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Sometimes it seems like I'm going backwards...

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  • foto_phoca
    I ve been practicing drift aligning and pretty much have the process down thanks to the great writeup at m1.aol.com/kewtasheck/drift.html But I was in for a
    Message 1 of 15 , Feb 1, 2005
      I've been practicing drift aligning and pretty much have the process
      down thanks to the great writeup at m1.aol.com/kewtasheck/drift.html

      But I was in for a rude suprise, though in retrospect it makes sense.
      Drift aligning after doing a two star alignment throws the GoTo off
      by the exact amount that you had to adjust during the drift
      alignment. So once I get perfect drift alignment, the GoTo is off,
      sometimes too far off to really be useable.f

      I havent seen this really mentioned anywhere. But what is the
      interplay between the built in alignment of the autostar and drift
      alignment? Is it one or the other exclusively? (And does GoTo work
      after only a drift alignment?) Or do you do a two star, then drift,
      then two star again(After repositioning the scope to 0 RA and 90 Dec
      of course)? And then maybe drift again?

      I ask the group: What is YOUR method of obtaining simultaneous
      perfect tracking (perfect polar alignment) AND perfect GoTo on a
      polar wedge?
    • Peter Vasey
      Hi, ?, Any repositioning of the mount after the initial two star alignment is bound to throw off the GOTOs - you ve altered the position of the scope with
      Message 2 of 15 , Feb 1, 2005
        Hi, ?,

        Any repositioning of the mount after the initial two star alignment is
        bound to throw off the GOTOs - you've altered the position of the 'scope
        with respect to the sky, and the Autostar doesn't know by how much.

        Drift alignment serves to accurately line up the polar axis of the fork
        with the celestial pole. So once you are happy with the alignment,
        simply redo the two star alignment. No need to redo the drift - your
        mount remains polar aligned from the previous drift alignment.

        HTH, Peter.

        foto_phoca wrote:

        >I've been practicing drift aligning and pretty much have the process
        >down thanks to the great writeup at m1.aol.com/kewtasheck/drift.html
        >
        >But I was in for a rude suprise, though in retrospect it makes sense.
        >Drift aligning after doing a two star alignment throws the GoTo off
        >by the exact amount that you had to adjust during the drift
        >alignment. So once I get perfect drift alignment, the GoTo is off,
        >sometimes too far off to really be useable.f
        >
        >I havent seen this really mentioned anywhere. But what is the
        >interplay between the built in alignment of the autostar and drift
        >alignment? Is it one or the other exclusively? (And does GoTo work
        >after only a drift alignment?) Or do you do a two star, then drift,
        >then two star again(After repositioning the scope to 0 RA and 90 Dec
        >of course)? And then maybe drift again?
        >
        >I ask the group: What is YOUR method of obtaining simultaneous
        >perfect tracking (perfect polar alignment) AND perfect GoTo on a
        >polar wedge?
        >
        >
        >
        >
      • autostaretx
        ... My suggestion would be that you PARK the telescope. That sets the OTA at the Autostar s idea of -exactly- Dec=90. Then power-off (count to 5) power-on. It
        Message 3 of 15 , Feb 1, 2005
          --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
          ...
          > I ask the group: What is YOUR method of obtaining simultaneous
          > perfect tracking (perfect polar alignment) AND perfect GoTo on a
          > polar wedge?

          My suggestion would be that you PARK the telescope.
          That sets the OTA at the Autostar's idea of -exactly- Dec=90.

          Then power-off (count to 5) power-on.
          It won't offer to Align (since you PARKed), but you can
          mode/menu to Setup/Align.

          Now the puzzle (and you'll have to -try- these, my wedge and
          ETX90 can't achieve enough accuracy to test accurately).
          (a) One Star? This would be my first suggestion... it tells
          the Autostar that you -know- your mount is accurately positioned.
          I would -not- adjust the mount during the first slew to "Polaris",
          i'd just tap [enter] as if it were centered.

          (b) Two Star? This should obviously work, but adds a slight
          potential error in the calculations due to the math involved

          (c) No Star? Don't align... when it prompts "Object", GoTo
          a star kind'a near the equator and SYNC on it.

          For that matter, simply SYNCing on two stars (one near equator,
          but eastish, the other westish, at least 45 degrees (3 RA hours)
          apart) after the drift-align may well do it.

          have fun
          --dick
        • foto_phoca
          I hadn t though about the SYNCing, that sounds like a fun experiment :) I ll try these out tonight and report what happens. Thanks! Larry
          Message 4 of 15 , Feb 1, 2005
            I hadn't though about the SYNCing, that sounds like a fun
            experiment :)

            I'll try these out tonight and report what happens. Thanks!

            Larry

            --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
            >
            > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
            > ...
            > > I ask the group: What is YOUR method of obtaining simultaneous
            > > perfect tracking (perfect polar alignment) AND perfect GoTo on a
            > > polar wedge?
            >
            > My suggestion would be that you PARK the telescope.
            > That sets the OTA at the Autostar's idea of -exactly- Dec=90.
            >
            > Then power-off (count to 5) power-on.
            > It won't offer to Align (since you PARKed), but you can
            > mode/menu to Setup/Align.
            >
            > Now the puzzle (and you'll have to -try- these, my wedge and
            > ETX90 can't achieve enough accuracy to test accurately).
            > (a) One Star? This would be my first suggestion... it tells
            > the Autostar that you -know- your mount is accurately positioned.
            > I would -not- adjust the mount during the first slew to "Polaris",
            > i'd just tap [enter] as if it were centered.
            >
            > (b) Two Star? This should obviously work, but adds a slight
            > potential error in the calculations due to the math involved
            >
            > (c) No Star? Don't align... when it prompts "Object", GoTo
            > a star kind'a near the equator and SYNC on it.
            >
            > For that matter, simply SYNCing on two stars (one near equator,
            > but eastish, the other westish, at least 45 degrees (3 RA hours)
            > apart) after the drift-align may well do it.
            >
            > have fun
            > --dick
          • foto_phoca
            Hi, Yeah in retrospect, the drift throwing off the GoTo seems obvious, but I hand t thought forward enough to realise that would happen beforehand :) Was one
            Message 5 of 15 , Feb 1, 2005
              Hi,

              Yeah in retrospect, the drift throwing off the GoTo seems obvious,
              but I hand't thought forward enough to realise that would happen
              beforehand :) Was one of those "Oh no" feelings when it sinks in...

