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RE: [sct-user] Re: collimating indoors????

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  • andy brown
    This months Sky At Night magazine has details (on the cd) of using a laser to collimate an sct. Bit weird as you have to collimate the laser first, then, once
    Message 1 of 20 , Mar 1, 2010
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      This months Sky At Night magazine has details (on the cd) of using a laser to collimate an sct.
      Bit weird as you have to collimate the laser first, then, once you have star tested and collimated the sct you use the laser to find and record an offset mark for future reference.

      I guess that you STILL have to set up the sct using a star(s) then you can return to that position once recorded!!


      Like I said WIERD.


      And.

      To: sct-user@yahoogroups.com
      From: mhholl@...
      Date: Mon, 1 Mar 2010 03:39:48 +0000
      Subject: [sct-user] Re: collimating indoors????
































      --- In sct-user@yahoogroups.com, "tonys" <kclo42112@...> wrote:

      >

      > I remember a collimating lightbox used for collimating indoors,using a led and a pinhole,but dont remember the link,any clues as to where /who wrote about this?



      Tony - the reference below didn't use an LED, it used a lamp, but this may be what you are remembering:



      "How to Build a Portable Artificial Star", Richard Berry

      Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572



      I built one of these using an LED and it works fine.



      HTH



      Mick Hollimon

      28 Feb 10

      7:40 PM PST USA


















      _________________________________________________________________
      Do you have a story that started on Hotmail? Tell us now
      http://clk.atdmt.com/UKM/go/195013117/direct/01/

      [Non-text portions of this message have been removed]
    • Rod Mollise
      Well, maybe not so weird. ;-) This is the same procedure all SCT laser collimation schemes have used up to this point: Collimate the telescope exactly, record
      Message 2 of 20 , Mar 1, 2010
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        Well, maybe not so weird. ;-)

        This is the same procedure all SCT laser collimation schemes have used up to
        this point: Collimate the telescope exactly, record the beam's return
        position, use that to recollimate in the future. Polaris is easier. ;-)


        Peace,
        Rod Mollise
        Rod's new book:
        _Choosing and Using a New CAT_
        Available Now!

        <http://skywatch.brainiac.com/astroland>



        -----Original Message-----
        From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
        Of andy brown
        Sent: Monday, March 01, 2010 3:12 AM
        To: sct-user@yahoogroups.com
        Subject: RE: [sct-user] Re: collimating indoors????


        This months Sky At Night magazine has details (on the cd) of using a laser
        to collimate an sct.
        Bit weird as you have to collimate the laser first, then, once you have star
        tested and collimated the sct you use the laser to find and record an offset
        mark for future reference.

        I guess that you STILL have to set up the sct using a star(s) then you can
        return to that position once recorded!!


        Like I said WIERD.


        And.

        To: sct-user@yahoogroups.com
        From: mhholl@...
        Date: Mon, 1 Mar 2010 03:39:48 +0000
        Subject: [sct-user] Re: collimating indoors????
































        --- In sct-user@yahoogroups.com, "tonys" <kclo42112@...> wrote:

        >

        > I remember a collimating lightbox used for collimating indoors,using a
        led and a pinhole,but dont remember the link,any clues as to where /who
        wrote about this?



        Tony - the reference below didn't use an LED, it used a lamp, but this may
        be what you are remembering:



        "How to Build a Portable Artificial Star", Richard Berry

        Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572



        I built one of these using an LED and it works fine.



        HTH



        Mick Hollimon

        28 Feb 10

        7:40 PM PST USA


















        _________________________________________________________________
        Do you have a story that started on Hotmail? Tell us now
        http://clk.atdmt.com/UKM/go/195013117/direct/01/

        [Non-text portions of this message have been removed]



        ------------------------------------

        Visit the sct-user home page at:



        http://skywatch.brainiac.com/SCThpYahoo! Groups Links
      • girtab
        Yeah, it is not weird at all when you think it through. In a Newt the laser beam reflects off the secondary towards the main mirror which returns it to the
        Message 3 of 20 , Mar 1, 2010
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          Yeah, it is not weird at all when you think it through. In a Newt the laser beam reflects off the secondary towards the main mirror which returns it to the laser via the secondary. If the laser is accurately constructed then adjusting the main mirror to return the beam to the laser's exit aperture does indeed collimate the telescope.

          In an SCT the beam just bounces off the secondary directly back to the laser. It never reaches the main mirror and so the critical alignment between the secondary and primary mirrors is never "sampled" by a traditional laser collimator. IF you first collimate the SCT by traditional means and THEN mark the spot on the face of the laser face where the beam returns IN THEORY you can return the telescope to collimation later on by adjusting the secondary to return the beam to the marked spot. This is an indirect process that may work well enough in practice. Unfortunately it does not give people what they want: a direct collimation that is easier and more accurate than a star collimation in the field.

          Ken

          --- In sct-user@yahoogroups.com, "Rod Mollise" <rmollise@...> wrote:
          >
          > Well, maybe not so weird. ;-)
          >
          > This is the same procedure all SCT laser collimation schemes have used up to
          > this point: Collimate the telescope exactly, record the beam's return
          > position, use that to recollimate in the future. Polaris is easier. ;-)
          >
          >
          > Peace,
          > Rod Mollise
          > Rod's new book:
          > _Choosing and Using a New CAT_
          > Available Now!
          >
          > <http://skywatch.brainiac.com/astroland>
          >
          >
          >
          > -----Original Message-----
          > From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
          > Of andy brown
          > Sent: Monday, March 01, 2010 3:12 AM
          > To: sct-user@yahoogroups.com
          > Subject: RE: [sct-user] Re: collimating indoors????
          >
          >
          > This months Sky At Night magazine has details (on the cd) of using a laser
          > to collimate an sct.
          > Bit weird as you have to collimate the laser first, then, once you have star
          > tested and collimated the sct you use the laser to find and record an offset
          > mark for future reference.
          >
          > I guess that you STILL have to set up the sct using a star(s) then you can
          > return to that position once recorded!!
          >
          >
          > Like I said WIERD.
          >
          >
          > And.
          >
          > To: sct-user@yahoogroups.com
          > From: mhholl@...
          > Date: Mon, 1 Mar 2010 03:39:48 +0000
          > Subject: [sct-user] Re: collimating indoors????
          >
          >
          >
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          > --- In sct-user@yahoogroups.com, "tonys" <kclo42112@> wrote:
          >
          > >
          >
          > > I remember a collimating lightbox used for collimating indoors,using a
          > led and a pinhole,but dont remember the link,any clues as to where /who
          > wrote about this?
          >
          >
          >
          > Tony - the reference below didn't use an LED, it used a lamp, but this may
          > be what you are remembering:
          >
          >
          >
          > "How to Build a Portable Artificial Star", Richard Berry
          >
          > Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572
          >
          >
          >
          > I built one of these using an LED and it works fine.
          >
          >
          >
          > HTH
          >
          >
          >
          > Mick Hollimon
          >
          > 28 Feb 10
          >
          > 7:40 PM PST USA
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > _________________________________________________________________
          > Do you have a story that started on Hotmail? Tell us now
          > http://clk.atdmt.com/UKM/go/195013117/direct/01/
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >
          > ------------------------------------
          >
          > Visit the sct-user home page at:
          >
          >
          >
          > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
          >
        • John Mahony
          Instructions are on Hotech s website, so you must have only been looking at a retailer s site. You could also have searched this group s message archives for
          Message 4 of 20 , Mar 1, 2010
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            Instructions are on Hotech's website, so you must have only been looking at a retailer's site.

