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Re: [tmboptical] Re: TMB 80mm "super" apo

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  • APM-Telescopes Markus Ludes
    Tom from where you have the technical specs you use for the Term super apo ? To my knowledge a superapo must have 4 crossings ( a normal apo 3 crossings) , and
    Message 1 of 27 , Apr 1, 2005
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      Tom

      from where you have the technical specs you use for the Term super apo ? To my knowledge a superapo must have 4 crossings ( a normal apo 3 crossings) , and nothing additional then other apos

      the 80 mm design exceed the APQ design and have 4 crossings and therefore LOMO called them with all rights super apo

      best wishes
      Markus
      ----- Original Message -----
      From: tmboptical
      To: tmboptical@yahoogroups.com
      Sent: Thursday, March 31, 2005 8:44 PM
      Subject: [tmboptical] Re: TMB 80mm "super" apo



      --- In tmboptical@yahoogroups.com, "APM-Telescopes Markus Ludes"
      <apm_telescopes@w...> wrote:
      >
      > Jack and Ron,
      >
      > The TMB designed 80mm f/6 fluorite apo is not a "Super Apo." It is
      > a little hyperbole on the part of LOMO. A super apochromat is a
      > lens with four zero color crossings, and is corrected for sphero-
      > chromatism at every zone on the aperture, in the visible spectrum,
      > and is corrected for coma.
      >
      > above is valid for the 80 mm Design

      I'm sorry Markus, and this is in no way putting down the fantastic
      performance of the TMB 80mm apos, but what you are saying is not
      true. When a lens design is corrected for spherochromatism at every
      zone on the aperture, it has no spherochromatism at all, or in
      other words, the Longitudinal Aberration for every wavelength from
      400nm to 700nm and beyond, will show straight lines, from the very
      center axis of the lens (0% zone), to the margin of the lens (100%
      zone).

      The only remaining aberration would be color, not spherical, and it
      would be how much chromatic focal shift each wavelength would have
      from each other, and that would mostly depend on how good the glass
      choices are, which in the case of all the TMB lenses, is about
      at the limits of minimum chromatic focal shift, because how well
      the partial dispersions of the three glasses match up.

      Thus, the LA graph you linked, would not look the way it does, it
      would have all the wavelengths straight on the graph, not curved
      like all lenses that have small air spaces or oil spaced lenses.

      Only lenses designed with at least one large air gap, and are
      aspherized, or have two higher order aspheres can achieve this
      degree of correction, i.e., a true Super Apochromatic.

      > No lens has ever been offered that meets
      > this optical quality definition.
      >
      > thats another thing. If we are 100% strictly, then you will also
      > find no triplet which show in strongest test 3 crossings, 1 is
      > always very very very little away

      Again, this is not correct for all triplet lenses. I can post the 3
      color crossings of the TMB 100mm f/8 lens, and it shows that from
      about 450nm to 750nm, the three zero point crossings are all well
      spaced from each other.

      Best Wishes,

      Thomas Back






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    • APM-Telescopes Markus Ludes
      ... From: Manoj Sood To: tmboptical@yahoogroups.com Sent: Friday, April 01, 2005 4:06 AM Subject: [tmboptical] TMB focusers I have a question re the new
      Message 2 of 27 , Apr 1, 2005
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        ----- Original Message -----
        From: Manoj Sood
        To: tmboptical@yahoogroups.com
        Sent: Friday, April 01, 2005 4:06 AM
        Subject: [tmboptical] TMB focusers



        I have a question re the new TMB/Starlight focusers now used on the new TMB
        scopes. I hear that they are rotatable and that the finder holder mounts
        onto the focuser?

        this is true for the 3.5" focuser versions only, not for the 2" focusers



        I assume this means that the finder can be rotated to a
        comfortable viewing position when the scope is in one of those awkward
        EQ-Mount induced positions?

        Can older TMB scopes be 'upgraded to this new rotatable focuser?

        you mean the old CNC ? you can upgrate that only with the 2" Starlight
        Markus

        Thanks
        Manoj








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      • tmboptical
        ... apo ? To my knowledge a superapo must have 4 crossings ( a normal apo 3 crossings) , and nothing additional then other apos ... therefore LOMO called them
        Message 3 of 27 , Apr 1, 2005
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          --- In tmboptical@yahoogroups.com, "APM-Telescopes Markus Ludes"
          <apm_telescopes@w...> wrote:
          > Tom
          >
          > from where you have the technical specs you use for the Term super
          apo ? To my knowledge a superapo must have 4 crossings ( a normal apo 3
          crossings) , and nothing additional then other apos
          >
          > the 80 mm design exceed the APQ design and have 4 crossings and
          therefore LOMO called them with all rights super apo
          >
          > best wishes
          > Markus