              One thing that worries me is that a two star alignment is already
              trying to correct for a pole misalignment and drift aligning
              afterwards will not really get you polar aligned. Does that make
              sense?

              As someone else replied, it seems like the best thing to do would be
              to get the scope perfectly oriented on the mount by parking it then
              hand adjusting to 0 RA and 90 DEC, visually align on the celestial
              pole, drift align to get a true polar alignment, then do a two star
              or sync on a star to get the goto working?

              With normal eyepieces the amount that GoTo is off isn't that
              critical, it's not off by so much that it isn't easy to find in a
              wide angle eyepiece. But when using the camera, I am frequently
              forced to move the scope to a bright star to focus (When using
              eyepiece projection epecially) then move back to the object which is
              completely invisible in the viewfinder, and hunting around for it by
              taking pictures can take forever! :)

              Which reminds me, wouldn't it be nice to have a quick way to mark a
              position and return to it! Like with just a couple of button presses
              (I know you can program a custom position but...) That way, aligning
              with an eyepiece, moving off to a bright star, mounting camera,
              focusing and moving back would be a lot faster :)

              --- In lx90@yahoogroups.com, Peter Vasey <Peter@p...> wrote:
              > Hi, ?,
              >
              > Any repositioning of the mount after the initial two star alignment
              is
              > bound to throw off the GOTOs - you've altered the position of
              the 'scope
              > with respect to the sky, and the Autostar doesn't know by how much.
              >
              > Drift alignment serves to accurately line up the polar axis of the
              fork
              > with the celestial pole. So once you are happy with the alignment,
              > simply redo the two star alignment. No need to redo the drift -
              your
              > mount remains polar aligned from the previous drift alignment.
              >
              > HTH, Peter.
              >
            • noddaduma
              Hi Larry, Since your scope is polar mounted, you may want to consider One Star alignment. I ve found that this is extremely accurate if I use a high-powered
              Message 6 of 15 , Feb 1, 2005
                Hi Larry,

                Since your scope is polar mounted, you may want to consider One Star
                alignment. I've found that this is extremely accurate if I use a
                high-powered eyepiece (I use a 9mm reticled eyepiece) to center
                Polaris and the Alignment Star. The reason is that I am removing as
                much misalignment as possible when centering on Polaris. I make sure
                that the scope is levelled and that the time I enter is accurate.

                In addition, I take extra care in making sure that the OTA is
                perpendicular to the RA axis (that is, above and beyond making sure
                that the OTA is aligned with the forks). I do this by centering on
                Polaris before turning the scope on, loosening the RA axis, and
                spinning the OTA while looking through the eyepiece. If the OTA is
                perfectly perpendicular to the RA axis, then Polaris will stay
                centered in the FOV while the rest of the view rotates around it. If
                not aligned, then Polaris will scribe an imaginary circle around the
                point that the center of the FOV needs to be at. You then adjust the
                OTA either up or down by loosening the DEC clutch and adjusting the
                OTA. This I think is critical for accurate alignment, and it doesn't
                take very long at all once you get the technique down. You then
                power up the scope and enter in date and accurate time (I use one of
                those $20 radio clocks that is accurate within a second), and then do
                One Star alignment with a high-power eyepiece. There is no guessing
                on how close you are initially polar aligned because in centering
                Polaris you basically make the scope a closed-loop system. This is
                the real (and significant) advantage of One Star alignment. Two Star
                alignment doesn't check how well you are polar aligned...you must
                depend on drift or iterative alignment after setup is complete.
                This, of course, will throw off GOTO as you have noticed. Once you
                are accurately polar aligned with One Star alignment, the scope
                really only needs alignment on a single star to make GOTOs accurate
                enough.

                It will probably take a few attempts to get the setup down, but I
                think it's worth it. I consistently detect little or no drift after
                5 minutes since I've started setting up the scope this way. 5
                minutes of no drift is good enough for a 1 or 2 hour exposure without
                any field rotation showing up in the picture (I do film
                astrophotography, so this is important for me). Plus, I don't have
                to spend the time needed to do drift alignment...which can be a lot
                of time to get to 5 minutes of no drift.

