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102, of course!

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  • gblt
    ... Please indulge me, and let me play the Grinch for a second here. The scope you should buy is the one with the biggest... wallet! The Stellarvue Carry-on
    Message 1 of 16 , Jan 1, 2002
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      --- In Stellarvue@y..., "starman1142001" <Tull1996@a...> wrote:

      > ...am hung up on which to get,,,the 1010, the 102D OR
      > even the 80 f/9.4......If I go for the 1010, I can get it fully
      > loaded for 995 (plus a few odds and ends that probably aren't
      > included), close to that for the f/9.4,,,,for the 102D, that same
      > outlay will get me the scope.


      Please indulge me, and let me play the Grinch for a second here. The
      scope you should buy is the one with the biggest... wallet!

      The Stellarvue Carry-on Case is said to be able to hold either the
      AT1010, or the 102 scopes. So portability is not an issue, as far as
      these two scopes, but rather, which can you afford (considering the
      cost of a "fully-loaded" system)?

      If you can afford the 102, then the issue becomes, the 80/9 or the
      102, right?

      Well, lemme tell ya sumthin', kid, that 80/9 is a wiry, tough
      fighter, but his vision is kinda limited, ya know what I mean?

      Whereas the 102, well now, we're talking possibilities, if ya get my
      drift... Plus, there's a lot more money ridin' on it.

      (All in jest, right?)

      GLB
    • k5apl
      ... I would recommend getting the 102D. The extra light gathering and transportability make it hard to beat In my opinion its a Best Buy. Regards, Wes
      Message 2 of 16 , Jan 1, 2002
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        --- In Stellarvue@y..., "starman1142001" <Tull1996@a...> wrote:
        > t. Any opinions from people who have
        > actually used all three? (or any of them for that matter!)
        >
        > Thanks!

        I would recommend getting the 102D. The extra light gathering
        and transportability make it hard to beat> In my opinion its
        a Best Buy.

        Regards,
        Wes
      • mikedche
        Hi! Well, I m one of the few that went for the 80mm f/9 version. My reasoning: 1. Apart from air travel, there isn t really a meaningful portability issue
        Message 3 of 16 , Jan 1, 2002
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          Hi!

          Well, I'm one of the few that went for the 80mm f/9 version. My
          reasoning:

          1. Apart from air travel, there isn't really a meaningful portability
          issue between the f/6 and f/9. Both are very light, small scopes.

          2. I have not directly compared the 80mm f/6 and f/9 scopes; but, as
          they are achromats, it is guaranteed that the f/9 will have better
          color correction. This is not only an issue of visible false color
          fringing. Better color correction means also slightly better
          planetary contrast and slightly fainter stars are visible.

          3. While the f/6 makes possible a wider field, the f/9.4 is still
          capable of almost a 3.5 degree field, which is pretty wide! A 40mm
          eyepiece gives about 19X in that scope; anything lower than that is
          sort of in binocular range anyway.

          4. The longer focal length will be more forgiving of inexpensive
          eyepieces at wide fields and low magnifications; and that is just the
          range where eyepieces are most expensive.

          Of course, when I made my selection, the 102D was not yet available.
          That throws a wrench into the whole thing! No question, the 102D will
          handily outperform either 80mm scope. There is only the cost issue.

          Best of luck!

          Mike
        • wmrroy
          Mike, I agree with your main thesis and in fact decided on the longer focal length SV85APO based on most of what you say here. In the interest of debate,
          Message 4 of 16 , Jan 1, 2002
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            Mike,

            I agree with your main thesis and in fact decided on the longer
            focal length SV85APO based on most of what you say here. In the
            interest of debate, however, I would add a bit to your points
            --- In Stellarvue@y..., "mikedche" <mikedamato@s...> wrote:
            >
            > 1. Apart from air travel, there isn't really a meaningful
            portability
            > issue between the f/6 and f/9. Both are very light, small scopes.

            If you are planning to use an alt/az mount like the Telepod, the extra
            10 inches of tube will make a difference. It's still certainly doable,
            but you'll find the difference in height between viewing at the zenith
            and at the horizon to be quite noticeable.


            > 2. I have not directly compared the 80mm f/6 and f/9 scopes; but, as
            > they are achromats, it is guaranteed that the f/9 will have better
            > color correction. This is not only an issue of visible false color
            > fringing. Better color correction means also slightly better
            > planetary contrast and slightly fainter stars are visible.