          Markus,

          From none other than the greatest optical scientist in the 20th century,
          and also the man that came up with the term "Super Apochromat," James
          G. Baker. In his groundbreaking article in Applied Optics, back in
          1963, called "Planetary Telescopes," he outlined why refractors are
          the very best telescopes of any type, for planetary observing, and
          in fact, showed back in the 1940's, that he was the inventor of the
          modern triplet apochromat, where the power element made out of CaF-2
          is in the center, and two crown elements were matched on the outside
          and inside of the triplet, just like TMB, AP, Zeiss, TAK, and TEC
          use today. His design would hold up to the best of today's designs,
          even know it was designed over 65 years ago. It was BK-7/CaF-2/K-10,
          a darn good true triplet apochromat.

          He also used the term Super Apochromat to describe an apochromat,
          that in his own words: "A Superapochromat is superachromatically
          corrected over the full aperture for aplanation."

          This means that for a lens to be a true Superapochromat, it must
          not only have four color crossings, but it must be aplanatic over
          the entire aperture (coma and spherical), which means no sphero-
          chromatism or coma. The reason no lens reaches this level of
          performance, and James Baker talks about this, is because you
          need to put two higher order aspherics on two surfaces of the
          lens, and this would no longer be a lens that could be sold
          in any real numbers, in fact, very few master opticians can
          do this type of figuring, and the costs would be extremely
          high per lens. So much so, no one would buy it.

          I recommend anyone that wants to learn more about the history of
          apo refractors, why apo refractors are as good as they are, the
          many different design types of apo refractors (for planetary use),
          what the requirements are for different levels of refractor
          correction, and what they mean, should either find a copy of his
          article at a University library, or download it off the Internet
          for about $15.00. It is the ultimate statement on why apo refractors
          are the best telescopes, inch for inch.

          Thomas Back
        • ronbee
          ... refractors ... Who can resist the master designer s such high recommendation ;-)! Here s the link if anyone is interested.
          Message 4 of 27 , Apr 1, 2005
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            --- In tmboptical@yahoogroups.com, "tmboptical" <TMBoptical@a...>
            wrote:
            > I recommend anyone that wants to learn more about the history of
            > apo refractors, why apo refractors are as good as they are, the
            > many different design types of apo refractors (for planetary use),
            > what the requirements are for different levels of refractor
            > correction, and what they mean, should either find a copy of his
            > article at a University library, or download it off the Internet
            > for about $15.00. It is the ultimate statement on why apo
            refractors
            > are the best telescopes, inch for inch.
            >
            > Thomas Back

            Who can resist the master designer's such high recommendation ;-)!
            Here's the link if anyone is interested.
            http://ao.osa.org/abstract.cfm?id=12990

            Beware that during the purchase if download fails, you'll have to
            call customer service (like I did :-(). So you may want to
            consider the email option, but beware also that the size of the PDF
            attachment is 2.6MB depending on your ISP (19 pages altogether).
            BTW, the customer service is great!

            Ron B[ee]
            PS - Thanks Thomas - I wonder what other goodies lurks in the
            Applied Optics ;-).
          • cjamescook
            Hey, thanks for the reference! (Maybe a section of the TMB FAQ could be devoted to a bibliography?) ... wrote:
            Message 5 of 27 , Apr 1, 2005
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              Hey, thanks for the reference!

              (Maybe a section of the TMB FAQ could be devoted to a bibliography?)

              --- In tmboptical@yahoogroups.com, "tmboptical" <TMBoptical@a...>
              wrote:
              ...
              > I recommend anyone that wants to learn more about the history of
              > apo refractors, why apo refractors are as good as they are, the
              > many different design types of apo refractors (for planetary use),
              > what the requirements are for different levels of refractor
              > correction, and what they mean, should either find a copy of his
              > article at a University library, or download it off the Internet
              > for about $15.00. It is the ultimate statement on why apo refractors
              > are the best telescopes, inch for inch.
              >
              > Thomas Back
            • Tube Tim
              ... Thanks for the informative post Thomas. Having the reference available (thanks Ron for that link!!! )behind the concepts allows the interested student of
              Message 6 of 27 , Apr 1, 2005
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                >--- In tmboptical@yahoogroups.com, "tmboptical" <TMBoptical@a...
                > From none other than the greatest optical scientist in the 20th
                > century, and also the man that came up with the term "Super
                > Apochromat," James G. Baker. In his groundbreaking article in
                > Applied Optics, back in 1963, called "Planetary Telescopes,"

                > snip <

                Thanks for the informative post Thomas. Having the reference available
                (thanks Ron for that link!!! )behind the concepts allows the
                interested student of optics to learn more. The TMB FAQ needs updated
                with the posts over the past 3 or so months, that's for sure.