                Hope this helps,
                Jason


                --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                >
                > I hadn't though about the SYNCing, that sounds like a fun
                > experiment :)
                >
                > I'll try these out tonight and report what happens. Thanks!
                >
                > Larry
                >
                > --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                > >
                > > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                > > ...
                > > > I ask the group: What is YOUR method of obtaining simultaneous
                > > > perfect tracking (perfect polar alignment) AND perfect GoTo on
                a
                > > > polar wedge?
                > >
                > > My suggestion would be that you PARK the telescope.
                > > That sets the OTA at the Autostar's idea of -exactly- Dec=90.
                > >
                > > Then power-off (count to 5) power-on.
                > > It won't offer to Align (since you PARKed), but you can
                > > mode/menu to Setup/Align.
                > >
                > > Now the puzzle (and you'll have to -try- these, my wedge and
                > > ETX90 can't achieve enough accuracy to test accurately).
                > > (a) One Star? This would be my first suggestion... it tells
                > > the Autostar that you -know- your mount is accurately positioned.
                > > I would -not- adjust the mount during the first slew
                to "Polaris",
                > > i'd just tap [enter] as if it were centered.
                > >
                > > (b) Two Star? This should obviously work, but adds a slight
                > > potential error in the calculations due to the math involved
                > >
                > > (c) No Star? Don't align... when it prompts "Object", GoTo
                > > a star kind'a near the equator and SYNC on it.
                > >
                > > For that matter, simply SYNCing on two stars (one near equator,
                > > but eastish, the other westish, at least 45 degrees (3 RA hours)
                > > apart) after the drift-align may well do it.
                > >
                > > have fun
                > > --dick
              • autostaretx
                ... No. Drift Aligning helps you to get your physical mount correctly aligned to the pole (the RA axle pointed properly). Two Star aligning aligns the
                Message 7 of 15 , Feb 1, 2005
                  --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:

                  > One thing that worries me is that a two star alignment is already
                  > trying to correct for a pole misalignment and drift aligning
                  > afterwards will not really get you polar aligned. Does that make
                  > sense?

                  No. Drift Aligning helps you to get your physical mount
                  correctly aligned to the pole (the RA axle pointed properly).

                  "Two Star" aligning aligns the GoTo's.

                  Once you've GoneTo, the "two Star" stops having any effect.
                  All that's left now is the sidereal drive moving the scope
                  westward. If you're drift aligned, the star shouldn't move
                  up or down (north/south) in the field of view.

                  Your Two Star can be quite a bit "off", and that won't affect
                  tracking (i.e. photography) at all. Once the GoTo has finished
                  slewing, only -one- motor will be running.

                  You could probably -ignore- the second after-drift Two Star
                  by simply engaging "High Precision"... it'll GoTo a guide star,
                  you center, and then it goes to the target. It'll be quite
                  accurate.

                  > As someone else replied, it seems like the best thing to do would be
                  > to get the scope perfectly oriented on the mount by parking it then
                  > hand adjusting to 0 RA and 90 DEC,

                  PARKing -will- set it to HA=0 (that's Hour Angle, not RA)
                  and DEC=90. No manual adjustment needed.

                  > visually align on the celestial
                  > pole, drift align to get a true polar alignment, then do a two star
                  > or sync on a star to get the goto working?
                  >
                  > With normal eyepieces the amount that GoTo is off isn't that
                  > critical, it's not off by so much that it isn't easy to find in a
                  > wide angle eyepiece. But when using the camera, I am frequently
                  > forced to move the scope to a bright star to focus (When using
                  > eyepiece projection epecially) then move back to the object which is
                  > completely invisible in the viewfinder, and hunting around for it by
                  > taking pictures can take forever! :)

                  So why not use High Precision? It automates that process.
                  Folks report that it drops the final target onto the CCD with
                  great regularity.

                  > Which reminds me, wouldn't it be nice to have a quick way to mark a
                  > position and return to it! Like with just a couple of button presses
                  > (I know you can program a custom position but...) That way, aligning
                  > with an eyepiece, moving off to a bright star, mounting camera,
                  > focusing and moving back would be a lot faster :)

                  Simple... GoTo your target. Fiddle ("align") as you wish. SYNC.
                  SLEW (not GoTo) to the bright star. Mount camera, focus.
                  Tap [GoTo]. It will return to the original target.

                  Personally, i'd use High Precision:
                  (a) GoTo target (it'll detour via the brighter star)
                  (b) assuming it centers, slew away a bit.
                  (c) tap [goto]. It will -return- to the bright star.
                  (d) mount camera. focus. center. Tap [enter]
                  (e) scope will go to final target.

                  You may find that High Prec lets you reduce that to:
                  (a) GoTo target (it'll detour via the brighter star)
                  (b) mount camera. focus. center. Tap [enter]
                  (c) scope will go to final target, which will be centered.

                  Try it.

                  have fun
                  --dick
                • foto_phoca
                  Huh, That s an interesting method! I would love to not spend the 45-60 minutes doing a drift align if possible. I really only want to take steady unguided
                  Message 8 of 15 , Feb 1, 2005
                    Huh,

                    That's an interesting method!

                    I would love to not spend the 45-60 minutes doing a drift align if
                    possible. I really only want to take steady unguided pictures for at
                    most about 2 minutes at maybe 150x, and gave goto spot on. I've got a
                    little hand held GPS that gives me the exact location and time so I
                    know that part is accurate.

                    So just to be clear, using the method below you get the scope
                    perfectly aligned with polaris with the autostar off (not the true
                    polar axis) then turn on the autostar and do a single star alignment
                    (Somewhere along the meridian I assume?) and that's good to go?

                    I'll give that one a try too. Thanks!

