Achromat Vs Semi-APO Vs APO - What's The Difference?
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
Thanks for the links, good reference material to read up with not just one beverage but a couple. My only experience in optics at the amateur level is I only made a dozen parabolic mirrors for Dobs and Newts, largest was an 18".
BTW, I see your in HI, I used to do projects for HECO so I made several flights to HI from ATL back in 2006 - 2012.
Joe
Co-owner of RCOS 16" (Snowflake, AZ)
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
The doublet plus singlet became a widespread design for the fast (
With the increasing
Otherwise, even an achromatic doublet can offer an "apochromatic performance" in the eye relief space behind the eyepiece, when the eyepiece is overcorrected to flip the focus deviations on the short wavelengths, and in the way like the yellow curve in the graphic I have posted before.
But even then, outside the range of the three crossings, the deviations will be much larger if compared with a true
Best,
JG
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
I have nothing to add but my thanks to the chef, Mr JT, who set the table for this conversation.
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
That made me lost, as i rushed buying first
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Surely, you can just look at what it says it is, on the box that it came in, right??notFritzArgelander wrote: ↑Sat Aug 17, 2019 10:15 pm Thanks for posting this. It's sane. It also shows that the "double versus triplet" distinction is not meaningful. It's an oversimplification of a more complex problem. You need to look at the aberrations to see if your instrument is or is not an apochromat. It's not as simple as counting the number of elements in the objective!
:eek: :twitch:
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Yes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pmSurely, you can just look at what it says it is, on the box that it came in, right??notFritzArgelander wrote: ↑Sat Aug 17, 2019 10:15 pm Thanks for posting this. It's sane. It also shows that the "double versus triplet" distinction is not meaningful. It's an oversimplification of a more complex problem. You need to look at the aberrations to see if your instrument is or is not an apochromat. It's not as simple as counting the number of elements in the objective!
:eek: :twitch:
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Maybe i won't go to that much elements, so eliminate one element, how about a quintuplet then?notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pmYes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pmSurely, you can just look at what it says it is, on the box that it came in, right??notFritzArgelander wrote: ↑Sat Aug 17, 2019 10:15 pm Thanks for posting this. It's sane. It also shows that the "double versus triplet" distinction is not meaningful. It's an oversimplification of a more complex problem. You need to look at the aberrations to see if your instrument is or is not an apochromat. It's not as simple as counting the number of elements in the objective!
:eek: :twitch:
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Well, maybe not, in every case, for telescope objectives. But for eyepieces, more lenses is always better! On that, we all surely agree....notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pmYes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pmSurely, you can just look at what it says it is, on the box that it came in, right??notFritzArgelander wrote: ↑Sat Aug 17, 2019 10:15 pm Thanks for posting this. It's sane. It also shows that the "double versus triplet" distinction is not meaningful. It's an oversimplification of a more complex problem. You need to look at the aberrations to see if your instrument is or is not an apochromat. It's not as simple as counting the number of elements in the objective!
:eek: :twitch:
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
https://agenaastro.com/sharpstar-121mm- ... 21sdq.html
And... sextuplets? Seriously?
https://telescopes.net/store/stellarvue ... graph.html
(Ok, so that isn't intended for visual astronomy. But still...)
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Yes, I know that I must be hallucinating when I am sure that my 1+3 element Abbe Orthoscopic eyepieces dive better contrast and definition than a gazillion element wide field.AntennaGuy wrote: ↑Sat Jan 30, 2021 8:23 pmWell, maybe not, in every case, for telescope objectives. But for eyepieces, more lenses is always better! On that, we all surely agree....notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pmYes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pm
Surely, you can just look at what it says it is, on the box that it came in, right??
:eek: :twitch:
(I know you're cranking me up so I might as well play along and do my straight man schtick.)