            You could also have searched this group's message archives for "SCT laser collimator" and found hundreds, maybe thousands, of messages explaining why lasers aren't very effective in collimating SCTs. It's a common subject.

            -John




            ----- Original Message ----
            > From: tonys <kclo42112@...>
            > To: sct-user@yahoogroups.com
            > Sent: Sun, February 28, 2010 8:21:14 PM
            > Subject: [sct-user] collimating indoors????
            >
            > I remember a collimating lightbox used for collimating indoors,using a led and a
            > pinhole,but dont remember the link,any clues as to where /who wrote about this?
            > I wasted 145 bucksw on a collimating laser last week and am very ticked off,the
            > website only showed it being used and listed it as a hotech crosshair
            > collimator,for sct. when it got here its states I have to fine tune/collimate
            > first using a star and high magnification,then mark the dot on the collimator
            > for"future reference "
            > whjat the heck if I had it collimated that F'n good already why would I need a
            > collomator tool??????,it hasn't been that good seeing in months here in Michigan
            > and they totaly scammed me in the web site,,turns out the video was filmed on a
            > Newt and not an Sct,and there is a seperate set of instructionsand different
            > video witha whole dif link for that tutorial,that they provide AFTER you get the
            > thing sent in the mail.NOT listed anywhere on the website!!!!!! thankfully they
            > apologized and offered me a refund,but only of the purchase price ,so I'm out
            > double shipping.
            >
            >
            >
            > ------------------------------------
            >
            > Visit the sct-user home page at:
            >
            >
            >
            > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
            >
            >
            >
          • John Mahony
            I saw something that looked like that on Hotech s site. But with three precisely aligned lasers in a big aluminum plate, it sounds expensive. $450 according
            Message 5 of 20 , Mar 1, 2010
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              I saw something that looked like that on Hotech's site. But with three precisely aligned lasers in a big aluminum plate, it sounds expensive. $450 according to one source on CN. As someone else on CN said, "I'll keep using Polaris until Polaris starts charging collimation fees".

              -John





              ----- Original Message ----
              > From: Robert Piekiel <piekielrl@...>
              >
              > Withing the last year I saw an article, either in S&T or ATT, that showed a new
              > item coming on the market for collimating CATs in a new way. It was a round
              > disc, the same size as the telescope aperture, with three precision-aligned
              > lasers that fired the beams into the scope. I believe they gave you a retro
              > reflector or cube-corner device that you put into the eyepiece tube. This made
              > the beams come back out the front and back to the big disc. You tweaked and
              > fiddled with the secondary until the three return beams were exactly in line
              > with the source lasers. Very interesting, but I think the price was something
              > like $500.
              > I'd go with an artificial star placed some 20X the focal length away from the
              > scope. They only cost a few dollars to make (LED & pinhole).
              > Best, Bob Piekiel
              >
              > --- On Sun, 2/28/10, tonys wrote:
              >
              > > From: tonys
              > > Subject: [sct-user] collimating indoors????
              > > To: sct-user@yahoogroups.com
              > > Date: Sunday, February 28, 2010, 8:21 PM
              > > I remember a collimating lightbox
              > > used for collimating indoors,using a led and a pinhole,but
              > > dont remember the link,any clues as to where /who wrote
              > > about this? I wasted 145 bucksw on a collimating laser last
              > > week and am very ticked off,the website only showed it being
              > > used and listed it as a hotech crosshair collimator,for sct.
              > > when it got here its states I have to fine tune/collimate
              > > first using a star and high magnification,then mark the dot
              > > on the collimator for"future reference "
              > > whjat the heck if I had it collimated that F'n good already
              > > why would I need a collomator tool??????,it hasn't been that
              > > good seeing in months here in Michigan and they totaly
              > > scammed me in the web site,,turns out the video was filmed
              > > on a Newt and not an Sct,and there is a seperate set of
              > > instructionsand different video witha whole dif link for
              > > that tutorial,that they provide AFTER you get the thing sent
              > > in the mail.NOT listed anywhere on the website!!!!!!
              > > thankfully they apologized and offered me a refund,but only
              > > of the purchase price ,so I'm out double shipping.
              > >
              > >
              > >
              > > ------------------------------------
              > >
              > > Visit the sct-user home page at:
              > >
              > >
              > >
              > > http://skywatch.brainiac.com/SCThpYahoo!
              > > Groups Links
              > >
              > >
              > > sct-user-fullfeatured@yahoogroups.com
              > >
              > >
              > >
              >
              >
              >
              >
              >
              > ------------------------------------
              >
              > Visit the sct-user home page at:
              >
              >
              >
              > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
              >
              >
              >
            • John Mahony
              ... I ve seen at least three other methods, but they could be described as (one each) very inconvenient, or very expensive, or just flat doesn t work. Even
              Message 6 of 20 , Mar 1, 2010
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                ----- Original Message ----

                > From: Rod Mollise <rmollise@...>
                >
                > Well, maybe not so weird. ;-)
                >
                > This is the same procedure all SCT laser collimation schemes have used up to
                > this point: Collimate the telescope exactly, record the beam's return
                > position, use that to recollimate in the future.