                    Larry

                    --- In lx90@yahoogroups.com, "noddaduma" <noddaduma@y...> wrote:
                    >
                    >
                    > Hi Larry,
                    >
                    > Since your scope is polar mounted, you may want to consider One
                    Star
                    > alignment. I've found that this is extremely accurate if I use a
                    > high-powered eyepiece (I use a 9mm reticled eyepiece) to center
                    > Polaris and the Alignment Star. The reason is that I am removing
                    as
                    > much misalignment as possible when centering on Polaris. I make
                    sure
                    > that the scope is levelled and that the time I enter is accurate.
                    >
                    > In addition, I take extra care in making sure that the OTA is
                    > perpendicular to the RA axis (that is, above and beyond making sure
                    > that the OTA is aligned with the forks). I do this by centering on
                    > Polaris before turning the scope on, loosening the RA axis, and
                    > spinning the OTA while looking through the eyepiece. If the OTA is
                    > perfectly perpendicular to the RA axis, then Polaris will stay
                    > centered in the FOV while the rest of the view rotates around it.
                    If
                    > not aligned, then Polaris will scribe an imaginary circle around
                    the
                    > point that the center of the FOV needs to be at. You then adjust
                    the
                    > OTA either up or down by loosening the DEC clutch and adjusting the
                    > OTA. This I think is critical for accurate alignment, and it
                    doesn't
                    > take very long at all once you get the technique down. You then
                    > power up the scope and enter in date and accurate time (I use one
                    of
                    > those $20 radio clocks that is accurate within a second), and then
                    do
                    > One Star alignment with a high-power eyepiece. There is no
                    guessing
                    > on how close you are initially polar aligned because in centering
                    > Polaris you basically make the scope a closed-loop system. This is
                    > the real (and significant) advantage of One Star alignment. Two
                    Star
                    > alignment doesn't check how well you are polar aligned...you must
                    > depend on drift or iterative alignment after setup is complete.
                    > This, of course, will throw off GOTO as you have noticed. Once you
                    > are accurately polar aligned with One Star alignment, the scope
                    > really only needs alignment on a single star to make GOTOs accurate
                    > enough.
                    >
                    > It will probably take a few attempts to get the setup down, but I
                    > think it's worth it. I consistently detect little or no drift
                    after
                    > 5 minutes since I've started setting up the scope this way. 5
                    > minutes of no drift is good enough for a 1 or 2 hour exposure
                    without
                    > any field rotation showing up in the picture (I do film
                    > astrophotography, so this is important for me). Plus, I don't have
                    > to spend the time needed to do drift alignment...which can be a lot
                    > of time to get to 5 minutes of no drift.
                    >
                    > Hope this helps,
                    > Jason
                    >
                    >
                    > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                    > >
                    > > I hadn't though about the SYNCing, that sounds like a fun
                    > > experiment :)
                    > >
                    > > I'll try these out tonight and report what happens. Thanks!
                    > >
                    > > Larry
                    > >
                    > > --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                    > > >
                    > > > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                    > > > ...
                    > > > > I ask the group: What is YOUR method of obtaining
                    simultaneous
                    > > > > perfect tracking (perfect polar alignment) AND perfect GoTo
                    on
                    > a
                    > > > > polar wedge?
                    > > >
                    > > > My suggestion would be that you PARK the telescope.
                    > > > That sets the OTA at the Autostar's idea of -exactly- Dec=90.
                    > > >
                    > > > Then power-off (count to 5) power-on.
                    > > > It won't offer to Align (since you PARKed), but you can
                    > > > mode/menu to Setup/Align.
                    > > >
                    > > > Now the puzzle (and you'll have to -try- these, my wedge and
                    > > > ETX90 can't achieve enough accuracy to test accurately).
                    > > > (a) One Star? This would be my first suggestion... it tells
                    > > > the Autostar that you -know- your mount is accurately
                    positioned.
                    > > > I would -not- adjust the mount during the first slew
                    > to "Polaris",
                    > > > i'd just tap [enter] as if it were centered.
                    > > >
                    > > > (b) Two Star? This should obviously work, but adds a slight
                    > > > potential error in the calculations due to the math involved
                    > > >
                    > > > (c) No Star? Don't align... when it prompts "Object", GoTo
                    > > > a star kind'a near the equator and SYNC on it.
                    > > >
                    > > > For that matter, simply SYNCing on two stars (one near equator,
                    > > > but eastish, the other westish, at least 45 degrees (3 RA hours)
                    > > > apart) after the drift-align may well do it.
                    > > >
                    > > > have fun
                    > > > --dick
                  • foto_phoca
                    More good info! I m running out of ink printing this all out. Meade aught to have the group write their next manual. Each autostar option has a one or two
                    Message 9 of 15 , Feb 1, 2005
                      More good info! I'm running out of ink printing this all out.

                      Meade aught to have the group write their next manual. Each autostar
                      option has a one or two sentence description about what it does but
                      very little about how they all tie togeather or are best used in
                      actual practice.

                      Thanks.

