Loading ...
Sorry, an error occurred while loading the content.

difference between ED, SD, fluorite

Expand Messages
  • michelderomme
    Hi all I asked a question a few days ago about differences between ED, SD fluorite... Tom trusock answered me but I m unable to find his answer on my computer.
    Message 1 of 6 , Jan 4, 2006
    • 0 Attachment
      Hi all
      I asked a question a few days ago about differences between ED, SD
      fluorite...
      Tom trusock answered me but I'm unable to find his answer on my
      computer.
      anybody can help me please ?
      thanks
      Michel
    • Timm Bottoni
      Hi, I think this might be the post.... http://groups.yahoo.com/group/William-Optics/message/6532 Hope it helps, Timm
      Message 2 of 6 , Jan 4, 2006
      • 0 Attachment
        Hi,

        I think this might be the post....
        http://groups.yahoo.com/group/William-Optics/message/6532

        Hope it helps,

        Timm

        --- In William-Optics@yahoogroups.com, "michelderomme"
        <michel.deromme@f...> wrote:
        >
        > Hi all
        > I asked a question a few days ago about differences between ED, SD
        > fluorite...
        > Tom trusock answered me but I'm unable to find his answer on my
        > computer.
        > anybody can help me please ?
        > thanks
        > Michel
        >
      • michelderomme
        Thanks Timm, that s what I was looking for Michel ... SD
        Message 3 of 6 , Jan 4, 2006
        • 0 Attachment
          Thanks Timm, that's what I was looking for
          Michel


          --- In William-Optics@yahoogroups.com, "Timm Bottoni"
          <t.bottoni@c...> wrote:
          >
          > Hi,
          >
          > I think this might be the post....
          > http://groups.yahoo.com/group/William-Optics/message/6532
          >
          > Hope it helps,
          >
          > Timm
          >
          > --- In William-Optics@yahoogroups.com, "michelderomme"
          > <michel.deromme@f...> wrote:
          > >
          > > Hi all
          > > I asked a question a few days ago about differences between ED,
          SD
          > > fluorite...
          > > Tom trusock answered me but I'm unable to find his answer on my
          > > computer.
          > > anybody can help me please ?
          > > thanks
          > > Michel
          > >
          >
        • Tom Trusock
          ... Here it is again sir: Hi Michel, There have already been some wonderful comments in this thread - if you read back, they will probably go a long way
          Message 4 of 6 , Jan 4, 2006
          • 0 Attachment
            --- In William-Optics@yahoogroups.com, "michelderomme"
            <michel.deromme@f...> wrote:
            >
            > Hi all
            > I asked a question a few days ago about differences between ED, SD
            > fluorite...
            > Tom trusock answered me but I'm unable to find his answer on my
            > computer.
            > anybody can help me please ?
            > thanks
            > Michel
            >


            Here it is again sir:

            Hi Michel,

            There have already been some wonderful comments in this thread - if
            you read back, they will probably go a long way towards answering
            some if not all of your questions, but I'll throw in my .02 cents
            here as well.

            ED and SD are generally considered to be two different names for the
            same family of glasses. I think it was Nikon coined the term ED -
            prompting Canon to counter with SD. Both were marketing terms that
            described glasses with extra, special or supra dispersion properties
            as measured by their abbe number. ED is more typically used today,
            but there's nothing inherently incorrect about SD.

            ED/SD glasses can cover a wide range, but for today's astronomical
            applications usually consist of glasses with similar properties to
            those found in Ohara's catalog under the designations s-fpl51, s-
            fpl52 and s-fpl53 (more often referred to as FPL51, 52 and 53). For
            the record, from it's abbe number there is minimal diffference
            between fluorite and fpl53. I've been given to understand that pure
            fluorite does have a small advantage in that it has a slightly
            higher transmission and lower scatter in certain wavelengths than
            fpl-53, but the advantages are mainly photographic, and not all that
            great. Equally important to the choice of the ED/SD glass is the
            choice of a good mate.

            Everyone talks about color correction, but the sheer fact of the
            matter is there really are other things that are just if not more
            important depending on the application you have in mind. I suspect
            everyone picks on color correction because it's easy to see.

            In any case, the design of the lens and the glasses used are
            paramount in determining correction, however, many other factors
            come into play as well. Typically the best doublets are not as well
            corrected as the best corrected triplets - however, doublets are
            lighter, cool down faster, and have a few other advantages as well
            (largely to the visual observer). Triplets, OTOH, are generally
            preferred for photographic applications.

            As I see it, the major difference between the ZenithStar and Megrez
            family have more to do with the OTA than the lenses. Outside of the
            FLT-100 (which is a different beast entirely) the Megrez scopes are
            white with a painted or powercoated finish, and use a foam baffle
            system. They have a more traditional look to them. The Zenithstars
            tend to be anodized and use a cone baffle system. The anodizing
            looks extremely sharp, but has a single drawback - it picks up
            fingerprints like crazy.

            I've seen samples of both lines, and both do their job well. Which
            you prefer is entirely up to you.

            As per the 66 doublet / triplet / petzval discussion - well, as a
            visual observer, I tend to prefer doublets. In general, a good
            ED/SD doublet is smaller, lighter (and thus easier to mount), and
            still offers acceptable color correction. I haven't seen the 66 SD
            doublet yet, but I'm lucky enough to have the fluorite version (a
            very limited production). Assuming the SD version performs like the
            fluorite version, I'd recommend the SD doublet for the visual
            observer. The triplet generally offers better color correction for
            those who are really picky about that or who are photographers.
            Petzvals are an excellent choice for someone who is on a slightly
            more restriced budget. The petzval gives about 30-35% less false
            color than a similar size achro simply due to it's design. While I
            wouldn't recommend it for typical photography due to it's color
            correction, it would do very well for narrow band applications.