                I've seen at least three other methods, but they could be described as (one each) very inconvenient, or very expensive, or just flat doesn't work.

                Even this "basic" method of marking the returning spot on the face of the laser _after_ doing an accurate star collimation is not very accurate. A Mapug meber tested this method several years ago and found that the size of the collimation screw adjustment he needed to make to cause a "noticeable" shift in the returning laser spot was fairly large- what most of us would consider a "crude" adjustment.

                And even then, this method only adjusts one of the three optical components in the scope. If either of the other two shift (such as common mirror flop), your collimation will shift, and you'll need to "re-calibrate" your laser spot.

                > Polaris is easier. ;-)

                Yep, but I think people will be endlessly fascinated with the idea of somehow using a "precision laser" to collimate their SCT. If you're determined to do that, here's how to get the best bang for your buck: go to the local convenience store and spend $5 on a red laser pointer. Bring it home and give it to your kids, and tell them to use it as a cat toy (cats love to chase the spot). That will keep your kids and your cat busy long enough for you to do some research on why laser methods don't work well for SCTs. You'll save at least $100.

                -John



                > -----Original Message-----
                > From: sct-user@yahoogroups.com On Behalf Of andy brown
                >
                > This months Sky At Night magazine has details (on the cd) of using a laser
                > to collimate an sct.
                > Bit weird as you have to collimate the laser first, then, once you have star
                > tested and collimated the sct you use the laser to find and record an offset
                > mark for future reference.
                >
                > I guess that you STILL have to set up the sct using a star(s) then you can
                > return to that position once recorded!!
                >
                >
                > Like I said WIERD.
              • William Dittus
                I have followed many threads on this topic over the years and I myself woould have to agree, FORGET the laser to collimate your SCT. Sadly, just because you
                Message 7 of 20 , Mar 1, 2010
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                  I have followed many threads on this topic over the years and I myself
                  woould have to agree, FORGET the laser to collimate your SCT.

                  Sadly, just because you read something in a magazine does not always make it
                  true. Multiple sources, multiple opinions and last but not least, worst
                  case your own experience.

                  But, if you must buy a laser, buy a green one so you can use it to point out
                  stars to the novices!

                  But, this too is just an opinion.

                  Bill

                  On Mon, Mar 1, 2010 at 10:48 AM, John Mahony <jmmahony@...> wrote:

                  >
                  >
                  > ----- Original Message ----
                  >
                  > > From: Rod Mollise <rmollise@... <rmollise%40bellsouth.net>>
                  > >
                  > > Well, maybe not so weird. ;-)
                  > >
                  > > This is the same procedure all SCT laser collimation schemes have used up
                  > to
                  > > this point: Collimate the telescope exactly, record the beam's return
                  > > position, use that to recollimate in the future.
                  >
                  > I've seen at least three other methods, but they could be described as (one
                  > each) very inconvenient, or very expensive, or just flat doesn't work.
                  >
                  > Even this "basic" method of marking the returning spot on the face of the
                  > laser _after_ doing an accurate star collimation is not very accurate. A
                  > Mapug meber tested this method several years ago and found that the size of
                  > the collimation screw adjustment he needed to make to cause a "noticeable"
                  > shift in the returning laser spot was fairly large- what most of us would
                  > consider a "crude" adjustment.
                  >
                  > And even then, this method only adjusts one of the three optical components
                  > in the scope. If either of the other two shift (such as common mirror flop),
                  > your collimation will shift, and you'll need to "re-calibrate" your laser
                  > spot.
                  >
                  > > Polaris is easier. ;-)
                  >
                  > Yep, but I think people will be endlessly fascinated with the idea of
                  > somehow using a "precision laser" to collimate their SCT. If you're
                  > determined to do that, here's how to get the best bang for your buck: go to
                  > the local convenience store and spend $5 on a red laser pointer. Bring it
                  > home and give it to your kids, and tell them to use it as a cat toy (cats
                  > love to chase the spot). That will keep your kids and your cat busy long
                  > enough for you to do some research on why laser methods don't work well for
                  > SCTs. You'll save at least $100.
                  >
                  > -John
                  >
                  >
                  > > -----Original Message-----
                  > > From: sct-user@yahoogroups.com <sct-user%40yahoogroups.com> On Behalf Of
                  > andy brown
                  > >
                  > > This months Sky At Night magazine has details (on the cd) of using a
                  > laser
                  > > to collimate an sct.
                  > > Bit weird as you have to collimate the laser first, then, once you have
                  > star
                  > > tested and collimated the sct you use the laser to find and record an
                  > offset
                  > > mark for future reference.
                  > >
                  > > I guess that you STILL have to set up the sct using a star(s) then you
                  > can
                  > > return to that position once recorded!!
                  > >
                  > >
                  > > Like I said WIERD.
                  >
                  >
                  >



                  --
                  "Veritas vos liberabit"
                  The Truth Will Set You Free
                  Bill Dittus


                  [Non-text portions of this message have been removed]
                • P T Chambers
                  Hi A few years ago I borrowed a holographic laser that someone had which was proclaimed to be useful in collimating SCTs. I ran a few tests with it and found
                  Message 8 of 20 , Mar 1, 2010
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                    Hi

                    A few years ago I borrowed a "holographic" laser that someone had which
                    was proclaimed to be useful in collimating SCTs.

                    I ran a few tests with it and found the same thing. The adjustments you
                    have to make to see a change in the laser are way too large to be anything
                    close to a precision collimation. If you were in a 60 foot long (or
                    so) room dark enough to see the laser lines at that distance, it might do
                    an acceptable job but the lines themselves would be too fat.

                    Reflected light off of a 2 inch (or so) reflective sphere at about 60 feet
                    does a much better job if you are determined to do a daylight collimation.

                    You still have the problem of the scope not pointing "up" so mirror flop
                    and settling can affect the results however. That issue also applies to
                    the lasers along with their other problems.

                    Star collimation is so easy to do and nature gave us Polaris which is even
                    the right magnitude and doesnt move (detectably). I have not been south
                    of the equator so dont know what stars down there are easy but mag 2 is
                    pretty good.