                      --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                      >
                      > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                      >
                      > > One thing that worries me is that a two star alignment is already
                      > > trying to correct for a pole misalignment and drift aligning
                      > > afterwards will not really get you polar aligned. Does that make
                      > > sense?
                      >
                      > No. Drift Aligning helps you to get your physical mount
                      > correctly aligned to the pole (the RA axle pointed properly).
                      >
                      > "Two Star" aligning aligns the GoTo's.
                      >
                      > Once you've GoneTo, the "two Star" stops having any effect.
                      > All that's left now is the sidereal drive moving the scope
                      > westward. If you're drift aligned, the star shouldn't move
                      > up or down (north/south) in the field of view.
                      >
                      > Your Two Star can be quite a bit "off", and that won't affect
                      > tracking (i.e. photography) at all. Once the GoTo has finished
                      > slewing, only -one- motor will be running.
                      >
                      > You could probably -ignore- the second after-drift Two Star
                      > by simply engaging "High Precision"... it'll GoTo a guide star,
                      > you center, and then it goes to the target. It'll be quite
                      > accurate.
                      >
                      > > As someone else replied, it seems like the best thing to do would
                      be
                      > > to get the scope perfectly oriented on the mount by parking it
                      then
                      > > hand adjusting to 0 RA and 90 DEC,
                      >
                      > PARKing -will- set it to HA=0 (that's Hour Angle, not RA)
                      > and DEC=90. No manual adjustment needed.
                      >
                      > > visually align on the celestial
                      > > pole, drift align to get a true polar alignment, then do a two
                      star
                      > > or sync on a star to get the goto working?
                      > >
                      > > With normal eyepieces the amount that GoTo is off isn't that
                      > > critical, it's not off by so much that it isn't easy to find in a
                      > > wide angle eyepiece. But when using the camera, I am frequently
                      > > forced to move the scope to a bright star to focus (When using
                      > > eyepiece projection epecially) then move back to the object which
                      is
                      > > completely invisible in the viewfinder, and hunting around for it
                      by
                      > > taking pictures can take forever! :)
                      >
                      > So why not use High Precision? It automates that process.
                      > Folks report that it drops the final target onto the CCD with
                      > great regularity.
                      >
                      > > Which reminds me, wouldn't it be nice to have a quick way to mark
                      a
                      > > position and return to it! Like with just a couple of button
                      presses
                      > > (I know you can program a custom position but...) That way,
                      aligning
                      > > with an eyepiece, moving off to a bright star, mounting camera,
                      > > focusing and moving back would be a lot faster :)
                      >
                      > Simple... GoTo your target. Fiddle ("align") as you wish. SYNC.
                      > SLEW (not GoTo) to the bright star. Mount camera, focus.
                      > Tap [GoTo]. It will return to the original target.
                      >
                      > Personally, i'd use High Precision:
                      > (a) GoTo target (it'll detour via the brighter star)
                      > (b) assuming it centers, slew away a bit.
                      > (c) tap [goto]. It will -return- to the bright star.
                      > (d) mount camera. focus. center. Tap [enter]
                      > (e) scope will go to final target.
                      >
                      > You may find that High Prec lets you reduce that to:
                      > (a) GoTo target (it'll detour via the brighter star)
                      > (b) mount camera. focus. center. Tap [enter]
                      > (c) scope will go to final target, which will be centered.
                      >
                      > Try it.
                      >
                      > have fun
                      > --dick
                    • noddaduma
                      Hi Larry, Not quite. One Star alignment is built into autostar (same as Two Star or Easy alignment). I initially use Polaris just to make sure the OTA is
                      Message 10 of 15 , Feb 1, 2005
                        Hi Larry,

                        Not quite. One Star alignment is built into autostar (same as Two
                        Star or Easy alignment). I initially use Polaris just to make sure
                        the OTA is perpendicular to the RA axis (aka "aligned with the
                        forks"), but I could really use any star within the vicinity.
                        Polaris is just easiest to see. I then turn Autostar on and after
                        entering time and date I select "Setup->One Star Alignment". One
                        Star setup will line your scope up with the true polar axis as the
                        first step, and then selects an alignment star (much like Two Star
                        alignment) to dial in the GOTO.

                        I'm not sure what alignment stars are used for One Star alignment,
                        but yeah I think they are probably along or near the Meridian. It
                        used to select Vega during the fall in the evenings, if that gives
                        you an idea. Of course now I think it selects a star farther east
                        (haven't been able to take the scope out recently and I don't
                        remember from last year).

                        As a side note, I also use high precision pointing since framing the
                        dim objects I want to take pictures of can be difficult. High
                        Precision is extremely accurate.

                        By the way, you will be hard-pressed to take good 2 minute unguided
                        exposures even at 150x. The drive accuracy (due to periodic error)
                        on the LX90 is good enough for maybe 30-45 seconds...at least I
                        haven't heard of anyone having unguided exposures longer than that.
                        I would recommend you try manually guiding through the 2 minute
                        exposures using an off-axis guider. 2 minutes isn't a lot of time
                        (now 60 minutes is, although beer helps), and it isn't very
                        difficult. When I was manually guiding I think I made corrections
                        once every 15-30 seconds, depending on where I was on the worm gear.

