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Re: collimation w/26mm EP only?

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  • Leor Zolman
    3:15am EST: Prayer answered: skies clear. Mr. Cassini & I are now much better acquainted, thank you very much. Looks like three moons, perhaps more if they
    Message 1 of 20 , Nov 1, 2003
      3:15am EST: Prayer answered: skies clear. Mr. Cassini & I are now much
      better acquainted, thank you very much. Looks like three moons, perhaps
      more if they can be really far away. I'm too fried to go check charts/S&T
      for moon data.

      If I'm willing to let my 9am tennis game suffer a bit more, I'll give
      Jupiter a few more minutes to clear the trees.

      Upon responding to a particularly resonant observing report on SAA from a
      fellow Mass. resident, and e-chatting about collimation, I've been invited
      to an upcoming observing session with his group and their resident
      collimation expert. If my wife and I can get this far by ourselves, I find
      it hard to imagine how good Saturn's gonna look after *that* guy's had his
      way with my scope... ;-}
      -leor


      [Non-text portions of this message have been removed]
    • Ted Kurkowski
      ... the upper ... everything ... John s right, and so, Leor, you ll want to know if the Jet Stream is overhead at your location. One of a number of web sites
      Message 2 of 20 , Nov 1, 2003
        --- In sct-user@yahoogroups.com, "John Mahony" <jmmahony@h...> wrote:

        > And keep in
        > mind that on very bad nights, you can get high-speed turbulence in
        the upper
        > atmosphere, where the rippling is so fast you don't even see it-
        everything
        > just looks fuzzy.
        >
        > -John

        John's right, and so, Leor, you'll want to know if the Jet Stream is
        overhead at your location. One of a number of web sites for that is:

        www.weatherimages.org/data/imag192.html

        Also, Atilla Danko's Clear Sky Clock does a good job of predicting the
        viewing conditions for the upcoming night. Go to:

        www.esabogal.com/~cleardar/

        and find a site near where you observe. That predictive model does
        include the Jet Stream position as well as a _lot_ of other variables.

        Ted

        An SCT Site for Beginners -
        http://home.earthlink.net/~tkurkowski/
      • Leor Zolman
        ... Nice page! Before I looked on it, I just Googled for jet stream maps. When I found this one, I thought it odd that the Stream would just end as it hit the
        Message 3 of 20 , Nov 1, 2003
          At 12:29 PM 11/1/2003 +0000, you wrote:

          >--- In sct-user@yahoogroups.com, "John Mahony" <jmmahony@h...> wrote:
          >
          > > And keep in
          > > mind that on very bad nights, you can get high-speed turbulence in
          >the upper
          > > atmosphere, where the rippling is so fast you don't even see it-
          >everything
          > > just looks fuzzy.
          > >
          > > -John
          >
          >John's right, and so, Leor, you'll want to know if the Jet Stream is
          >overhead at your location. One of a number of web sites for that is:
          >
          >www.weatherimages.org/data/imag192.html

          Nice page! Before I looked on it, I just Googled for jet stream maps. When
          I found this one, I thought it odd that the Stream would just end as it hit
          the US:

          http://virga.sfsu.edu/gif/jetstream_norhem_00.gif

          The same site's closeup of the US shows no Jet Stream at all. Then I went
          and looked at the site you gave me above, and saw that at 6am this morning
          (3 hours after my last look at Saturn; Jupiter got cancelled due to a new
          bank of clouds), the Jet Stream was in fact right up there blowing my hair
          into disarray. So, cool! That means tonight the seeing can only improve! ;-)


          >Also, Atilla Danko's Clear Sky Clock does a good job of predicting the
          >viewing conditions for the upcoming night. Go to:
          >
          >www.esabogal.com/~cleardar/
          >
          >and find a site near where you observe. That predictive model does
          >include the Jet Stream position as well as a _lot_ of other variables.