                    ---------
                    Phil Chambers [ptchamb-at-svpal.org] (S.F. Bay Area - Calif. USA)

                    On Mon, 1 Mar 2010, John Mahony wrote:

                    > ----- Original Message ----
                    >
                    >> From: Rod Mollise <rmollise@...>
                    >>
                    >> Well, maybe not so weird. ;-)
                    >>
                    >> This is the same procedure all SCT laser collimation schemes have used up to
                    >> this point: Collimate the telescope exactly, record the beam's return
                    >> position, use that to recollimate in the future.
                    >
                    > I've seen at least three other methods, but they could be described as (one each) very inconvenient, or very expensive, or just flat doesn't work.
                    >
                    > Even this "basic" method of marking the returning spot on the face of the laser _after_ doing an accurate star collimation is not very accurate. A Mapug meber tested this method several years ago and found that the size of the collimation screw adjustment he needed to make to cause a "noticeable" shift in the returning laser spot was fairly large- what most of us would consider a "crude" adjustment.
                    >
                    > And even then, this method only adjusts one of the three optical components in the scope. If either of the other two shift (such as common mirror flop), your collimation will shift, and you'll need to "re-calibrate" your laser spot.
                    >
                    >> Polaris is easier. ;-)
                    >
                    > Yep, but I think people will be endlessly fascinated with the idea of somehow using a "precision laser" to collimate their SCT. If you're determined to do that, here's how to get the best bang for your buck: go to the local convenience store and spend $5 on a red laser pointer. Bring it home and give it to your kids, and tell them to use it as a cat toy (cats love to chase the spot). That will keep your kids and your cat busy long enough for you to do some research on why laser methods don't work well for SCTs. You'll save at least $100.
                    >
                    > -John
                    >
                    >
                    >
                    >> -----Original Message-----
                    >> From: sct-user@yahoogroups.com On Behalf Of andy brown
                    >>
                    >> This months Sky At Night magazine has details (on the cd) of using a laser
                    >> to collimate an sct.
                    >> Bit weird as you have to collimate the laser first, then, once you have star
                    >> tested and collimated the sct you use the laser to find and record an offset
                    >> mark for future reference.
                    >>
                    >> I guess that you STILL have to set up the sct using a star(s) then you can
                    >> return to that position once recorded!!
                    >>
                    >>
                    >> Like I said WIERD.
                    >
                    >
                    >
                    >
                    >
                    >
                    > ------------------------------------
                    >
                    > Visit the sct-user home page at:
                    >
                    >
                    >
                    > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                    >
                    >
                    >
                    >
                  • Don D'Egidio
                    Try the Hubble Optics Artificial star. I bought one when it was $10 and several in our club are now purchasing them when they saw how good it worked. Just
                    Message 9 of 20 , Mar 1, 2010
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                      Try the Hubble Optics Artificial star. I bought one when it was $10 and several in our club are now
                      purchasing them when they saw how good it worked. Just place it at least 10 focal lengths way (20 is
                      better) for collimating.

                      http://www.hubbleoptics.com/artificial-stars.html

                      Don

                      ----- Original Message -----
                      From: "tonys" <kclo42112@...>
                      To: <sct-user@yahoogroups.com>
                      Sent: Sunday, February 28, 2010 8:21 PM
                      Subject: [sct-user] collimating indoors????


                      > I remember a collimating lightbox used for collimating indoors,using a led and a pinhole,but dont
                      > remember the link,any clues as to where /who wrote about this? I wasted 145 bucksw on a
                      > collimating laser last week and am very ticked off,the website only showed it being used and
                      > listed it as a hotech crosshair collimator,for sct. when it got here its states I have to fine
                      > tune/collimate first using a star and high magnification,then mark the dot on the collimator
                      > for"future reference "
                      > whjat the heck if I had it collimated that F'n good already why would I need a collomator
                      > tool??????,it hasn't been that good seeing in months here in Michigan and they totaly scammed me
                      > in the web site,,turns out the video was filmed on a Newt and not an Sct,and there is a seperate
                      > set of instructionsand different video witha whole dif link for that tutorial,that they provide
                      > AFTER you get the thing sent in the mail.NOT listed anywhere on the website!!!!!! thankfully they
                      > apologized and offered me a refund,but only of the purchase price ,so I'm out double shipping.
                      >
                      >
                      >
                    • John Mahony
                      ... That s a fourth alternate method which I had heard about, but hadn t investigated in any detail, so I left it out of of my mention of at least three
                      Message 10 of 20 , Mar 1, 2010
                      • 0 Attachment
                        ----- Original Message ----

                        > From: P T Chambers <ptchamb@...>
                        >
                        > Hi
                        >
                        > A few years ago I borrowed a "holographic" laser that someone had which
                        > was proclaimed to be useful in collimating SCTs.

                        That's a fourth alternate method which I had heard about, but hadn't investigated in any detail, so I left it out of of my mention of "at least three" alternate methods, below. Glad to hear it's yet another reason to learn how to do something as simple as a standard star collimation.

                        There's a common rule of thumb when adjusting/fine-tuning any piece of high-tech equipment that says to test it in "as close to actual use conditions as possible", to eliminate other variables. The star test does that pretty well. For those who haven't taken my hint to research the various laser/daytime/artificial methods in the group message archives or elsewhere, here are two common "other variables" that affect these methods:

                        As Phil and I both mentioned, mirror flop will affect collimation, so when slewing around the sky you may notice a small change. On most nights, just using Polaris will be good enough. On nights of excellent seeing, if a planet (or close double star, if that's your interest) is well placed, you can fine-tune this by collimating on a medium-bright star near your target. But if you slew down near the horizon, mirror flop can cause severe miscollimation due to dramatic mirror flop. But many daytime/artificial star methods require that you collimate on a target with the scope horizontal, so this collimation can be very wrong for normal astronomical viewing at higher alt angles.

                        Many other methods (including artificial stars) require the scope to be adjusted to focus at a finite distance. That requires moving the primary forward. An SCT has three optical components, but only one is user-adjustable. If the three components are not all perfectly concentric, with a perfectly aligned baffle tube, the primary will move slightly to the side when you change the focus. So collimation won't be the same when you re-adjust the focus to infinity at night.

