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Re: Mewlon or Dob?

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  • mark_1968
    ... their ability to make fine telescopes ... is of no disadvantage, if you add proper ventilation, ... Hi Heinz, Interesting post! Thanks for sharing your
    Message 1 of 28 , Jan 1, 2008
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      --- In UncensoredTakGroup@yahoogroups.com, Heinz Künzli
      <apus.tak@...> wrote:
      >
      > Hi Greg, group
      ><snipped>
      >
      > In the case of the Mewlons, I think that Takahashi is wasting
      their ability to make fine telescopes
      > with the wrong optical design.
      > They should make Maksutows, instead of Dall-Kirkhams!
      > The added weight of a corrector is worth it, and the closed design
      is of no disadvantage, if you add proper ventilation,
      > as I did in the Intes Maksutow. Cooling down is no problem.
      >
      > <snip>
      > Heinz
      >

      Hi Heinz,

      Interesting post! Thanks for sharing your many experiences.

      Yes, what if Tak made Maksutovs? I am surprised that Tak has not
      pushed themselves more, given that they are a top-tier telescope
      maker. Although every design is a balance of compromises, I would
      think that Tak could have been more tilted towards the best
      performance possible.

      Mark
    • Roberto Abraham
      Hi Heinz, ... I agree it s something of a special purpose telescope, since of course the diffraction-limited field of view of an f/12 Dall-Kirkham design with
      Message 2 of 28 , Jan 1, 2008
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        Hi Heinz,

        --- In UncensoredTakGroup@yahoogroups.com, Heinz Künzli <apus.tak@...> wrote:
        >
        > There are general purpose telescopes and special purpose telescopes.
        > The Mewlon clearly is a special purpose telescope.
        > I would recommend it only as a second or third telescope,
        > if, and only if,
        > - you have very good seeing AND want to use it with high magnifications
        > - OR only use it near the optical axis (spectroscopy)
        > - or do not bother about aberrations.

        I agree it's something of a special purpose telescope, since of
        course the diffraction-limited field of view of an f/12 Dall-Kirkham
        design with an f/3 primary mirror is relatively small. BUT, what a great view
        on-axis! And the Mewlon is very light and easy to mount, cools down
        more quickly than my closed-tube Maks, and the scope is
        quite immune to dew and frost.

        All telescope designs are are trade-offs. As you know some are
        better suited as single 'general purpose' instruments than others. To
        reinforce your basic point, I also wouldn't recommend a Mewlon
        as the sole instrument for anybody whose main interest was not
        in the direction of planets and double stars.

        But, accepting that, I find the Mewlon to be a very attractive design.
        It's a wonderfully high-quality, easily deployable, conveniently portable
        high-magnification telescope. I really enjoy mine (a Mewlon 180).
        I also own a TEC MC200 8" Mak, which I also enjoy, and which
        outperforms my Mewlon 180. However, the big Mak is a much bigger
        hassle to set up and move around and takes longer to cool down,
        and I seem to spend all my time with both telescopes looking on-axis
        anyway, so optimizing for that (as the Mewlon does) makes a lot of
        sense to me. The views through the Mewlon are quite sublime.

        Overall, I find the Mewlon 180 to be a terrific telescope. However,
        I've also been quite surprised by some of the really 'gushing' reviews
        on the internet that almost seem to suggest that a Mewlon is
        the apex of telescope design in all areas. I wish these were a little
        more critical and a bit more balanced. On the
        other hand, I do think that owning a smallish APO refractor,
        a mid-aperture Mewlon, and a big dob would be an excellent
        combination for many/most people.

        Regards,

        Roberto
      • EDUARDO LÓPEZ
        i need the reducer aplanant for the FS-78, send me a e-mail to edulopez0000@yahoo.es
        Message 3 of 28 , Jan 2, 2008
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          i need the reducer aplanant for the FS-78, send me a e-mail to
          edulopez0000@...
        • andyrobertson100
          Hi Greg, Only just read this thread. I own a Mewlon 300 and live in the UK. A couple of years ago at a specific request I resonded to a forum in the UK on
          Message 4 of 28 , Jan 2, 2008
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            Hi Greg,

            Only just read this thread. I own a Mewlon 300 and live in the UK. A
            couple of years ago at a specific request I resonded to a forum in the
            UK on Apo's v Mewlons by posting my experiences. I've reproduced it in
            the 'Files' section of this group. May be of interest to you.