          I've been using the Veasey Memorial Park Clear Sky Clock provided by NSAAC.
          But mostly I've been relying on Intellicast satellite and radar maps. I'm
          now adding that Jet Stream page to my repertoire.

          Just now I discovered the "Stargaze" section of the Intellicast site's
          "Planner" menu! Unfortunately, it seems to be a bit broken. After I was
          presented with a choice of pages and selected "sky watch" (or "viewing
          conditions", I don't know what the original link was labeled), now that's
          the only page I can ever get to any more. Does this happen for anyone else?
          -leor


          >Ted
          >
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        • starhopper44
          Hi Leor - & welcome aboard this mad-train! *L* Am gonna go ahead & jump in at this point to respond, before reading the remainder of the threads, and hope I
          Message 4 of 20 , Nov 1, 2003
            Hi Leor - & welcome aboard this mad-train! *L*

            Am gonna go ahead & jump in at this point to respond, before reading
            the remainder of the threads, and hope I don't re-cover beaten paths.
            One of (IMO) the first hurdles to get over is the actual act of
            learning to collimate -- learning by doing. Once 'the art' is
            acquired, what first seemed an eggshell path over a bottomless lava
            pit becomes a breeze, & you can almost do it while reading the latest
            S&T! ~8)

            No harm in using what you've already got to get started on the
            learning curve....and as someone said already, keywords are slow, &
            gentle 'tweaks' on the screws. I would add in there: observation &
            analysis of results of each tweak (figure out 'which way to go' to get
            to correct point). Another 'tip' I'll toss in - carefully re-center
            your star after each tweak, & don't forget that step.

            At any rate your new EP 'kit' will eventually arrive, and by then
            you'll hopefully be at a stage where all you'll have remaining is a
            better selection of 'tools' to do your collimation with! *yay* Fact
            is, as I think you'll find, some scopes hold alignment amazingly well,
            while others need tweaking every session sometimes more! Even if
            yours is one of the 'good ones', nonetheless it still needs frequent
            checking. After awhile your scope's character will be apparent, and
            you'll even get to a point when you'll know it might need a tweak
            merely by the image it's giving.

            Clear, still, & dark dark skies!
            ~Star*Hopper
            <><><><><><><><><><><>