                The bibliography on the TMB site, proposed by cJamesC is a good idea.

                ___
                Tim


                PS: I hope to make use of that 228 you sent me. The skies here at
                noon is so transparent here it's a beautiful pure blue. The downside
                is it's wind as all get out and seeing is in the tank. Clear Sky
                Clock (CSC) says seeing gets good around midnight just the same time
                the transparency goes to zero. Can't win! :-(

                Around 2:00 AM CSC says all is good, so I'll 'see' what happens.

                > Thomas Back
              • Jim Fusco
                Tom, correct me if im wrong there is no such word as a super apochromatic, It s superachromatic.
                Message 7 of 27 , Apr 1, 2005
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                  Tom, correct me if im wrong there is no such word as a super
                  apochromatic, It's superachromatic.

                  http://www.zeiss.de/C12567A8003B58B9/allBySubject/2D4B2DCF22C996C3C125
                  69BC005C33AF

                  Maybe the term super apo really means a extreamly well corrected APO?

                  The lens you and Dmitry Makolkin from SilverStar Optics that TMB
                  fully optimized was called a super-achromat, ED star manufacture. I
                  understand this is not a fully TMB designed lens, But TMB had a
                  significant input in the development of this lens to make this design
                  work. I was reading a old post by you that brings me to this. But
                  after reading the zeiss.de that a superachromat is a defect in a sort.
                  The design works on computer but changes in the manfacture process
                  keeps this the constant away and like 8 out of 10 lenses are very
                  well corrected APO and the 2 left over are SAPC or meet the
                  superachromatic requirements. Please correct me if my understanding
                  is wrong.


                  Best Regards,

                  Jim







                  --- In tmboptical@yahoogroups.com, "tmboptical" <TMBoptical@a...>
                  wrote:
                  >
                  > --- In tmboptical@yahoogroups.com, "APM-Telescopes Markus Ludes"
                  > <apm_telescopes@w...> wrote:
                  > > Tom
                  > >
                  > > from where you have the technical specs you use for the Term
                  super
                  > apo ? To my knowledge a superapo must have 4 crossings ( a normal
                  apo 3
                  > crossings) , and nothing additional then other apos
                  > >
                  > > the 80 mm design exceed the APQ design and have 4 crossings and
                  > therefore LOMO called them with all rights super apo
                  > >
                  > > best wishes
                  > > Markus
                  >
                  > Markus,
                  >
                  > From none other than the greatest optical scientist in the 20th
                  century,
                  > and also the man that came up with the term "Super Apochromat,"
                  James
                  > G. Baker. In his groundbreaking article in Applied Optics, back in
                  > 1963, called "Planetary Telescopes," he outlined why refractors are
                  > the very best telescopes of any type, for planetary observing, and
                  > in fact, showed back in the 1940's, that he was the inventor of the
                  > modern triplet apochromat, where the power element made out of CaF-2
                  > is in the center, and two crown elements were matched on the
                  outside
                  > and inside of the triplet, just like TMB, AP, Zeiss, TAK, and TEC
                  > use today. His design would hold up to the best of today's designs,
                  > even know it was designed over 65 years ago. It was BK-7/CaF-2/K-10,
                  > a darn good true triplet apochromat.
                  >
                  > He also used the term Super Apochromat to describe an apochromat,
                  > that in his own words: "A Superapochromat is superachromatically
                  > corrected over the full aperture for aplanation."
                  >
                  > This means that for a lens to be a true Superapochromat, it must
                  > not only have four color crossings, but it must be aplanatic over
                  > the entire aperture (coma and spherical), which means no sphero-
                  > chromatism or coma. The reason no lens reaches this level of
                  > performance, and James Baker talks about this, is because you
                  > need to put two higher order aspherics on two surfaces of the
                  > lens, and this would no longer be a lens that could be sold
                  > in any real numbers, in fact, very few master opticians can
                  > do this type of figuring, and the costs would be extremely
                  > high per lens. So much so, no one would buy it.
                  >
                  > I recommend anyone that wants to learn more about the history of
                  > apo refractors, why apo refractors are as good as they are, the
                  > many different design types of apo refractors (for planetary use),
                  > what the requirements are for different levels of refractor
                  > correction, and what they mean, should either find a copy of his
                  > article at a University library, or download it off the Internet
                  > for about $15.00. It is the ultimate statement on why apo refractors
                  > are the best telescopes, inch for inch.
                  >
                  > Thomas Back
                • APM-Telescopes Markus Ludes
                  Hi Tom, I know that what you write below, but in todays world it is to strict term, since if we follow strict terms, there shouldbe no one who call his apo,
                  Message 8 of 27 , Apr 2, 2005
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                    Hi Tom,

                    I know that what you write below, but in todays world it is to strict term, since if we follow strict terms, there shouldbe no one who call his apo, really apo , from design poinht maybe yes, but from making point no.