            Andy Robertson.
          • Greg Tober
            Hello again Group! Thanks for all the great Mewlon information on this thread; it s much appreciated. It s kind of off-topic, but I thought Heinz s and Mark s
            Message 5 of 28 , Jan 3, 2008
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              Hello again Group! Thanks for all the great Mewlon information on this thread; it's much
              appreciated.

              It's kind of off-topic, but I thought Heinz's and Mark's reference to Maksutovs was
              interesting. My very first telescope, before about a 20 year hiatus from the hobby, was a
              C90. I remember it being a great little scope. Other than very long cool-down and
              stabilization times, I know they are generally regarded for excellent image quality across
              the entire field. I know TEC used to produce these, and now ITE seems to have a corner on
              the Mak market. Anyone have any experiences with 7" or larger Mak-Cas or Mak-Newts?

              Thanks again for all the great responses. It's groups like this that make researching for
              that next scope almost as fun as actually observing through it.

              Greg T

              --- In UncensoredTakGroup@yahoogroups.com, "mark_1968" <mark_1968@...> wrote:
              >
              > --- In UncensoredTakGroup@yahoogroups.com, Heinz Künzli
              > <apus.tak@> wrote:
              > >
              > > Hi Greg, group
              > ><snipped>
              > >
              > > In the case of the Mewlons, I think that Takahashi is wasting
              > their ability to make fine telescopes
              > > with the wrong optical design.
              > > They should make Maksutows, instead of Dall-Kirkhams!
              > > The added weight of a corrector is worth it, and the closed design
              > is of no disadvantage, if you add proper ventilation,
              > > as I did in the Intes Maksutow. Cooling down is no problem.
              > >
              > > <snip>
              > > Heinz
              > >
              >
              > Hi Heinz,
              >
              > Interesting post! Thanks for sharing your many experiences.
              >
              > Yes, what if Tak made Maksutovs? I am surprised that Tak has not
              > pushed themselves more, given that they are a top-tier telescope
              > maker. Although every design is a balance of compromises, I would
              > think that Tak could have been more tilted towards the best
              > performance possible.
              >
              > Mark
              >
            • mark_1968
              ... this thread; it s much ... to Maksutovs was ... hiatus from the hobby, was a ... long cool-down and ... excellent image quality across ... seems to have a
              Message 6 of 28 , Jan 3, 2008
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                --- In UncensoredTakGroup@yahoogroups.com, "Greg Tober"
                <gtober6708@...> wrote:
                >
                > Hello again Group! Thanks for all the great Mewlon information on
                this thread; it's much
                > appreciated.
                >
                > It's kind of off-topic, but I thought Heinz's and Mark's reference
                to Maksutovs was
                > interesting. My very first telescope, before about a 20 year
                hiatus from the hobby, was a
                > C90. I remember it being a great little scope. Other than very
                long cool-down and
                > stabilization times, I know they are generally regarded for
                excellent image quality across
                > the entire field. I know TEC used to produce these, and now ITE
                seems to have a corner on
                > the Mak market. Anyone have any experiences with 7" or larger Mak-
                Cas or Mak-Newts?
                >
                > Thanks again for all the great responses. It's groups like this
                that make researching for
                > that next scope almost as fun as actually observing through it.
                >
                > Greg T
                >

                Hi Greg,

                Occasionally I think about going the Mak-Cass or Mak-Newt route but
                from what I can gather, the number of makers is quite small: Intes-
                Micro, Santel, STF, AP/ARIES, etc. ITE, by the way, is only a
                retailer and one of several that carry Maks. I'm planning on
                waiting until there are more choices and this type of design is
                refined further - I'm not sure anyone except Astro-physics has a
                good handle on how to cool down these designs rapidly. Until then,
                a Mewlon could make a fine choice :)

                Yes, it's fun to decide!