                        Hope this helps,
                        Jason


                        --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                        >
                        > Huh,
                        >
                        > That's an interesting method!
                        >
                        > I would love to not spend the 45-60 minutes doing a drift align if
                        > possible. I really only want to take steady unguided pictures for
                        at
                        > most about 2 minutes at maybe 150x, and gave goto spot on. I've got
                        a
                        > little hand held GPS that gives me the exact location and time so I
                        > know that part is accurate.
                        >
                        > So just to be clear, using the method below you get the scope
                        > perfectly aligned with polaris with the autostar off (not the true
                        > polar axis) then turn on the autostar and do a single star
                        alignment
                        > (Somewhere along the meridian I assume?) and that's good to go?
                        >
                        > I'll give that one a try too. Thanks!
                        >
                        > Larry
                        >
                        > --- In lx90@yahoogroups.com, "noddaduma" <noddaduma@y...> wrote:
                        > >
                        > >
                        > > Hi Larry,
                        > >
                        > > Since your scope is polar mounted, you may want to consider One
                        > Star
                        > > alignment. I've found that this is extremely accurate if I use a
                        > > high-powered eyepiece (I use a 9mm reticled eyepiece) to center
                        > > Polaris and the Alignment Star. The reason is that I am removing
                        > as
                        > > much misalignment as possible when centering on Polaris. I make
                        > sure
                        > > that the scope is levelled and that the time I enter is
                        accurate.
                        > >
                        > > In addition, I take extra care in making sure that the OTA is
                        > > perpendicular to the RA axis (that is, above and beyond making
                        sure
                        > > that the OTA is aligned with the forks). I do this by centering
                        on
                        > > Polaris before turning the scope on, loosening the RA axis, and
                        > > spinning the OTA while looking through the eyepiece. If the OTA
                        is
                        > > perfectly perpendicular to the RA axis, then Polaris will stay
                        > > centered in the FOV while the rest of the view rotates around
                        it.
                        > If
                        > > not aligned, then Polaris will scribe an imaginary circle around
                        > the
                        > > point that the center of the FOV needs to be at. You then adjust
                        > the
                        > > OTA either up or down by loosening the DEC clutch and adjusting
                        the
                        > > OTA. This I think is critical for accurate alignment, and it
                        > doesn't
                        > > take very long at all once you get the technique down. You then
                        > > power up the scope and enter in date and accurate time (I use one
                        > of
                        > > those $20 radio clocks that is accurate within a second), and
                        then
                        > do
                        > > One Star alignment with a high-power eyepiece. There is no
                        > guessing
                        > > on how close you are initially polar aligned because in centering
                        > > Polaris you basically make the scope a closed-loop system. This
                        is
                        > > the real (and significant) advantage of One Star alignment. Two
                        > Star
                        > > alignment doesn't check how well you are polar aligned...you must
                        > > depend on drift or iterative alignment after setup is complete.
                        > > This, of course, will throw off GOTO as you have noticed. Once
                        you
                        > > are accurately polar aligned with One Star alignment, the scope
                        > > really only needs alignment on a single star to make GOTOs
                        accurate
                        > > enough.
                        > >
                        > > It will probably take a few attempts to get the setup down, but I
                        > > think it's worth it. I consistently detect little or no drift
                        > after
                        > > 5 minutes since I've started setting up the scope this way. 5
                        > > minutes of no drift is good enough for a 1 or 2 hour exposure
                        > without
                        > > any field rotation showing up in the picture (I do film
                        > > astrophotography, so this is important for me). Plus, I don't
                        have
                        > > to spend the time needed to do drift alignment...which can be a
                        lot
                        > > of time to get to 5 minutes of no drift.
                        > >
                        > > Hope this helps,
                        > > Jason
                        > >
                        > >
                        > > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                        > > >
                        > > > I hadn't though about the SYNCing, that sounds like a fun
                        > > > experiment :)
                        > > >
                        > > > I'll try these out tonight and report what happens. Thanks!
                        > > >
                        > > > Larry
                        > > >
                        > > > --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...>
                        wrote:
                        > > > >
                        > > > > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                        > > > > ...
                        > > > > > I ask the group: What is YOUR method of obtaining
                        > simultaneous
                        > > > > > perfect tracking (perfect polar alignment) AND perfect GoTo
                        > on
                        > > a
                        > > > > > polar wedge?
                        > > > >
                        > > > > My suggestion would be that you PARK the telescope.
                        > > > > That sets the OTA at the Autostar's idea of -exactly- Dec=90.
                        > > > >
                        > > > > Then power-off (count to 5) power-on.
                        > > > > It won't offer to Align (since you PARKed), but you can
                        > > > > mode/menu to Setup/Align.
                        > > > >
                        > > > > Now the puzzle (and you'll have to -try- these, my wedge and
                        > > > > ETX90 can't achieve enough accuracy to test accurately).
                        > > > > (a) One Star? This would be my first suggestion... it tells
                        > > > > the Autostar that you -know- your mount is accurately
                        > positioned.
                        > > > > I would -not- adjust the mount during the first slew
                        > > to "Polaris",
                        > > > > i'd just tap [enter] as if it were centered.
                        > > > >
                        > > > > (b) Two Star? This should obviously work, but adds a slight
                        > > > > potential error in the calculations due to the math involved
                        > > > >
                        > > > > (c) No Star? Don't align... when it prompts "Object", GoTo
                        > > > > a star kind'a near the equator and SYNC on it.
                        > > > >
                        > > > > For that matter, simply SYNCing on two stars (one near
                        equator,
                        > > > > but eastish, the other westish, at least 45 degrees (3 RA
                        hours)
                        > > > > apart) after the drift-align may well do it.
                        > > > >
                        > > > > have fun
                        > > > > --dick
                      • foto_phoca
                        Yah, I can remember manually guiding my fathers scope for 30-60 minutes at a time. I haven t gotten to the point of doing a PEC correction to the lx90 yet, but
                        Message 11 of 15 , Feb 1, 2005
                          Yah, I can remember manually guiding my fathers scope for 30-60
                          minutes at a time. I haven't gotten to the point of doing a PEC
                          correction to the lx90 yet, but that is at least only a 9 minute
                          guide, once per evening. Too bad it doesn't remember, but that's
                          still better than doing it constanly all night :) Of course I'm
                          hoping that if I can get at least 4 out ot 5 60-90 second images
                          stable enough at about 150x, I'd be very happy. Right now at prime
                          focus (about 75x?) I can get about 5 out of 10 with round stars if
                          I'm lucky and sometimes it's as low as 2 out of 10 like last night.
                          That's a little frustrating.

                          Just need more practice.