            --- In sct-user@yahoogroups.com, Leor Zolman <leor@b...> wrote:
            > At 12:50 AM 11/1/2003 +0000, you wrote:
            >
            > >First congratulations on your scope! You should be very happy with
            > >it.
            >
            > Thanks! I've been ecstatic. I'm also a computer geek, so the go-to
            features
            > are a blast (in
            > my profession, "goto" is usually "considered harmful", and some in
            > astronomy would undoubtedly
            > extend that characterization to telescopes. But the fact is, my
            Celestron
            > Firscope 114 sat and rotted,
            > while the LX200 is well on its way to getting worn out ;-)
            >
            >
            > >Now to collimation. I have a C8 so I have something similar to what
            > >you have. At 160x Saturn should be fairly crisp even with average
            > >seeing - it is for me. In fact, I can clearly see the division all
            > >around even at 226x with gradations on the globe on average to good
            > >nights. To get this performance you need to be well collimated. But
            > >to collimate right you need to go through at least two steps.
            >
            > I just read, and am replying to this post, while I wait for my wife
            to get
            > freed up from what she is doing so that she can look into the EP
            while I
            > turn the collimation screws. I trust her ability to detect what is
            centered
            > more than my own (funny how astronomy imitates life...)
            >
            >
            > >The first (centering the doughnut hole) is a necessary but not
            > >sufficient step. This just gets you in the ballpark. You will need
            > >to use around 250x to perform a fine out-of-focus test (step 2).
            > >Here's how to tell if seeing and or collimation is the problem.
            Find
            > >and lock onto a bright star. Slightly put it out of focus until you
            > >see around 5 rings. If they are perfectly centered, with a dot in
            > >the middle, you are reasonably well collimated. Now look at how the
            > >rings behave over time. Do you see ripples running through them or
            > >are they perfectly steady? The former indicated seeing problems,
            the
            > >latter excellent seeing. If the rings are skewed to a side you need
            > >to collimate.
            >
            > My big problem is limited choice of magnification. I have the
            following to
            > choose from: 80x, 160x, 400x (my sole 26mm EP, 2X Barlow, 5X
            Barlow).
            > That's IT. The doughnut hole is pretty well centered already, as far
            as I
            > can tell, so for now it's all going to boil down to those concentric
            > wanna-be circles. I see them clearly being off-center at 160x. So I
            have
            > that to address.
            >
            >
            > >However, as Legault points out, this is not the end, especially if
            > >you want to get the best out of your SCT. For this you need about
            > >500-600X. Focus the star and look for the diffraction rings around
            > >the Airy disk. If this is again perfectly centered you are perfect.
            > >If it's skewed, or broken on a side, you can tweak it again.
            >
            > If I see good results from equalizing the rings, I may attempt phase
            3.
            >
            >
            > >For planetary viewing it is CRITICAL that your scope is well
            > >collimated - even slight miscollimation can make it perform worse
            > >than a 3-4" refractor (on low contrast objects like the surface of
            > >Jupiter/Saturn)!
            > >
            > >Good luck, and ENJOY!!
            >
            > Okay, thanks! I appreciate getting information that's in agreement
            from so
            > many sources (Rod's book, Thierry's page, your post). The thing
            about
            > ripples being a measure of seeing is great, I don't recall seeing
            that before.
            >
            > I think I'm confident enough now that my prior fear of committing
            negligent
            > scope-icide has more-or-less abated...
            > -leor
            >
            >
            > ====================================================================
            > Leor Zolman leor@b...
            > BD Software www.bdsoft.com
            > 74 Marblehead St. North Reading, MA 01864
            > Voice: 978-664-9856 FAX: 978-664-4178
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          • starhopper44
            ... the ... variables. ... ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Ted - (& all) - As far as I know, Atilla s got his old domain problem resolved -- my
            Message 5 of 20 , Nov 1, 2003
              --- In sct-user@yahoogroups.com, "Ted Kurkowski" <tkurkowski@e...>
              wrote:
              > --- In sct-user@yahoogroups.com, "John Mahony" <jmmahony@h...>
              wrote:
              >
              > > And keep in
              > > mind that on very bad nights, you can get high-speed turbulence in
              > the upper
              > > atmosphere, where the rippling is so fast you don't even see it-
              > everything
              > > just looks fuzzy.
              > >
              > > -John
              >
              > John's right, and so, Leor, you'll want to know if the Jet Stream is
              > overhead at your location. One of a number of web sites for that
              is:
              >
              > www.weatherimages.org/data/imag192.html
              >
              > Also, Atilla Danko's Clear Sky Clock does a good job of predicting
              the
              > viewing conditions for the upcoming night. Go to:
              >
              > www.esabogal.com/~cleardar/
              >
              > and find a site near where you observe. That predictive model does
              > include the Jet Stream position as well as a _lot_ of other
              variables.
              >
              > Ted
              >
              > An SCT Site for Beginners -
              > http://home.earthlink.net/~tkurkowski/

              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
              Ted - (& all) - As far as I know, Atilla's got his old domain problem
              resolved -- my clock's back up & working as of about Friday or so.

              Leor, try this link -- should be index page for all the CSC's in Mass:
              http://cleardarksky.com/csk/prov/Massachusetts_clocks.shtml

              & pick a/some nearby one(s) to use. I think I remember him saying each
              location is good for about a 20-mile radius. It'll also show you some
              nearby groups you might wanna get in touch with!