                Mark
              • andyrobertson100
                Hi Greg, Did you read the article I posted in the articles section 2 days ago, Apo Refractor-Reflector-Mewlon ? I discussed Mak-Newts in that article.
                Message 7 of 28 , Jan 4, 2008
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                  Hi Greg,

                  Did you read the article I posted in the articles section 2 days
                  ago, " Apo Refractor-Reflector-Mewlon"? I discussed Mak-Newts in
                  that article.

                  Andrew.

                  --- In UncensoredTakGroup@yahoogroups.com, "Greg Tober"
                  <gtober6708@...> wrote:
                  >
                  > Hello again Group! Thanks for all the great Mewlon information on
                  this thread; it's much
                  > appreciated.
                  >
                  > It's kind of off-topic, but I thought Heinz's and Mark's reference
                  to Maksutovs was
                  > interesting. My very first telescope, before about a 20 year
                  hiatus from the hobby, was a
                  > C90. I remember it being a great little scope. Other than very
                  long cool-down and
                  > stabilization times, I know they are generally regarded for
                  excellent image quality across
                  > the entire field. I know TEC used to produce these, and now ITE
                  seems to have a corner on
                  > the Mak market. Anyone have any experiences with 7" or larger Mak-
                  Cas or Mak-Newts?
                  >
                  > Thanks again for all the great responses. It's groups like this
                  that make researching for
                  > that next scope almost as fun as actually observing through it.
                  >
                  > Greg T
                  >
                  > --- In UncensoredTakGroup@yahoogroups.com, "mark_1968"
                  <mark_1968@> wrote:
                  > >
                  > > --- In UncensoredTakGroup@yahoogroups.com, Heinz Künzli
                  > > <apus.tak@> wrote:
                  > > >
                  > > > Hi Greg, group
                  > > ><snipped>
                  > > >
                  > > > In the case of the Mewlons, I think that Takahashi is wasting
                  > > their ability to make fine telescopes
                  > > > with the wrong optical design.
                  > > > They should make Maksutows, instead of Dall-Kirkhams!
                  > > > The added weight of a corrector is worth it, and the closed
                  design
                  > > is of no disadvantage, if you add proper ventilation,
                  > > > as I did in the Intes Maksutow. Cooling down is no problem.
                  > >
                  >
                  > > > <snip>
                  > > > Heinz
                  > > >
                  > >
                  > > Hi Heinz,
                  > >
                  > > Interesting post! Thanks for sharing your many experiences.
                  > >
                  > > Yes, what if Tak made Maksutovs? I am surprised that Tak has
                  not
                  > > pushed themselves more, given that they are a top-tier telescope
                  > > maker. Although every design is a balance of compromises, I
                  would
                  > > think that Tak could have been more tilted towards the best
                  > > performance possible.
                  > >
                  > > Mark
                  > >
                  >
                • Greg Tober
                  Andrew, Great article!. Thanks for the tips. Just when I was about the eliminate a Mewlon from my choices and favor the Newt... If only I had unlimited
                  Message 8 of 28 , Jan 5, 2008
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                    Andrew,

                    Great article!. Thanks for the tips. Just when I was about the eliminate a Mewlon from my
                    choices and favor the Newt... If only I had unlimited funds - one scope at a time, I
                    suppose.

                    Living at almost 46deg N, I also have to look through a lot of atmosphere to observe some
                    of the best DSOs. Plus the Jet Stream and otherwise often windy conditions here in
                    Montana wreck havoc on seeing. That's why my chosen instruments have been 4-5" apos.
                    It sounds like you've experienced similar conditions. I'm concerned that a large Dob would
                    see only limited use on those rare nights of good seeing, or for dim low contrast DSOs.

                    I really appreciated your candor about the differences in mounts required for the M300 vs.
                    the 250 and/or 210; and synopsis about contrast's relationship to central obstructions.

                    Thanks again for contributing such a great article for the group.