            Hope something here helps.

            Tom T.
          • Tom Trusock
            ... SD ... Opps - beat me to it. Thanks Timm T
            Message 5 of 6 , Jan 4, 2006
            • 0 Attachment
              --- In William-Optics@yahoogroups.com, "Timm Bottoni"
              <t.bottoni@c...> wrote:
              >
              > Hi,
              >
              > I think this might be the post....
              > http://groups.yahoo.com/group/William-Optics/message/6532
              >
              > Hope it helps,
              >
              > Timm
              >
              > --- In William-Optics@yahoogroups.com, "michelderomme"
              > <michel.deromme@f...> wrote:
              > >
              > > Hi all
              > > I asked a question a few days ago about differences between ED,
              SD
              > > fluorite...
              > > Tom trusock answered me but I'm unable to find his answer on my
              > > computer.
              > > anybody can help me please ?
              > > thanks
              > > Michel
              > >
              >


              Opps - beat me to it.

              Thanks Timm

              T
            • michelderomme
              Tom Thanks a lot, here we are talking about WO http://www.astrosurf.com/ubb/Forum2/HTML/016357-2.html Michel ... SD ... the ... properties ... that
              Message 6 of 6 , Jan 5, 2006
              • 0 Attachment
                Tom
                Thanks a lot, here we are talking about WO
                http://www.astrosurf.com/ubb/Forum2/HTML/016357-2.html
                Michel

                --- In William-Optics@yahoogroups.com, "Tom Trusock" <tomt@c...>
                wrote:
                >
                > --- In William-Optics@yahoogroups.com, "michelderomme"
                > <michel.deromme@f...> wrote:
                > >
                > > Hi all
                > > I asked a question a few days ago about differences between ED,
                SD
                > > fluorite...
                > > Tom trusock answered me but I'm unable to find his answer on my
                > > computer.
                > > anybody can help me please ?
                > > thanks
                > > Michel
                > >
                >
                >
                > Here it is again sir:
                >
                > Hi Michel,
                >
                > There have already been some wonderful comments in this thread - if
                > you read back, they will probably go a long way towards answering
                > some if not all of your questions, but I'll throw in my .02 cents
                > here as well.
                >
                > ED and SD are generally considered to be two different names for
                the
                > same family of glasses. I think it was Nikon coined the term ED -
                > prompting Canon to counter with SD. Both were marketing terms that
                > described glasses with extra, special or supra dispersion
                properties
                > as measured by their abbe number. ED is more typically used today,
                > but there's nothing inherently incorrect about SD.
                >
                > ED/SD glasses can cover a wide range, but for today's astronomical
                > applications usually consist of glasses with similar properties to
                > those found in Ohara's catalog under the designations s-fpl51, s-
                > fpl52 and s-fpl53 (more often referred to as FPL51, 52 and 53). For
                > the record, from it's abbe number there is minimal diffference
                > between fluorite and fpl53. I've been given to understand that pure
                > fluorite does have a small advantage in that it has a slightly
                > higher transmission and lower scatter in certain wavelengths than
                > fpl-53, but the advantages are mainly photographic, and not all
                that
                > great. Equally important to the choice of the ED/SD glass is the
                > choice of a good mate.
                >
                > Everyone talks about color correction, but the sheer fact of the
                > matter is there really are other things that are just if not more
                > important depending on the application you have in mind. I suspect
                > everyone picks on color correction because it's easy to see.
                >
                > In any case, the design of the lens and the glasses used are
                > paramount in determining correction, however, many other factors
                > come into play as well. Typically the best doublets are not as well
                > corrected as the best corrected triplets - however, doublets are
                > lighter, cool down faster, and have a few other advantages as well
                > (largely to the visual observer). Triplets, OTOH, are generally
                > preferred for photographic applications.
                >
                > As I see it, the major difference between the ZenithStar and Megrez
                > family have more to do with the OTA than the lenses. Outside of the
                > FLT-100 (which is a different beast entirely) the Megrez scopes are
                > white with a painted or powercoated finish, and use a foam baffle
                > system. They have a more traditional look to them. The Zenithstars
                > tend to be anodized and use a cone baffle system. The anodizing
                > looks extremely sharp, but has a single drawback - it picks up
                > fingerprints like crazy.
                >
                > I've seen samples of both lines, and both do their job well. Which
                > you prefer is entirely up to you.
                >
                > As per the 66 doublet / triplet / petzval discussion - well, as a
                > visual observer, I tend to prefer doublets. In general, a good
                > ED/SD doublet is smaller, lighter (and thus easier to mount), and
                > still offers acceptable color correction. I haven't seen the 66 SD
                > doublet yet, but I'm lucky enough to have the fluorite version (a
                > very limited production). Assuming the SD version performs like the
                > fluorite version, I'd recommend the SD doublet for the visual
                > observer. The triplet generally offers better color correction for
                > those who are really picky about that or who are photographers.
                > Petzvals are an excellent choice for someone who is on a slightly
                > more restriced budget. The petzval gives about 30-35% less false
                > color than a similar size achro simply due to it's design. While I
                > wouldn't recommend it for typical photography due to it's color
                > correction, it would do very well for narrow band applications.
                >
                > Hope something here helps.
                >
                > Tom T.
                >
              Your message has been successfully submitted and would be delivered to recipients shortly.