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Re: [tmboptical] TMB 100/800 CNC Classic

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  • david albritton
    Hi Wayne, I remember reading an article by Thomas Back. He stated that his personal 100/800 had a strehl of .997 (which is supposedly the highest strehl LZOS
    Message 1 of 11 , Jun 1, 2008
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      Hi Wayne,
      I remember reading an article by Thomas Back. He stated that his personal 100/800 had a strehl of .997 (which is supposedly the highest strehl LZOS lense). He also stated that his Astro-physics 180mm f/9 EDT had a strehl of .9975. Roland Christen gave him a copy of the report. That's probably as perfect as your gonna get. I was surprised to find the strehl report for my 100/800 lightweight shows a .993. I don't know much about what the numbers mean other than this would be a highly corrected lense. Can't wait to view through it.

      Wayne G <fomalhaut@...> wrote:
      izar21093 wrote:
      > Other than myself, is any one still using the 4" f-8 scoope on a
      > regular basis? Mine has become my main visual scope and always delivers
      > an excellent performance.
      >

      WG: Bill, I would certainly hope so, as the 4" Apo is perhaps the most
      common, popular and favored sizes of all Apos out there and the 100/800
      CNC was touted by Tom himself (who kept one in his personal collection
      with a strehl around .99 I believe) as perhaps the very pinnacle of all
      the lenses he ever designed through LZOS.

      If I ever buy another APM/TMB it would most likely be this one, in the
      classic CNC tube of course--- perhaps the best 4" apochromat ever made IMO.

      WayneG







      [Non-text portions of this message have been removed]
    • david albritton
      Hi Bill, Thanks for the info. My plans are to use this scope as a kinda grab and go scope w/ a quick set-up time. I was planning on purchasing a non-goto G-8
      Message 2 of 11 , Jun 1, 2008
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        Hi Bill,
        Thanks for the info. My plans are to use this scope as a kinda grab and go scope w/ a quick set-up time. I was planning on purchasing a non-goto G-8 and use a Kendrick power pack. This is all very new to me. I'll be green for some time but I have researched a lot of products on the market and have read a lot of reviews. I am still learning a lot. I'm not at all familiar with the Argo Navis or Sky Commander programs or even how to go about using one, for that matter. I know nothing about digital setting circles, either. I would appreciate any advice and recommendations on setting this scope up. You might have to explain some things in laymens terms until I understand some of the lingo.
        Thanks, David

        izar21093 <izar21093@...> wrote:
        I'm sure you will not be disappointed. I have not used one of the
        LW's but I believe the optics are the same as mine. I have pushed it
        to 400x under very good skies and believe it could go beyond 400x
        with better skies.

        Most of my use is visual but I have done a bit of double-star
        measurement to compare with measurements made with my six inch
        reflector years ago.

        These scopes are a joy to use. With the G-8 I highly recommend the
        Argo Navis for pointing. The AN complements the TMB quality extremely
        well. The combination of great mount, scope and computer make every
        night out pleasureable.

        Bill G

        --- In tmboptical@yahoogroups.com, david albritton <mator5872@...>
        wrote:
        >
        > Hi Bill,
        > I have a lightweight 4" f-8 but have yet had a chance to view
        through it. I am very pleased with the quality of the OTA. The
        FeatherTouch focuser is awesome. I am currently saving to get a
        Losmandy G-8. This is my first scope purchase so I am pretty excited.
        Can't wait to view through it.
        >
        > izar21093 <izar21093@...> wrote:
        > Other than myself, is any one still using the 4" f-8
        scoope on a
        > regular basis? Mine has become my main visual scope and always
        delivers
        > an excellent performance.
        >
        > It is mounted on a well maintained CI-700 GEM with an Argo Navis
        for
        > pointing under my bright urban sky. The FeatherTouch focuser is
        superb.
        >
        > The scope (AKA: "Fancy Pants") is still as pictured in the photo
        > section.
        >
        > Bill G
        >
        >
        >
        >
        >
        >
        >
        > [Non-text portions of this message have been removed]
        >







        [Non-text portions of this message have been removed]
      • Wayne G
        ... WG: As do I, Bill, as I believe more so than any other product he ever made or designed since, the real heart and soul of Thomas lives on in these
        Message 3 of 11 , Jun 1, 2008
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          izar21093 wrote:
          > Wayne,
          >
          > <snip> I hope others have not sidelined these scopes.
          >
          > Bill G
          >

          WG: As do I, Bill, as I believe more so than any other product he ever
          made or designed since, the real heart and soul of Thomas lives on in
          these original design refractors--- these were what Thomas envisioned
          he wanted in a telescope, these were his dream--- what he put forth to
          the world to exclaim: "Here I Am!"; this is what he came up with
          starting from a clean slate where anything was possible and all options
          were on the table to achieve his 'ultimate' apochromat.