                    Clear skies,
                    Greg

                    --- In UncensoredTakGroup@yahoogroups.com, "andyrobertson100" <alphacentauri@...>
                    wrote:
                    >
                    > Hi Greg,
                    >
                    > Did you read the article I posted in the articles section 2 days
                    > ago, " Apo Refractor-Reflector-Mewlon"? I discussed Mak-Newts in
                    > that article.
                    >
                    > Andrew.
                    >
                    > --- In UncensoredTakGroup@yahoogroups.com, "Greg Tober"
                    > <gtober6708@> wrote:
                    > >
                    > > Hello again Group! Thanks for all the great Mewlon information on
                    > this thread; it's much
                    > > appreciated.
                    > >
                    > > It's kind of off-topic, but I thought Heinz's and Mark's reference
                    > to Maksutovs was
                    > > interesting. My very first telescope, before about a 20 year
                    > hiatus from the hobby, was a
                    > > C90. I remember it being a great little scope. Other than very
                    > long cool-down and
                    > > stabilization times, I know they are generally regarded for
                    > excellent image quality across
                    > > the entire field. I know TEC used to produce these, and now ITE
                    > seems to have a corner on
                    > > the Mak market. Anyone have any experiences with 7" or larger Mak-
                    > Cas or Mak-Newts?
                    > >
                    > > Thanks again for all the great responses. It's groups like this
                    > that make researching for
                    > > that next scope almost as fun as actually observing through it.
                    > >
                    > > Greg T
                    > >
                    > > --- In UncensoredTakGroup@yahoogroups.com, "mark_1968"
                    > <mark_1968@> wrote:
                    > > >
                    > > > --- In UncensoredTakGroup@yahoogroups.com, Heinz Künzli
                    > > > <apus.tak@> wrote:
                    > > > >
                    > > > > Hi Greg, group
                    > > > ><snipped>
                    > > > >
                    > > > > In the case of the Mewlons, I think that Takahashi is wasting
                    > > > their ability to make fine telescopes
                    > > > > with the wrong optical design.
                    > > > > They should make Maksutows, instead of Dall-Kirkhams!
                    > > > > The added weight of a corrector is worth it, and the closed
                    > design
                    > > > is of no disadvantage, if you add proper ventilation,
                    > > > > as I did in the Intes Maksutow. Cooling down is no problem.
                    > > >
                    > >
                    > > > > <snip>
                    > > > > Heinz
                    > > > >
                    > > >
                    > > > Hi Heinz,
                    > > >
                    > > > Interesting post! Thanks for sharing your many experiences.
                    > > >
                    > > > Yes, what if Tak made Maksutovs? I am surprised that Tak has
                    > not
                    > > > pushed themselves more, given that they are a top-tier telescope
                    > > > maker. Although every design is a balance of compromises, I
                    > would
                    > > > think that Tak could have been more tilted towards the best
                    > > > performance possible.
                    > > >
                    > > > Mark
                    > > >
                    > >
                    >
                  • Phil Jones
                    Andrew, I would like to read this. Where is the articles section you reference? -Phil
                    Message 9 of 28 , Jan 5, 2008
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                      Andrew,

                      I would like to read this. Where is the "articles section" you reference?

                      -Phil

                      --- In UncensoredTakGroup@yahoogroups.com, "andyrobertson100"
                      <alphacentauri@...> wrote:
                      >
                      > Hi Greg,
                      >
                      > Did you read the article I posted in the articles section 2 days
                      > ago, " Apo Refractor-Reflector-Mewlon"? I discussed Mak-Newts in
                      > that article.
                      >
                      > Andrew
                    • andyrobertson100
                      It s in the files section about a third the way down entitled, Apo Refractor – Reflector – Mewlon Updated 2008 doc Andrew. ... reference?
                      Message 10 of 28 , Jan 6, 2008
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                        It's in the files section about a third the way down entitled,
                        "Apo Refractor – Reflector – Mewlon Updated 2008 doc"

                        Andrew.

                        --- In UncensoredTakGroup@yahoogroups.com, "Phil Jones"
                        <jediwebdude@...> wrote:
                        >
                        > Andrew,
                        >
                        > I would like to read this. Where is the "articles section" you
                        reference?
                        >
                        > -Phil
                        >
                        > --- In UncensoredTakGroup@yahoogroups.com, "andyrobertson100"
                        > <alphacentauri@> wrote:
                        > >
                        > > Hi Greg,
                        > >
                        > > Did you read the article I posted in the articles section 2 days
                        > > ago, " Apo Refractor-Reflector-Mewlon"? I discussed Mak-Newts in
                        > > that article.
                        > >
                        > > Andrew
                        >
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