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Altair ULTRAFLAT Eyepiece

Discussion in 'Eyepieces, Barlows, and Filters' started by Mak the Night, Apr 3, 2019.

Altair ULTRAFLAT Eyepiece

Started by Mak the Night on Apr 3, 2019 at 4:16 AM

63 Replies 1476 Views 0 Likes

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  1. Mak the Night

    Mak the Night Well-Known Member

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  2. Mak the Night

    Mak the Night Well-Known Member

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  3. Gabby76

    Gabby76 Well-Known Member

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    Could be Kunming United Optical, they have a new line that is fairly close to these.
    Interesting though.

    I was just looking at the 15mm and the listed field stop measurement of 19.6mm is to large for a 65°AFOV eyepiece though. To achieve 19.6mm it would need a 75°AFOV?
     
  4. Mak the Night

    Mak the Night Well-Known Member

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    Have you got a link to the Kunming versions? I'll take your word for it on the field stop. Probably marketing exaggeration lol.
     
  5. Gabby76

    Gabby76 Well-Known Member

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    Just go to Kunming United Optical, they are the only eyepiece line showing at the moment.
    The bodies are slightly different and same for the focal lengths but that is really nothing new with the way they "tweak" numbers at times :)
     
  6. Mak the Night

    Mak the Night Well-Known Member

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  7. Gabby76

    Gabby76 Well-Known Member

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    They could be, hard to tell at times as some retailers get them with different barrels, change a number 1-2mm to "make it their own" and other such things.

    The worst exageration I have found is one companies 50mm 70°AFOV eyepiece. When you actually measure it the AFOV is only 43°!
     
  8. Mak the Night

    Mak the Night Well-Known Member

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  9. Gabby76

    Gabby76 Well-Known Member

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    I really, really hate everyone calling their eyepieces "Plossl" when they are clearly not!
    No such thing as a 70°AFOV Plossl. Most likely a Erfle or Konig...
    There has only been one company that has made a true Plossl eyepiece since Clave stopped making them and that was Long Perng in the mid 2000s and they only made one production run of them.
    I managed to get two 23mm for binoviewing.
     
  10. Mak the Night

    Mak the Night Well-Known Member

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    Plossl is essentially a marketing term now.
     
  11. Leonard

    Leonard Well-Known Member

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  12. Leonard

    Leonard Well-Known Member

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    That is certainly true. I think a plossl is actually the proper label of 3 types of eyepiece configuration.

    1) The original Clave design introduced in 1955. It started with asymmetric doublets = four unique lenses cemented together into two different size doublets.

    2) The present day plossl consisting of two symmetrical doublets. The majority of Plossls are of this design. It is the easiest and most cost efficient to manufacture as it requires only two unique glass elements. The results are a fine eyepiece when properly manufactured.

    3) The Tele Vue improvement: introduced in 1980, high index glass configured into symmetrical doublets where the outer lens of the doublets are double concave. Including TV, Meade Series 4000, and Sterling Optical and a few others use this advanced design. It produces outstanding EPs, but is more difficult to make.

    In my opinion, others are purposely mislabeled.
     
  13. Mak the Night

    Mak the Night Well-Known Member

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    I'm pretty sure you're right about this. I don't even think the Austrian Simon Plössl (1794 ~ 1868) had telescopes in mind when he designed the eyepiece he is famous for.

    http://www.simon-plossl.com/

    Plus, they were originally expensive and highly valued which added to their mystique. I've been to Austria, they drive on the wrong side of the road and drink lager. Although hopefully not at the same time.
     
  14. Gabby76

    Gabby76 Well-Known Member

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    The Clave design is the same as that patented in 1938 by Zeiss, very good eyepieces but still not "true" Plossl in comparison to the design from G.S. Plossl though both are asymmetrical and use 3 different glass types.
    (The Clave 0.965" eyepieces were a bit better than the 1.25")
    You are right Mak, most of Plossl work was for microscopes, opera glasses and camera lens.

    None of the Plossl varieties has unique glass in them, quite standard crown and flints. They do require a fair bit of precision to make though not as much as a Abbe design.

    Other than marketing even Mr. Nagler did not call his eyepieces Plossl when filing for patent, he called them Symmetrical with Plossl like characteristics.
     
  15. Mak the Night

    Mak the Night Well-Known Member

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    'Symmetrical with Plossl like characteristics' is too long for most housings though. ;)
     
  16. Gabby76

    Gabby76 Well-Known Member

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    Just Mr. Nagler riding the end of the Clave Plossl hype
    Easier at the time to sell Plossl than Symmetrical I imagine.

    I prefer more neutral views in the eyepiece so tend not to use the TeleVue Plossl much, the only one I currently have is a 11mm and it is looking like it is going to be pushed out of the way by a Siebert Optics 11mm Performance+ :)


    Everytime I look at that Altair image I am reminded of the Orion Stratus eyepiece line...
     
  17. Mak the Night

    Mak the Night Well-Known Member

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    I have all the TV Plossls. I've even used some of them. I've just ordered a 12mm Meade 5000 HD-60. I have a new 12mm X-Cel and as I couldn't decide between the two I've decided on both. It's rumoured they have the same glass anyway. Meade often refer to them as Plossls lol. I'm about to pull the trigger on the 15mm Altair. Even if it does have safety barfs.
     
  18. Gabby76

    Gabby76 Well-Known Member

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    Just Mr. Nagler riding the end of the Clave Plossl hype
    Easier at the time to sell Plossl than Symetrical I imagine.
     
  19. Mak the Night

    Mak the Night Well-Known Member

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    Deja vu all over again.
     
  20. Mak the Night

    Mak the Night Well-Known Member

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