                        -John


                        > I ran a few tests with it and found the same thing. The adjustments you
                        > have to make to see a change in the laser are way too large to be anything
                        > close to a precision collimation. If you were in a 60 foot long (or
                        > so) room dark enough to see the laser lines at that distance, it might do
                        > an acceptable job but the lines themselves would be too fat.
                        >
                        > Reflected light off of a 2 inch (or so) reflective sphere at about 60 feet
                        > does a much better job if you are determined to do a daylight collimation.
                        >
                        > You still have the problem of the scope not pointing "up" so mirror flop
                        > and settling can affect the results however. That issue also applies to
                        > the lasers along with their other problems.
                        >
                        > Star collimation is so easy to do and nature gave us Polaris which is even
                        > the right magnitude and doesnt move (detectably). I have not been south
                        > of the equator so dont know what stars down there are easy but mag 2 is
                        > pretty good.
                        >
                        > ---------
                        > Phil Chambers [ptchamb-at-svpal.org] (S.F. Bay Area - Calif. USA)
                        >
                        > On Mon, 1 Mar 2010, John Mahony wrote:
                        >
                        > > ----- Original Message ----
                        > >
                        > >> From: Rod Mollise
                        > >>
                        > >> Well, maybe not so weird. ;-)
                        > >>
                        > >> This is the same procedure all SCT laser collimation schemes have used up to
                        > >> this point: Collimate the telescope exactly, record the beam's return
                        > >> position, use that to recollimate in the future.
                        > >
                        > > I've seen at least three other methods, but they could be described as (one
                        > each) very inconvenient, or very expensive, or just flat doesn't work.
                        > >
                        > > Even this "basic" method of marking the returning spot on the face of the
                        > laser _after_ doing an accurate star collimation is not very accurate. A Mapug
                        > meber tested this method several years ago and found that the size of the
                        > collimation screw adjustment he needed to make to cause a "noticeable" shift in
                        > the returning laser spot was fairly large- what most of us would consider a
                        > "crude" adjustment.
                        > >
                        > > And even then, this method only adjusts one of the three optical components in
                        > the scope. If either of the other two shift (such as common mirror flop), your
                        > collimation will shift, and you'll need to "re-calibrate" your laser spot.
                        > >
                        > >> Polaris is easier. ;-)
                        > >
                        > > Yep, but I think people will be endlessly fascinated with the idea of somehow
                        > using a "precision laser" to collimate their SCT. If you're determined to do
                        > that, here's how to get the best bang for your buck: go to the local
                        > convenience store and spend $5 on a red laser pointer. Bring it home and give
                        > it to your kids, and tell them to use it as a cat toy (cats love to chase the
                        > spot). That will keep your kids and your cat busy long enough for you to do
                        > some research on why laser methods don't work well for SCTs. You'll save at
                        > least $100.
                        > >
                        > > -John
                        > >
                        > >
                        > >
                        > >> -----Original Message-----
                        > >> From: sct-user@yahoogroups.com On Behalf Of andy brown
                        > >>
                        > >> This months Sky At Night magazine has details (on the cd) of using a laser
                        > >> to collimate an sct.
                        > >> Bit weird as you have to collimate the laser first, then, once you have star
                        > >> tested and collimated the sct you use the laser to find and record an offset
                        > >> mark for future reference.
                        > >>
                        > >> I guess that you STILL have to set up the sct using a star(s) then you can
                        > >> return to that position once recorded!!
                        > >>
                        > >>
                        > >> Like I said WIERD.
                        > >
                        > >
                        > >
                        > >
                        > >
                        > >
                        > > ------------------------------------
                        > >
                        > > Visit the sct-user home page at:
                        > >
                        > >
                        > >
                        > > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                        > >
                        > >
                        > >
                        > >
                        >
                        >
                        > ------------------------------------
                        >
                        > Visit the sct-user home page at:
                        >
                        >
                        >
                        > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                        >
                        >
                        >
                      • John Mahony
                        That s just another artificial star method. It has various sized stars to fit your scope and distance, but it suffers from the same problems any artificial
                        Message 11 of 20 , Mar 1, 2010
                        • 0 Attachment
                          That's just another artificial star method. It has various sized "stars" to fit your scope and distance, but it suffers from the same problems any artificial star method does.

                          At least the makers are honest enough to admit that a conventional star test is still the "ultimate method to test and collimate your telescopes".

                          -John





                          ----- Original Message ----
                          > From: Don D'Egidio <djd521@...>
                          >
                          > Try the Hubble Optics Artificial star. I bought one when it was $10 and several
                          > in our club are now
                          > purchasing them when they saw how good it worked. Just place it at least 10
                          > focal lengths way (20 is
                          > better) for collimating.
                          >
                          > http://www.hubbleoptics.com/artificial-stars.html
                          >
                          > Don
                          >
                          > ----- Original Message -----
                          > From: "tonys"
                          > To:
                          > Sent: Sunday, February 28, 2010 8:21 PM
                          > Subject: [sct-user] collimating indoors????
                          >
                          >
                          > > I remember a collimating lightbox used for collimating indoors,using a led and
                          > a pinhole,but dont
                          > > remember the link,any clues as to where /who wrote about this? I wasted 145
                          > bucksw on a
                          > > collimating laser last week and am very ticked off,the website only showed it
                          > being used and
                          > > listed it as a hotech crosshair collimator,for sct. when it got here its
                          > states I have to fine
                          > > tune/collimate first using a star and high magnification,then mark the dot on
                          > the collimator
                          > > for"future reference "
                          > > whjat the heck if I had it collimated that F'n good already why would I need a
                          > collomator
                          > > tool??????,it hasn't been that good seeing in months here in Michigan and they
                          > totaly scammed me
                          > > in the web site,,turns out the video was filmed on a Newt and not an Sct,and
                          > there is a seperate
                          > > set of instructionsand different video witha whole dif link for that
                          > tutorial,that they provide
                          > > AFTER you get the thing sent in the mail.NOT listed anywhere on the
                          > website!!!!!! thankfully they
                          > > apologized and offered me a refund,but only of the purchase price ,so I'm out
                          > double shipping.
                          > >
                          > >
                          > >
                          >
                          >
                          >
                          >
                          >
                          > ------------------------------------
                          >
                          > Visit the sct-user home page at:
                          >
                          >
                          >
                          > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                          >
                          >
                          >
                        • Don D'Egidio
                          John, All I can say is it works. When I used it on my C11 I had to wait for a night of almost perfect seeing before I was able to tweak the collimation better.
                          Message 12 of 20 , Mar 1, 2010
                          • 0 Attachment
                            John,

                            All I can say is it works. When I used it on my C11 I had to wait for a night of almost perfect
                            seeing before I was able to tweak the collimation better. I think it was a very well spent $10.