                          Larry

                          --- In lx90@yahoogroups.com, "noddaduma" <noddaduma@y...> wrote:
                          >
                          > Hi Larry,
                          >
                          > Not quite. One Star alignment is built into autostar (same as Two
                          > Star or Easy alignment). I initially use Polaris just to make sure
                          > the OTA is perpendicular to the RA axis (aka "aligned with the
                          > forks"), but I could really use any star within the vicinity.
                          > Polaris is just easiest to see. I then turn Autostar on and after
                          > entering time and date I select "Setup->One Star Alignment". One
                          > Star setup will line your scope up with the true polar axis as the
                          > first step, and then selects an alignment star (much like Two Star
                          > alignment) to dial in the GOTO.
                          >
                          > I'm not sure what alignment stars are used for One Star alignment,
                          > but yeah I think they are probably along or near the Meridian. It
                          > used to select Vega during the fall in the evenings, if that gives
                          > you an idea. Of course now I think it selects a star farther east
                          > (haven't been able to take the scope out recently and I don't
                          > remember from last year).
                          >
                          > As a side note, I also use high precision pointing since framing
                          the
                          > dim objects I want to take pictures of can be difficult. High
                          > Precision is extremely accurate.
                          >
                          > By the way, you will be hard-pressed to take good 2 minute unguided
                          > exposures even at 150x. The drive accuracy (due to periodic error)
                          > on the LX90 is good enough for maybe 30-45 seconds...at least I
                          > haven't heard of anyone having unguided exposures longer than
                          that.
                          > I would recommend you try manually guiding through the 2 minute
                          > exposures using an off-axis guider. 2 minutes isn't a lot of time
                          > (now 60 minutes is, although beer helps), and it isn't very
                          > difficult. When I was manually guiding I think I made corrections
                          > once every 15-30 seconds, depending on where I was on the worm gear.
                          >
                          > Hope this helps,
                          > Jason
                          >
                          >
                        • autostaretx
                          ... Um... it DOES remember. All you have to do is PARK the scope at the end of your session to keep the PEC index properly retained. (you can then unclamp and
                          Message 12 of 15 , Feb 1, 2005
                            --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                            >
                            > Yah, I can remember manually guiding my fathers scope for 30-60
                            > minutes at a time. I haven't gotten to the point of doing a PEC
                            > correction to the lx90 yet, but that is at least only a 9 minute
                            > guide, once per evening. Too bad it doesn't remember,

                            Um... it DOES remember. All you have to do is PARK the scope
                            at the end of your session to keep the PEC index properly retained.
                            (you can then unclamp and pack it up... your unclamping is
                            -not- affecting the encoder-to-worm relationship).
                            The PEC table itself is in the EEPROM with the rest of your
                            permanent setup information.

                            When you power up next time, it won't offer to Align since it
                            knew you PARKed. But you can certainly menu to Alignment.
                            If you check the PEC controls, you'll find it's already ON.

                            > Just need more practice.

                            ...and a smidge more faith in the Autostar ;-)

                            have fun
                            --dick
                          • foto_phoca
                            Thanks, I guess I assumed too much. I d read several times about how Meade had put PEC into the autostar for the LX90 but becuase the LX90 doesn t have and
                            Message 13 of 15 , Feb 2, 2005
                              Thanks, I guess I assumed too much. I'd read several times about how
                              Meade had put PEC into the autostar for the LX90 but becuase the
                              LX90 "doesn't have and encoder on the RA worm gear, it doesn't
                              remember it's position". Of course no one bothered to say "But if you
                              park the scope every time it accomplished the same goal and your PEC
                              is still good next time you use your scope" :)

                              Last night I did not get an opportunity to test all the alignment
                              suggestions, the one I did try was the one star polar alighment where
                              you start out making sure your OTA is EXACTLY parallel with the forks
                              by pointing it at Polarus and rotating the OTA till polarus no longer
                              moves in the eyepiece. That was a lot easier said that done! It was
                              easy to get it somewhat close in a 26, then 13 mm eyepiece, but with
                              the 9mm the last little bit was the hardest, you almost don't see it
                              inscribing an arc, it just moves up and down or left and right so
                              suddenlty it gets confusing as to which direction you need to be
                              correcting. Just more practice.

                              I did a one star alignment after that, and adjusted the tracking rate
                              to +3 after eyeballing the RA tracking for about 5 minutes. I then
                              left the scope centered on a star for 30 minutes and it moved about
                              1/3 the way to the right and about 1/10 the way to the bottom of the
                              9mm eyepiece. Not too bad.

                              I did several multiple 30 second shots around the sky and the
                              bigggest error seems to be by far the RA PE now. A couple of examples
                              here:

                              http://www.phoca.com/photos/TheRoof/Gallery.cgi?gallery=MorePractice

                              Interestingly, one of them is a little scalloped. I think the scope
                              may have been unbalanced with the camera for that one. Both shots
                              were at prime focus, but are little, full size crops of the entire
                              image. They represent maybe 1/10th the entire FOV so the error looks
                              about 10x worse than in reality (Or like it would look with about
                              750x magnification)

                              Tonight I will try to do a PEC and post some more test shots. I might
                              actually have this thing figured out enough to make a trip to the
                              desert this weekend productive!

                              Larry

                              --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                              >
                              > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                              > >
                              > > Yah, I can remember manually guiding my fathers scope for 30-60
                              > > minutes at a time. I haven't gotten to the point of doing a PEC
                              > > correction to the lx90 yet, but that is at least only a 9 minute
                              > > guide, once per evening. Too bad it doesn't remember,
                              >
                              > Um... it DOES remember. All you have to do is PARK the scope
                              > at the end of your session to keep the PEC index properly retained.
                              > (you can then unclamp and pack it up... your unclamping is
                              > -not- affecting the encoder-to-worm relationship).
                              > The PEC table itself is in the EEPROM with the rest of your
                              > permanent setup information.
                              >
                              > When you power up next time, it won't offer to Align since it
                              > knew you PARKed. But you can certainly menu to Alignment.
                              > If you check the PEC controls, you'll find it's already ON.
                              >
                              > > Just need more practice.
                              >
                              > ...and a smidge more faith in the Autostar ;-)
                              >
                              > have fun
                              > --dick
                            • noddaduma
                              Hi Larry, Oops, I guess I didn t make clear that I just use my good-old 26mm eyepiece for aligning the OTA with the forks. Sorry about that! That is all the
                              Message 14 of 15 , Feb 2, 2005
                                Hi Larry,

                                Oops, I guess I didn't make clear that I just use my good-old 26mm
                                eyepiece for aligning the OTA with the forks. Sorry about that!
                                That is all the accuracy that I've ever needed for that step, and
                                trying to do it at a higher magnification is, as you found out, way
                                too much trouble. However, for the actual "One Star" setup procedure
                                that follows it, I do use my 9mm reticled eyepiece.

