AP lenses were made by Canon?   

Exactly. My very Japanese Vixen ED 103 has green coatings.

[SandyHouTex]

As I understand it FPL-53 is basiclly a drop in replacement for fluorite.  According to “Telescope Optics” by Rutten and van Venrooij, when designing an APO doublet you want materials that are as far apart on the P-V diagram as possible (Figure 21.14).  Fluorite and FPL-53 are as far left as you can go.  That’s why FPL-53 is so highly prized.

[gnowellsct]

If a small number of manufacturers are bidding on a limited supply of glass, it makes sense to keep your design proprietary to reduce the number of others bidding for your preferred matching elements.

What you do and don't reveal "depends" on your perception of supply. The industry wide movement to 53 was enough to push up price but not enough to incentivize larger production runs because apparently the astro market works within industy trends but does not drive them.

I am willing to believe a CFF with 55 would be a wicked good scope. I'd buy one but I'm running out of money and short of time.