            Actually, if the lenses are really excellent on both, the only
            difference is the wider view of the faster scope. I agree that its'
            easier to achieve color better color correction with longer focal
            lengths, but it ain't necessarily so that it is guaranteed. That is
            why there are excellent F6APOs on the market today. Even a well
            corrected shorter focal length achromat with excellent optics can
            outperform a longer focal length achromat that is not as well
            corrected. This of course, is the source of much bitter debate on some
            of the other newsgroups. I don't know know about seeing fainter stars
            in a well corrected scope, I thought that was a functions of light
            grasp, but I certainly agree with you about planetary detail.


            > 3. While the f/6 makes possible a wider field, the f/9.4 is still
            > capable of almost a 3.5 degree field, which is pretty wide! A 40mm
            > eyepiece gives about 19X in that scope; anything lower than that is
            > sort of in binocular range anyway.

            You can drive a Mac truck through 3.5 degrees, huh?
            >
            > 4. The longer focal length will be more forgiving of inexpensive
            > eyepieces at wide fields and low magnifications; and that is just
            the
            > range where eyepieces are most expensive.

            That's one of the best reasons to go with the F9.4 IMO.

            Anyway these are just my opinions. Others vary and I respect and
            frankly enjoy that. That's how I learn.

            Randy
          • mikedche
            Hi Randy, ... extra ... That s true! I hadn t thought of that. An alt/az is not a bad idea since the scope does so well on terrestrial observation. ... I went
            Message 5 of 16 , Jan 1, 2002
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              Hi Randy,

              > If you are planning to use an alt/az mount like the Telepod, the
              extra
              > 10 inches of tube will make a difference.

              That's true! I hadn't thought of that. An alt/az is not a bad idea
              since the scope does so well on terrestrial observation.

              > Actually, if the lenses are really excellent on both, the only
              > difference is the wider view of the faster scope. I agree that its'
              > easier to achieve color better color correction with longer focal
              > lengths, but it ain't necessarily so that it is guaranteed. That is
              > why there are excellent F6APOs on the market today. Even a well
              > corrected shorter focal length achromat with excellent optics can
              > outperform a longer focal length achromat that is not as well
              > corrected.

              I went through all those "lively" threads by searching through SAA
              one time and I couldn't really distill a final answer out of all of
              it. It seemed to me that all the heavy-duty optical experts (Vic,
              Roland, Valery, etc.) were sort of talking past each other. The only
              firm conclusions I got from SAA were that Valery is kind of a funny
              duck, Roland is rather grumpy, and Vic might be a little over
              paranoid about someone stealing his trade secrets. I would be too if
              I worked 90 hour weeks.

              I went and tried to figure it all out by reading up on it and the
              best I could do was this: Although in the general case there is no
              guarantee that a longer focus achromat is going to have better
              correction than a shorter one, here we are comparing two of Vic's
              scopes - so I'm assuming that both the f/9 and f/6 are more or less
              perfectly optimized achromats, and that therefore the secondary
              spectrum in both is in the neighborhood of 0.0005f, with f being
              focal length. If that is the case then the diameter of the blur of
              unfocused blue and red light will be 0.0005D at the focal plane, with
              D being the objective diameter. However, the Airy disk diameter at
              the focal plane is larger in the scope with the longer focal length
              (given in millimeters by dA = (f/D)/735). In other words, for the
              same magnification in both scopes, the unfocused blur in the faster
              scope is larger compared to the size of the image.

              This is the logic that gave me the impression that, given the same
              level of correction (and I suppose it is safe to assume that all of
              Vic's achromats have the same level of color correction - i.e., the
              maximum possible for an achromat) the f/9 will have superior
              performance. This does not apply to those excellent f/6 APO's out
              there because their special dispersion glasses allow much better than
              0.0005f secondary spectrum, which throws a wrench into all this
              reasoning.

              On the other hand the Rutten & van Venrooij text is a little dense
              and maybe I have thoroughly misinterpreted it on this point...I'm no
              optician!

              > I don't know know about seeing fainter stars
              > in a well corrected scope, I thought that was a functions of light
              > grasp, but I certainly agree with you about planetary detail.

              Better color correction concentrates more of the light from a point
              source into a smaller area, which will supposedly increase the
              visibility of stars that are at the threshold of the scope's ability
              to detect. I don't know if the difference between an f/6 and f/9
              achromat is even visually detectable, though. People definitely
              report fainter limiting magnitudes with APO's then one would expect
              from the aperture - but the difference in color correction is much
              more pronounced then.