              Clear'ns
              ~S*H
            • Leor Zolman
              ... Yah, I just have to watch my speed ... ... Good thing I just bought that Ray-O-Vac head light, cause otherwise I d probably run out of hands to collimate
              Message 6 of 20 , Nov 1, 2003
                At 04:40 PM 11/1/2003 +0000, you wrote:

                >Hi Leor - & welcome aboard this mad-train! *L*

                Yah, I just have to "watch my speed"...

                >Am gonna go ahead & jump in at this point to respond, before reading
                >the remainder of the threads, and hope I don't re-cover beaten paths.
                >One of (IMO) the first hurdles to get over is the actual act of
                >learning to collimate -- learning by doing. Once 'the art' is
                >acquired, what first seemed an eggshell path over a bottomless lava
                >pit becomes a breeze, & you can almost do it while reading the latest
                >S&T! ~8)

                Good thing I just bought that Ray-O-Vac head light, 'cause otherwise I'd
                probably run out of hands to collimate and keep the S&T in a comfortable
                reading position ;-)


                >No harm in using what you've already got to get started on the
                >learning curve....and as someone said already, keywords are slow, &
                >gentle 'tweaks' on the screws. I would add in there: observation &
                >analysis of results of each tweak (figure out 'which way to go' to get
                >to correct point).

                That was the most worrisome part-- how many tweaks was it gonna take before
                we were truly confident about the effect we were having on the mirror? As
                it turned out, not too many. *sigh of relief*.

                > Another 'tip' I'll toss in - carefully re-center
                >your star after each tweak, & don't forget that step.

                Yup, read it and was prepared for it. One place I was reading actually said
                "if it gets off center, don't worry about it too much", but I couldn't see
                any drawback to slewing the scope back to center. Futzing with the focus
                knob, however, was something I decided early on I would do an absolute
                minimum of, to avoid sabotaging my tweaking of the secondary by shifting
                the primary's position.

                >
                >
                >At any rate your new EP 'kit' will eventually arrive, and by then
                >you'll hopefully be at a stage where all you'll have remaining is a
                >better selection of 'tools' to do your collimation with! *yay*

                yeah, it'll feel a lot like it did when I finally saw an aurora the other
                night ;-)

                > Fact
                >is, as I think you'll find, some scopes hold alignment amazingly well,
                >while others need tweaking every session sometimes more! Even if
                >yours is one of the 'good ones', nonetheless it still needs frequent
                >checking. After awhile your scope's character will be apparent, and
                >you'll even get to a point when you'll know it might need a tweak
                >merely by the image it's giving.

                And fortunately, it is easy enough to check collimation by defocusing.


                >Clear, still, & dark dark skies!

                Last night, staying up to see Saturn after collimation, I was *amazed* how
                dry everything was staying. That has got to be the very first night in the
                past two and a half months that I've had the LX200 out that stuff wasn't
                getting all dewy. At 3am, the aluminum equipment case was bone-dry! The S&T
                out on the table was bone dry! How bizarre! (Those of you down in the
                SouthWest can start feeling sorry for me now...)
                -leor


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              • John Mahony
                Don t get your expectations too high. Collimating an SCT is easy enough that even a beginner can usually do it well enough that on most nights the seeing
                Message 7 of 20 , Nov 1, 2003
                  Don't get your expectations too high. Collimating an SCT is easy enough
                  that even a beginner can usually do it well enough that on most nights the
                  seeing quality will be the limiting factor. Fine tuning helps when the
                  seeing is very good, but the adjustment is small enough that just slewing
                  around the sky (or focusing, since it sounds like your scope has a fair
                  amount of image shift when focusing) can thow it off.
                  -John

                  >From: Leor Zolman <leor@...>
                  >
                  >Upon responding to a particularly resonant observing report on SAA from a
                  >fellow Mass. resident, and e-chatting about collimation, I've been invited
                  >to an upcoming observing session with his group and their resident
                  >collimation expert. If my wife and I can get this far by ourselves, I find
                  >it hard to imagine how good Saturn's gonna look after *that* guy's had his
                  >way with my scope... ;-}
                  > -leor