          WayneG
        • Wayne G
          ... WG: A theoretically perfect lens would have a strehl ratio of 1.0. In practice though, anything at or above .95 is sensibly perfect and considered a
          Message 4 of 11 , Jun 1, 2008
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            david albritton wrote:
            > I don't know much about what the numbers mean other than this would be a highly corrected lense. Can't wait to view through it.
            >

            WG: A theoretically perfect lens would have a strehl ratio of 1.0. In
            practice though, anything at or above .95 is sensibly "perfect" and
            considered a 'planetary telescope.' The strehl number (easier for
            people to relate to than rms) is derived from the r.m.s. value and
            relates to how well the optic focuses all light from a point source to
            be kept within the diffraction disc.

            A perfect lens would focus 100% of all light within the diffraction
            disc. A scope of .98 strehl focuses 98% of all available light to where
            it should go.

            But when you get to numbers as high as some you mentioned, I begin to
            wonder about how the tests were done--- I do not believe any test is
            sensitive enough to accurately determine a strehl of .9975, and it
            really doesn't make any difference in use over the images given by a
            scope of .9875--- in focus, you won't see any difference at all and
            only the truly gifted star tester has a chance of seeing the difference
            out of focus (where no scope operates anyway).

            Once you get beyond .95, you are "there" and all lenses made by LZOS are
            guaranteed to be this good or better.

            WayneG
          • izar21093
            Sounds good David. Don t bother with digital setting circles until you need them or feel ready for them. Learn the sky first and have fun. I taught my kids to
            Message 5 of 11 , Jun 1, 2008
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              Sounds good David.

              Don't bother with digital setting circles until you need them or feel
              ready for them. Learn the sky first and have fun. I taught my kids to
              drive a standard shift before letting them use an automatic.

              I use a jump start battery to power the mount when away from home. At
              home I use a 12v power supply. Very basic.

              Enjoy.

              Bill G


              --- In tmboptical@yahoogroups.com, david albritton <mator5872@...>
              wrote:
              >
              > Hi Bill,
              > Thanks for the info. My plans are to use this scope as a kinda
              grab and go scope w/ a quick set-up time. I was planning on
              purchasing a non-goto G-8 and use a Kendrick power pack. This is all
              very new to me. I'll be green for some time but I have researched a
              lot of products on the market and have read a lot of reviews. I am
              still learning a lot. I'm not at all familiar with the Argo Navis or
              Sky Commander programs or even how to go about using one, for that
              matter. I know nothing about digital setting circles, either. I
              would appreciate any advice and recommendations on setting this scope
              up. You might have to explain some things in laymens terms until I
              understand some of the lingo.
              > Thanks, David
              >
              > izar21093 <izar21093@...> wrote:
              > I'm sure you will not be disappointed. I have not used
              one of the
              > LW's but I believe the optics are the same as mine. I have pushed
              it
              > to 400x under very good skies and believe it could go beyond 400x
              > with better skies.
              >
              > Most of my use is visual but I have done a bit of double-star
              > measurement to compare with measurements made with my six inch
              > reflector years ago.
              >
              > These scopes are a joy to use. With the G-8 I highly recommend the
              > Argo Navis for pointing. The AN complements the TMB quality
              extremely
              > well. The combination of great mount, scope and computer make every
              > night out pleasureable.
              >
              > Bill G
              >
              > --- In tmboptical@yahoogroups.com, david albritton <mator5872@>
              > wrote:
              > >
              > > Hi Bill,
              > > I have a lightweight 4" f-8 but have yet had a chance to view
              > through it. I am very pleased with the quality of the OTA. The
              > FeatherTouch focuser is awesome. I am currently saving to get a
              > Losmandy G-8. This is my first scope purchase so I am pretty
              excited.
              > Can't wait to view through it.
              > >
              > > izar21093 <izar21093@> wrote:
              > > Other than myself, is any one still using the 4" f-8
              > scoope on a
              > > regular basis? Mine has become my main visual scope and always
              > delivers
              > > an excellent performance.
              > >
              > > It is mounted on a well maintained CI-700 GEM with an Argo Navis
              > for
              > > pointing under my bright urban sky. The FeatherTouch focuser is
              > superb.
              > >
              > > The scope (AKA: "Fancy Pants") is still as pictured in the photo
              > > section.
              > >
              > > Bill G
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > > [Non-text portions of this message have been removed]
              > >
              >
              >
              >
              >
              >
              >
              >
              > [Non-text portions of this message have been removed]
              >
            • izar21093
              Roger that !! ... ever ... in ... envisioned ... forth to ... options
              Message 6 of 11 , Jun 1, 2008
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                Roger that !!



                --- In tmboptical@yahoogroups.com, Wayne G <fomalhaut@...> wrote:
                >
                > izar21093 wrote:
                > > Wayne,
                > >
                > > <snip> I hope others have not sidelined these scopes.
                > >
                > > Bill G
                > >
                >
                > WG: As do I, Bill, as I believe more so than any other product he
                ever
                > made or designed since, the real heart and soul of Thomas lives on
                in
                > these original design refractors--- these were what Thomas
                envisioned
                > he wanted in a telescope, these were his dream--- what he put
                forth to
                > the world to exclaim: "Here I Am!"; this is what he came up with
                > starting from a clean slate where anything was possible and all
                options
                > were on the table to achieve his 'ultimate' apochromat.
                >
                > WayneG
                >
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