                            Don

                            ----- Original Message -----
                            From: "John Mahony" <jmmahony@...>
                            To: <sct-user@yahoogroups.com>
                            Sent: Monday, March 01, 2010 2:23 PM
                            Subject: Re: [sct-user] collimating indoors????


                            > That's just another artificial star method. It has various sized "stars" to fit your scope and
                            > distance, but it suffers from the same problems any artificial star method does.
                            >
                            > At least the makers are honest enough to admit that a conventional star test is still the
                            > "ultimate method to test and collimate your telescopes".
                            >
                            > -John
                          • tonys
                            yaeh well my scopes on a wheelie bar and only travels like twenty feet from the garage to patio so collomating is never needed untill recently,when I took the
                            Message 13 of 20 , Mar 1, 2010
                            • 0 Attachment
                              yaeh well my scopes on a wheelie bar and only travels like twenty feet from the garage to patio so collomating is never needed untill recently,when I took the whole thing apartt for major cleaning,So I would theoreticaly have that Dang laser tool gathering dust for ever untill needing it ONLY!!!! as a reference mark!!!! stupid !!! not weird,,
                              my opinion anyways .thanks for the replies I will google that artificial star thing, thats exactly what I remember seeing,maybe its in one of the dozens of books I got to ready on cloudy nights ,which are more often than not this winter,looks like I'll be soldering up a battery holder with an led, inside a box.

                              I wonder if ,with todays green and red lasers ...I could shine one on a neighbors garage and collomate off that,.might be bright enough..Hmmmm I love technology and am great with tools so I'll give both a try

                              --- In sct-user@yahoogroups.com, "Rod Mollise" <rmollise@...> wrote:
                              >
                              > Well, maybe not so weird. ;-)
                              >
                              > This is the same procedure all SCT laser collimation schemes have used up to
                              > this point: Collimate the telescope exactly, record the beam's return
                              > position, use that to recollimate in the future. Polaris is easier. ;-)
                              >
                              >
                              > Peace,
                              > Rod Mollise
                              > Rod's new book:
                              > _Choosing and Using a New CAT_
                              > Available Now!
                              >
                              > <http://skywatch.brainiac.com/astroland>
                              >
                              >
                              >
                              > -----Original Message-----
                              > From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
                              > Of andy brown
                              > Sent: Monday, March 01, 2010 3:12 AM
                              > To: sct-user@yahoogroups.com
                              > Subject: RE: [sct-user] Re: collimating indoors????
                              >
                              >
                              > This months Sky At Night magazine has details (on the cd) of using a laser
                              > to collimate an sct.
                              > Bit weird as you have to collimate the laser first, then, once you have star
                              > tested and collimated the sct you use the laser to find and record an offset
                              > mark for future reference.
                              >
                              > I guess that you STILL have to set up the sct using a star(s) then you can
                              > return to that position once recorded!!
                              >
                              >
                              > Like I said WIERD.
                              >
                              >
                              > And.
                              >
                              > To: sct-user@yahoogroups.com
                              > From: mhholl@...
                              > Date: Mon, 1 Mar 2010 03:39:48 +0000
                              > Subject: [sct-user] Re: collimating indoors????
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              > --- In sct-user@yahoogroups.com, "tonys" <kclo42112@> wrote:
                              >
                              > >
                              >
                              > > I remember a collimating lightbox used for collimating indoors,using a
                              > led and a pinhole,but dont remember the link,any clues as to where /who
                              > wrote about this?
                              >
                              >
                              >
                              > Tony - the reference below didn't use an LED, it used a lamp, but this may
                              > be what you are remembering:
                              >
                              >
                              >
                              > "How to Build a Portable Artificial Star", Richard Berry
                              >
                              > Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572
                              >
                              >
                              >
                              > I built one of these using an LED and it works fine.
                              >
                              >
                              >
                              > HTH
                              >
                              >
                              >
                              > Mick Hollimon
                              >
                              > 28 Feb 10
                              >
                              > 7:40 PM PST USA
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              >
                              > _________________________________________________________________
                              > Do you have a story that started on Hotmail? Tell us now
                              > http://clk.atdmt.com/UKM/go/195013117/direct/01/
                              >
                              > [Non-text portions of this message have been removed]
                              >
                              >
                              >
                              > ------------------------------------
                              >
                              > Visit the sct-user home page at:
                              >
                              >
                              >
                              > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                              >
                            • Rod Mollise
                              Assuming the stars are small enough to present nice diffraction patterns, the only drawback is that you probably need to elevate the target. Peace, Rod
                              Message 14 of 20 , Mar 1, 2010
                              • 0 Attachment
                                Assuming the "stars" are small enough to present nice diffraction patterns,
                                the only drawback is that you probably need to elevate the target.


                                Peace,
                                Rod Mollise
                                Rod's new book:
                                _Choosing and Using a New CAT_
                                Available Now!

                                <http://skywatch.brainiac.com/astroland>




                                -----Original Message-----
                                From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
                                Of John Mahony
                                Sent: Monday, March 01, 2010 1:24 PM
                                To: sct-user@yahoogroups.com
                                Subject: Re: [sct-user] collimating indoors????

                                That's just another artificial star method. It has various sized "stars" to
                                fit your scope and distance, but it suffers from the same problems any
                                artificial star method does.

                                At least the makers are honest enough to admit that a conventional star test
                                is still the "ultimate method to test and collimate your telescopes".