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
A quintuplet is a good solution.TareqPhoto wrote: ↑Sat Jan 30, 2021 7:50 pmMaybe i won't go to that much elements, so eliminate one element, how about a quintuplet then?notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pmYes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pm
Surely, you can just look at what it says it is, on the box that it came in, right??
:eek: :twitch:
A sort of is my leica
So any fast good
In plain langueage: Any good refractor should be *tuplet, and not just *let
Best,
JG
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
A quintuplet is a good solution.TareqPhoto wrote: ↑Sat Jan 30, 2021 7:50 pmMaybe i won't go to that much elements, so eliminate one element, how about a quintuplet then?notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pmYes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?AntennaGuy wrote: ↑Sat Jan 30, 2021 4:57 pm
Surely, you can just look at what it says it is, on the box that it came in, right??
:eek: :twitch:
A sort of is my Leica
So any fast good
In plain langueage: Any good refractor should be *tuplet, and not just *let.
Best,
JG
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
I just talked to my wallet. He grinned and told me to go to the wife.j.gardavsky wrote: ↑Sun Jan 31, 2021 8:23 pm In plain langueage: Any good refractor should be *tuplet, and not just *let.
Best,
JG
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference
Don't know which post of this double post i should quote, but it doesn't matter.j.gardavsky wrote: ↑Sun Jan 31, 2021 8:23 pmA quintuplet is a good solution.TareqPhoto wrote: ↑Sat Jan 30, 2021 7:50 pmMaybe i won't go to that much elements, so eliminate one element, how about a quintuplet then?notFritzArgelander wrote: ↑Sat Jan 30, 2021 5:56 pm
Yes! Everyone knows that "triplets are better than doublets" so lets ditch the trips and get sextuplets! As long as I have fingers and toes to count elements, that's all that matters, right?
A sort of is my LeicaAPO Televid 82mm: 4 lenses in the light gathering groups, and the fifth lens is the field flattener for the ultrawide 80° aspheric zoom.
So any fast goodAPO refractor should have 4 lenses plus a field flattener, when the intended use is with the ultrawide eyepieces.
In plain langueage: Any good refractor should be *tuplet, and not just *let.
Best,
JG
PS : I forgive the 6th lens in the Leica, as it is just the internal focuser.
Well, there is that scope of quintuplet, i don't know if those two elements or 1 is the flattener actually, because this scope also has a reducer to be used, so now how many glasses it will be there? won't that affect the quality with more glasses and then filters?
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
And a Barlow in order to dub' lit.
But it didn't do well,
in regard to the Strehl,
so I traded it for a sextuplet!
:Clap:
(Yes, I plan to keep my day job. For now.)
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
Not bad though!AntennaGuy wrote: ↑Thu Feb 25, 2021 12:35 am O', I bought a refractor quintuplet,
And a Barlow in order to dub' lit.
But it didn't do well,
in regard to the Strehl,
so I traded it for a sextuplet!
:Clap:
(Yes, I plan to keep my day job. For now.)
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
CS
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
Celestron C11 Carbon Fiber CGEM II Mount AKA Cloudzilla
Sky Watcher Mak Cas 180 Ioptron IEQ 30 AKA MoonZilla
AT 92 on IEQ 30 Pro AKA ClusterZilla
Home Made 8 inch Newtonian Reflector on Rocker Box AKA Scopezilla
Celestron 4 1/2 114 mm Newtonian Telescope 910 F/L GT Mount AKA Frankenscope.
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Re: Achromat Vs Semi-APO Vs APO - What's The Difference?
As a person who has used mirrors, achromats, EDs, fluorites..and eventually long achros, I'd say the term is rather flexible in the field. Personally, I'd just stick to Roland Christen's definition: "bringing 3 wavelengths to a common focus and be corrected for spherical aberration at two wavelengths."
Refractors: Tak FC60NZ, Vixen custom 60/910, Vixen FL102s, Vixen Ozuma, Zeiss Telementor II, , Goto Kogaku 65mm, Nippon Kogaku 65mm, etc
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