                    I mean if Zeiss take for themself the right to call here Binoculars super achromat, then LOMO shall have the same permission to call here 80 mm babys, Super - Apo , right ?

                    Takahashi, Vixen and others call here douplets Apo , doesnt matter if they say ED or Fluorite, this only indicates what type of glas they using, but this scopes should then not be called apos, right ?

                    so we have to allow Lomo the same flexibility to use terms as others have too

                    right or wrong ?

                    best wishes

                    Markus
                    ----- Original Message -----
                    From: tmboptical
                    To: tmboptical@yahoogroups.com
                    Sent: Friday, April 01, 2005 7:53 PM
                    Subject: [tmboptical] Re: TMB 80mm "super" apo



                    --- In tmboptical@yahoogroups.com, "APM-Telescopes Markus Ludes"
                    <apm_telescopes@w...> wrote:
                    > Tom
                    >
                    > from where you have the technical specs you use for the Term super
                    apo ? To my knowledge a superapo must have 4 crossings ( a normal apo 3
                    crossings) , and nothing additional then other apos
                    >
                    > the 80 mm design exceed the APQ design and have 4 crossings and
                    therefore LOMO called them with all rights super apo
                    >
                    > best wishes
                    > Markus

                    Markus,

                    >From none other than the greatest optical scientist in the 20th century,
                    and also the man that came up with the term "Super Apochromat," James
                    G. Baker. In his groundbreaking article in Applied Optics, back in
                    1963, called "Planetary Telescopes," he outlined why refractors are
                    the very best telescopes of any type, for planetary observing, and
                    in fact, showed back in the 1940's, that he was the inventor of the
                    modern triplet apochromat, where the power element made out of CaF-2
                    is in the center, and two crown elements were matched on the outside
                    and inside of the triplet, just like TMB, AP, Zeiss, TAK, and TEC
                    use today. His design would hold up to the best of today's designs,
                    even know it was designed over 65 years ago. It was BK-7/CaF-2/K-10,
                    a darn good true triplet apochromat.

                    He also used the term Super Apochromat to describe an apochromat,
                    that in his own words: "A Superapochromat is superachromatically
                    corrected over the full aperture for aplanation."

                    This means that for a lens to be a true Superapochromat, it must
                    not only have four color crossings, but it must be aplanatic over
                    the entire aperture (coma and spherical), which means no sphero-
                    chromatism or coma. The reason no lens reaches this level of
                    performance, and James Baker talks about this, is because you
                    need to put two higher order aspherics on two surfaces of the
                    lens, and this would no longer be a lens that could be sold
                    in any real numbers, in fact, very few master opticians can
                    do this type of figuring, and the costs would be extremely
                    high per lens. So much so, no one would buy it.

                    I recommend anyone that wants to learn more about the history of
                    apo refractors, why apo refractors are as good as they are, the
                    many different design types of apo refractors (for planetary use),
                    what the requirements are for different levels of refractor
                    correction, and what they mean, should either find a copy of his
                    article at a University library, or download it off the Internet
                    for about $15.00. It is the ultimate statement on why apo refractors
                    are the best telescopes, inch for inch.

                    Thomas Back






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                  • ericj
                    ... If you can make the changes to the FAQ and send it to me I ll get it uploaded to the site. ... Agreed, and I added a new bibliography page to the TMB site
                    Message 9 of 27 , Apr 2, 2005
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                      Hi Tim:

                      >Thanks for the informative post Thomas. Having the reference available
                      >(thanks Ron for that link!!! )behind the concepts allows the
                      >interested student of optics to learn more. The TMB FAQ needs updated
                      >with the posts over the past 3 or so months, that's for sure.

                      If you can make the changes to the FAQ and send it to me I'll get it
                      uploaded to the site.

                      >The bibliography on the TMB site, proposed by cJamesC is a good idea.

                      Agreed, and I added a new bibliography page to the TMB site which includes a
                      link to the article:

                      http://www.tmboptical.com/itemsGrid.asp?cat_id=50

                      If some kind soul who downloaded wishes to send it to me so it can be
                      uploaded to the site I'm make sure it gets up there, and I'm sure in
                      exchange Tom will give them a free TMB 10" apo ;-). Also let me know if
                      there are other links or articles that should be on the page and I'll add
                      them.

                      Thanks,

                      Eric Jamison
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