                                -John





                                ----- Original Message ----
                                > From: Don D'Egidio <djd521@...>
                                >
                                > Try the Hubble Optics Artificial star. I bought one when it was $10 and
                                several
                                > in our club are now
                                > purchasing them when they saw how good it worked. Just place it at least
                                10
                                > focal lengths way (20 is
                                > better) for collimating.
                                >
                                > http://www.hubbleoptics.com/artificial-stars.html
                                >
                                > Don
                                >
                                > ----- Original Message -----
                                > From: "tonys"
                                > To:
                                > Sent: Sunday, February 28, 2010 8:21 PM
                                > Subject: [sct-user] collimating indoors????
                                >
                                >
                                > > I remember a collimating lightbox used for collimating indoors,using a
                                led and
                                > a pinhole,but dont
                                > > remember the link,any clues as to where /who wrote about this? I wasted
                                145
                                > bucksw on a
                                > > collimating laser last week and am very ticked off,the website only
                                showed it
                                > being used and
                                > > listed it as a hotech crosshair collimator,for sct. when it got here its

                                > states I have to fine
                                > > tune/collimate first using a star and high magnification,then mark the
                                dot on
                                > the collimator
                                > > for"future reference "
                                > > whjat the heck if I had it collimated that F'n good already why would I
                                need a
                                > collomator
                                > > tool??????,it hasn't been that good seeing in months here in Michigan
                                and they
                                > totaly scammed me
                                > > in the web site,,turns out the video was filmed on a Newt and not an
                                Sct,and
                                > there is a seperate
                                > > set of instructionsand different video witha whole dif link for that
                                > tutorial,that they provide
                                > > AFTER you get the thing sent in the mail.NOT listed anywhere on the
                                > website!!!!!! thankfully they
                                > > apologized and offered me a refund,but only of the purchase price ,so
                                I'm out
                                > double shipping.
                                > >
                                > >
                                > >
                                >
                                >
                                >
                                >
                                >
                                > ------------------------------------
                                >
                                > Visit the sct-user home page at:
                                >
                                >
                                >
                                > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                                >
                                >
                                >





                                ------------------------------------

                                Visit the sct-user home page at:



                                http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                              • P T Chambers
                                Hi Use red not green. Also aim it at something round like a 2 inch Christmas ornament. That mitigates the power in the reflection and creates a smaller
                                Message 15 of 20 , Mar 1, 2010
                                • 0 Attachment
                                  Hi
                                  Use red not green. Also aim it at something round like a 2 inch
                                  Christmas ornament. That mitigates the power in the reflection and
                                  creates a smaller point. Cheap laser pointers are not well controlled
                                  and do not have very small "dots" when compared to a star so you need the
                                  "round object reflection".

                                  Your eye is too sensitive to green and the power output on those is
                                  suspect because the "brighter the better". Red ones have less power in
                                  general.

                                  Be careful when looking at laser reflections. Off a small round object,
                                  it is OK but even the lower power lasers when looked at directly can
                                  damage the eye. The so called "safe" power levels are based on "blink
                                  reflex" times and dont count if you force your eye to stay open.

                                  ---------
                                  Phil Chambers [ptchamb-at-svpal.org] (S.F. Bay Area - Calif. USA)

                                  On Mon, 1 Mar 2010, tonys wrote:

                                  > yaeh well my scopes on a wheelie bar and only travels like twenty feet from the garage to patio so collomating is never needed untill recently,when I took the whole thing apartt for major cleaning,So I would theoreticaly have that Dang laser tool gathering dust for ever untill needing it ONLY!!!! as a reference mark!!!! stupid !!! not weird,,
                                  > my opinion anyways .thanks for the replies I will google that artificial star thing, thats exactly what I remember seeing,maybe its in one of the dozens of books I got to ready on cloudy nights ,which are more often than not this winter,looks like I'll be soldering up a battery holder with an led, inside a box.
                                  >
                                  > I wonder if ,with todays green and red lasers ...I could shine one on a neighbors garage and collomate off that,.might be bright enough..Hmmmm I love technology and am great with tools so I'll give both a try
                                  >
                                  > --- In sct-user@yahoogroups.com, "Rod Mollise" <rmollise@...> wrote:
                                  >>
                                  >> Well, maybe not so weird. ;-)
                                  >>
                                  >> This is the same procedure all SCT laser collimation schemes have used up to
                                  >> this point: Collimate the telescope exactly, record the beam's return
                                  >> position, use that to recollimate in the future. Polaris is easier. ;-)
                                  >>
                                  >>
                                  >> Peace,
                                  >> Rod Mollise
                                  >> Rod's new book:
                                  >> _Choosing and Using a New CAT_
                                  >> Available Now!
                                  >>
                                  >> <http://skywatch.brainiac.com/astroland>
                                  >>
                                  >>
                                  >>
                                  >> -----Original Message-----
                                  >> From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
                                  >> Of andy brown
                                  >> Sent: Monday, March 01, 2010 3:12 AM
                                  >> To: sct-user@yahoogroups.com
                                  >> Subject: RE: [sct-user] Re: collimating indoors????
                                  >>
                                  >>
                                  >> This months Sky At Night magazine has details (on the cd) of using a laser
                                  >> to collimate an sct.
                                  >> Bit weird as you have to collimate the laser first, then, once you have star
                                  >> tested and collimated the sct you use the laser to find and record an offset
                                  >> mark for future reference.
                                  >>
                                  >> I guess that you STILL have to set up the sct using a star(s) then you can
                                  >> return to that position once recorded!!
                                  >>
                                  >>
                                  >> Like I said WIERD.
                                  >>
                                  >>
                                  >> And.
                                  >>
                                  >> To: sct-user@yahoogroups.com
                                  >> From: mhholl@...
                                  >> Date: Mon, 1 Mar 2010 03:39:48 +0000
                                  >> Subject: [sct-user] Re: collimating indoors????
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >> --- In sct-user@yahoogroups.com, "tonys" <kclo42112@> wrote:
                                  >>
                                  >>>
                                  >>
                                  >>> I remember a collimating lightbox used for collimating indoors,using a
                                  >> led and a pinhole,but dont remember the link,any clues as to where /who
                                  >> wrote about this?
                                  >>
                                  >>
                                  >>
                                  >> Tony - the reference below didn't use an LED, it used a lamp, but this may
                                  >> be what you are remembering:
                                  >>
                                  >>
                                  >>
                                  >> "How to Build a Portable Artificial Star", Richard Berry
                                  >>
                                  >> Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572
                                  >>
                                  >>
                                  >>
                                  >> I built one of these using an LED and it works fine.
                                  >>
                                  >>
                                  >>
                                  >> HTH
                                  >>
                                  >>
                                  >>
                                  >> Mick Hollimon
                                  >>
                                  >> 28 Feb 10
                                  >>
                                  >> 7:40 PM PST USA
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >>
                                  >> _________________________________________________________________
                                  >> Do you have a story that started on Hotmail? Tell us now
                                  >> http://clk.atdmt.com/UKM/go/195013117/direct/01/
                                  >>
                                  >> [Non-text portions of this message have been removed]
                                  >>
                                  >>
                                  >>
                                  >> ------------------------------------
                                  >>
                                  >> Visit the sct-user home page at:
                                  >>
                                  >>
                                  >>
                                  >> http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                                  >>
                                  >
                                  >
                                  >
                                  >
                                  > ------------------------------------
                                  >
                                  > Visit the sct-user home page at:
                                  >
                                  >
                                  >
                                  > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
                                  >
                                  >
                                  >
                                  >
                                • tonys
                                  Thanks ,I just bought one of those Hubble collimators,sounds truly ingenous and foolproof, I have a HeNe laser that I could use for the chrismas ornament
                                  Message 16 of 20 , Mar 2, 2010
                                  • 0 Attachment
                                    Thanks ,I just bought one of those Hubble collimators,sounds truly ingenous and foolproof,