              > You can drive a Mac truck through 3.5 degrees, huh?

              Yep! I like to unlock the mount's axes and sweep around with a 40mm
              Pentax XL. Lovely!

              > > 4. The longer focal length will be more forgiving of inexpensive
              > > eyepieces at wide fields and low magnifications; and that is just
              > the
              > > range where eyepieces are most expensive.
              >
              > That's one of the best reasons to go with the F9.4 IMO.

              Yes. That 40mm Pentax, for example, while it still shows a little
              edge-of-field astigmatism at f/9, is frankly a poor performer in fast
              scopes. As far as I know so is everything else at low mags except
              Naglers and Panoptics. If I were to go and buy a $600
              eyepiece......oooooo mama, better hide THAT receipt!

              But anyway back to the original point of all this.....it is all too
              hard to decide so I suppose the original poster is just going to HAVE
              to get the 102 anyway. <G> That settles it!

              Mike

              Mike
            • jdbraddy
              ... If I were to go and buy a $600 ... WOW! Great minds do think alike! JDBraddy
              Message 6 of 16 , Jan 1, 2002
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                --- In Stellarvue@y..., "mikedche" <mikedamato@s...> wrote:
                If I were to go and buy a $600
                > eyepiece......oooooo mama, better hide THAT receipt!
                > Mike

                WOW! Great minds do think alike! JDBraddy
              • Mike Burley
                Randy wrote in part: ... I think the SV 80mm f/9.4 *will* guarantee you better color correction than the f/6. The SV APO s should be even better
                Message 7 of 16 , Jan 2, 2002
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                  Randy wrote in part:
                  <SNIP>
                  > Actually, if the lenses are really excellent on both, the only
                  > difference is the wider view of the faster scope. I agree that its'
                  > easier to achieve color better color correction with longer focal
                  > lengths, but it ain't necessarily so that it is guaranteed. That is
                  > why there are excellent F6APOs on the market today. Even a well
                  > corrected shorter focal length achromat with excellent optics can
                  > outperform a longer focal length achromat that is not as well
                  > corrected. This of course, is the source of much bitter debate on some
                  > of the other newsgroups. I don't know know about seeing fainter stars
                  > in a well corrected scope, I thought that was a functions of light
                  > grasp, but I certainly agree with you about planetary detail.
                  <SNIP>

                  I think the SV 80mm f/9.4 *will* guarantee you better color correction
                  than the f/6. The SV APO's should be even better in this regard, not
                  because of an f/6 focal ratio, but because this scope uses a three
                  element objective, utilizing exotic glasses. Longer f.l. APO's will
                  perform slightly better. The f/6 ratio is popular because of their wide
                  fields, and are easier to mount, while remaining essentially color free.

                  Mike in Oregon
                • ronbee77
                  Well, Starman, I ve been following the thread with interest. I used to experiment a great deal with my old el cheapo 102mm C102-HD achromat by making an
                  Message 8 of 16 , Jan 2, 2002
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                    Well, Starman, I've been following the thread with interest.
                    I used to experiment a great deal with my old el cheapo 102mm
                    C102-HD achromat by making an approx. 3" mask, obstructing and
                    ultimating destructing it ;-). I can tell you with certainty
                    that the difference in aperture is (very* noticable. The 102mm
                    will give a noticably higher resolution and brighter image. Since
                    this will be your first (and only?) scope, my vote would be to
                    go with the 102D unless utmost portability is your main requirement.
                    Having said all of these, the 80mm is no slouch at all (via my
                    aperture mask). Although, I didn't experiment with DSO, the 102mm
                    will let you look a deeper as well and make the dimmest of dim
                    brighter ;-).

                    BTW, you can achieve "fully loaded" status incrementally.

                    Ron B[ee]

                    --- In Stellarvue@y..., "starman1142001" <Tull1996@a...> wrote:
                    > Hi Everyone,,,,Im new to all of this. Getting ready to purchase
                    > first scope and am hung up on which to get,,,the 1010, the 102D OR
                    > even the 80 f/9.4......If I go for the 1010, I can get it fully
                    > loaded for 995 (plus a few odds and ends that probably aren't
                    > included), close to that for the f/9.4,,,,for the 102D, that same
                    > outlay will get me the scope. However, if it's worth the jump, I
                    > might be willing to go for it. Any opinions from people who have
                    > actually used all three? (or any of them for that matter!)
                    >
                    > Thanks!
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