                                By the way, where in the desert do you go? Mojave desert?

                                -Jason


                                --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                                >
                                > Thanks, I guess I assumed too much. I'd read several times about
                                how
                                > Meade had put PEC into the autostar for the LX90 but becuase the
                                > LX90 "doesn't have and encoder on the RA worm gear, it doesn't
                                > remember it's position". Of course no one bothered to say "But if
                                you
                                > park the scope every time it accomplished the same goal and your
                                PEC
                                > is still good next time you use your scope" :)
                                >
                                > Last night I did not get an opportunity to test all the alignment
                                > suggestions, the one I did try was the one star polar alighment
                                where
                                > you start out making sure your OTA is EXACTLY parallel with the
                                forks
                                > by pointing it at Polarus and rotating the OTA till polarus no
                                longer
                                > moves in the eyepiece. That was a lot easier said that done! It was
                                > easy to get it somewhat close in a 26, then 13 mm eyepiece, but
                                with
                                > the 9mm the last little bit was the hardest, you almost don't see
                                it
                                > inscribing an arc, it just moves up and down or left and right so
                                > suddenlty it gets confusing as to which direction you need to be
                                > correcting. Just more practice.
                                >
                                > I did a one star alignment after that, and adjusted the tracking
                                rate
                                > to +3 after eyeballing the RA tracking for about 5 minutes. I then
                                > left the scope centered on a star for 30 minutes and it moved about
                                > 1/3 the way to the right and about 1/10 the way to the bottom of
                                the
                                > 9mm eyepiece. Not too bad.
                                >
                                > I did several multiple 30 second shots around the sky and the
                                > bigggest error seems to be by far the RA PE now. A couple of
                                examples
                                > here:
                                >
                                > http://www.phoca.com/photos/TheRoof/Gallery.cgi?gallery=MorePractice
                                >
                                > Interestingly, one of them is a little scalloped. I think the scope
                                > may have been unbalanced with the camera for that one. Both shots
                                > were at prime focus, but are little, full size crops of the entire
                                > image. They represent maybe 1/10th the entire FOV so the error
                                looks
                                > about 10x worse than in reality (Or like it would look with about
                                > 750x magnification)
                                >
                                > Tonight I will try to do a PEC and post some more test shots. I
                                might
                                > actually have this thing figured out enough to make a trip to the
                                > desert this weekend productive!
                                >
                                > Larry
                                >
                                > --- In lx90@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                                > >
                                > > --- In lx90@yahoogroups.com, "foto_phoca" <fstrap@p...> wrote:
                                > > >
                                > > > Yah, I can remember manually guiding my fathers scope for 30-60
                                > > > minutes at a time. I haven't gotten to the point of doing a PEC
                                > > > correction to the lx90 yet, but that is at least only a 9
                                minute
                                > > > guide, once per evening. Too bad it doesn't remember,
                                > >
                                > > Um... it DOES remember. All you have to do is PARK the scope
                                > > at the end of your session to keep the PEC index properly
                                retained.
                                > > (you can then unclamp and pack it up... your unclamping is
                                > > -not- affecting the encoder-to-worm relationship).
                                > > The PEC table itself is in the EEPROM with the rest of your
                                > > permanent setup information.
                                > >
                                > > When you power up next time, it won't offer to Align since it
                                > > knew you PARKed. But you can certainly menu to Alignment.
                                > > If you check the PEC controls, you'll find it's already ON.
                                > >
                                > > > Just need more practice.
                                > >
                                > > ...and a smidge more faith in the Autostar ;-)
                                > >
                                > > have fun
                                > > --dick
                              • foto_phoca
                                Heh, that s ok. As soon as you know what you are doing with something, it becomes very hard to perfectly articulate it to someone that is new. I do tech
                                Message 15 of 15 , Feb 2, 2005
                                  Heh, that's ok.

                                  As soon as you know what you are doing with something, it becomes
                                  very hard to perfectly articulate it to someone that is new. I do
                                  tech support as part of my job and I run into that all the time. It's
                                  impossible to know what the other person does or does not know or
                                  will assume :) I had assumed that you wanted that part of the
                                  alignment to be as accurate as any other. (Though I guess it can only
                                  help if you do)

                                  I camp all over the So Cal deserts, Joshua Tree, Red Rocks, Red Hill,
                                  Borrego etc. One reason I got the scope, might as well have something
                                  do do at night when camping :) But I live in San Diego, so mostly I
                                  go out to Anza-Borrego. I also plan on going up to Palomar mountain
                                  or Cuyamaca as well as Borrego for short overnight trips. It's about
                                  1:15 drive one way from my house to any of them. Jushua Tree is about
                                  1:30 I guess.

                                  This weekend I plan on crashing the Oceanside Photo and Telescope
                                  star party in Anza-Borrego. It seems like a Santa Ana has come up
                                  though, but could be gone by saturday.

                                  Larry

                                  --- In lx90@yahoogroups.com, "noddaduma" <noddaduma@y...> wrote:
                                  >
                                  > Hi Larry,
                                  >
                                  > Oops, I guess I didn't make clear that I just use my good-old 26mm
                                  > eyepiece for aligning the OTA with the forks. Sorry about that!
                                  > That is all the accuracy that I've ever needed for that step, and
                                  > trying to do it at a higher magnification is, as you found out, way
                                  > too much trouble. However, for the actual "One Star" setup
                                  procedure
                                  > that follows it, I do use my 9mm reticled eyepiece.
                                  >
                                  > By the way, where in the desert do you go? Mojave desert?
                                  >
                                  > -Jason
                                  >
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