                                    I have a HeNe laser that I could use for the chrismas ornament trick, I'm kinda nerdy and love gadgets and have had one for twenty+ years just laying around,problem is,it was state of the art twenty years ago at 1 milliwat.my green pointer 25mw and I have several 200mw reds that i can cut foam sheets with

                                    --- In sct-user@yahoogroups.com, P T Chambers <ptchamb@...> wrote:
                                    >
                                    > Hi
                                    > Use red not green. Also aim it at something round like a 2 inch
                                    > Christmas ornament. That mitigates the power in the reflection and
                                    > creates a smaller point. Cheap laser pointers are not well controlled
                                    > and do not have very small "dots" when compared to a star so you need the
                                    > "round object reflection".
                                    >
                                    > Your eye is too sensitive to green and the power output on those is
                                    > suspect because the "brighter the better". Red ones have less power in
                                    > general.
                                    >
                                    > Be careful when looking at laser reflections. Off a small round object,
                                    > it is OK but even the lower power lasers when looked at directly can
                                    > damage the eye. The so called "safe" power levels are based on "blink
                                    > reflex" times and dont count if you force your eye to stay open.
                                    >
                                    > ---------
                                    > Phil Chambers [ptchamb-at-svpal.org] (S.F. Bay Area - Calif. USA)
                                    >
                                    > On Mon, 1 Mar 2010, tonys wrote:
                                    >
                                    > > yaeh well my scopes on a wheelie bar and only travels like twenty feet from the garage to patio so collomating is never needed untill recently,when I took the whole thing apartt for major cleaning,So I would theoreticaly have that Dang laser tool gathering dust for ever untill needing it ONLY!!!! as a reference mark!!!! stupid !!! not weird,,
                                    > > my opinion anyways .thanks for the replies I will google that artificial star thing, thats exactly what I remember seeing,maybe its in one of the dozens of books I got to ready on cloudy nights ,which are more often than not this winter,looks like I'll be soldering up a battery holder with an led, inside a box.
                                    > >
                                    > > I wonder if ,with todays green and red lasers ...I could shine one on a neighbors garage and collomate off that,.might be bright enough..Hmmmm I love technology and am great with tools so I'll give both a try
                                    > >
                                    > > --- In sct-user@yahoogroups.com, "Rod Mollise" <rmollise@> wrote:
                                    > >>
                                    > >> Well, maybe not so weird. ;-)
                                    > >>
                                    > >> This is the same procedure all SCT laser collimation schemes have used up to
                                    > >> this point: Collimate the telescope exactly, record the beam's return
                                    > >> position, use that to recollimate in the future. Polaris is easier. ;-)
                                    > >>
                                    > >>
                                    > >> Peace,
                                    > >> Rod Mollise
                                    > >> Rod's new book:
                                    > >> _Choosing and Using a New CAT_
                                    > >> Available Now!
                                    > >>
                                    > >> <http://skywatch.brainiac.com/astroland>
                                    > >>
                                    > >>
                                    > >>
                                    > >> -----Original Message-----
                                    > >> From: sct-user@yahoogroups.com [mailto:sct-user@yahoogroups.com] On Behalf
                                    > >> Of andy brown
                                    > >> Sent: Monday, March 01, 2010 3:12 AM
                                    > >> To: sct-user@yahoogroups.com
                                    > >> Subject: RE: [sct-user] Re: collimating indoors????
                                    > >>
                                    > >>
                                    > >> This months Sky At Night magazine has details (on the cd) of using a laser
                                    > >> to collimate an sct.
                                    > >> Bit weird as you have to collimate the laser first, then, once you have star
                                    > >> tested and collimated the sct you use the laser to find and record an offset
                                    > >> mark for future reference.
                                    > >>
                                    > >> I guess that you STILL have to set up the sct using a star(s) then you can
                                    > >> return to that position once recorded!!
                                    > >>
                                    > >>
                                    > >> Like I said WIERD.
                                    > >>
                                    > >>
                                    > >> And.
                                    > >>
                                    > >> To: sct-user@yahoogroups.com
                                    > >> From: mhholl@
                                    > >> Date: Mon, 1 Mar 2010 03:39:48 +0000
                                    > >> Subject: [sct-user] Re: collimating indoors????
                                    > >>
                                    > >>
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                                    > >>
                                    > >> --- In sct-user@yahoogroups.com, "tonys" <kclo42112@> wrote:
                                    > >>
                                    > >>>
                                    > >>
                                    > >>> I remember a collimating lightbox used for collimating indoors,using a
                                    > >> led and a pinhole,but dont remember the link,any clues as to where /who
                                    > >> wrote about this?
                                    > >>
                                    > >>
                                    > >>
                                    > >> Tony - the reference below didn't use an LED, it used a lamp, but this may
                                    > >> be what you are remembering:
                                    > >>
                                    > >>
                                    > >>
                                    > >> "How to Build a Portable Artificial Star", Richard Berry
                                    > >>
                                    > >> Gleanings for ATMs, Sky & Telescope, Novemeber, 1992, p. 572
                                    > >>
                                    > >>
                                    > >>
                                    > >> I built one of these using an LED and it works fine.
                                    > >>
                                    > >>
                                    > >>
                                    > >> HTH
                                    > >>
                                    > >>
                                    > >>
                                    > >> Mick Hollimon
                                    > >>
                                    > >> 28 Feb 10
                                    > >>
                                    > >> 7:40 PM PST USA
                                    > >>
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                                    > >>
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