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                • Leor Zolman
                  ... I ve got the Peterson EZ Focus kit ready to rock n roll, but I try to limit the number of potentially destructive procedures I do to the scope to one per
                  Message 8 of 20 , Nov 1, 2003
                    At 11:43 PM 11/1/2003 -0500, you wrote:

                    >Don't get your expectations too high. Collimating an SCT is easy enough
                    >that even a beginner can usually do it well enough that on most nights the
                    >seeing quality will be the limiting factor. Fine tuning helps when the
                    >seeing is very good, but the adjustment is small enough that just slewing
                    >around the sky (or focusing, since it sounds like your scope has a fair
                    >amount of image shift when focusing) can thow it off.

                    I've got the Peterson EZ Focus kit ready to rock n' roll, but I try to
                    limit the number of potentially destructive procedures I do to the scope to
                    one per every few days ;-)
                    -leor


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                  • John Mahony
                    The EZ focus kit does not help this problem. It cures backlash, and generally improves the smoothness of the knob motion, but image shift is caused by the
                    Message 9 of 20 , Nov 2, 2003
                      The EZ focus kit does not help this problem. It cures backlash, and
                      generally improves the smoothness of the knob motion, but image shift is
                      caused by the mirror wobbling on the center baffle tube as the focus rod
                      moves it forward or backwards. The focus knob and EZ focus kit has nothing
                      to do with this.
                      -John


                      >From: Leor Zolman <leor@...>
                      >
                      >At 11:43 PM 11/1/2003 -0500, you wrote:
                      >
                      > >Don't get your expectations too high. Collimating an SCT is easy enough
                      > >that even a beginner can usually do it well enough that on most nights
                      >the
                      > >seeing quality will be the limiting factor. Fine tuning helps when the
                      > >seeing is very good, but the adjustment is small enough that just slewing
                      > >around the sky (or focusing, since it sounds like your scope has a fair
                      > >amount of image shift when focusing) can thow it off.
                      >
                      >I've got the Peterson EZ Focus kit ready to rock n' roll, but I try to
                      >limit the number of potentially destructive procedures I do to the scope to
                      >one per every few days ;-)
                      > -leor

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                    • Leor Zolman
                      ... Ah, indeed. Somewhere I got it into my head that reducing image shift is the EZ Focus s major purpose, but after reading the info on Peterson s web site
                      Message 10 of 20 , Nov 2, 2003
                        At 06:49 AM 11/2/2003 -0500, you wrote:

                        >The EZ focus kit does not help this problem. It cures backlash, and
                        >generally improves the smoothness of the knob motion, but image shift is
                        >caused by the mirror wobbling on the center baffle tube as the focus rod
                        >moves it forward or backwards. The focus knob and EZ focus kit has nothing
                        >to do with this.
                        >-John

                        Ah, indeed. Somewhere I got it into my head that reducing image shift is
                        the EZ Focus's major purpose, but after reading the info on Peterson's web
                        site again I can see that I was out in left field. I'll try just running
                        the focus travel end-to-end a few times and see if that helps with the shift.

                        On the bright side, from customer feedback shown on the site it sounds like
                        installation of the EZ Focus will be fairly easy, and, if I'm successful
                        (when I expressed my concerns to him directly, Pete wrote back to me "Don't
                        worry, we won't let you fail!"), it ought to bring out the best in the
                        scope and complement the collimation...

                        Here's the dumb filter question: When using a Barlow, do folks typically
                        put filters on the Barlow or on the EP?
                        -leor



                        > >From: Leor Zolman <leor@...>
                        > >
                        > >At 11:43 PM 11/1/2003 -0500, you wrote:
                        > >
                        > > >Don't get your expectations too high. Collimating an SCT is easy enough
                        > > >that even a beginner can usually do it well enough that on most nights
                        > >the
                        > > >seeing quality will be the limiting factor. Fine tuning helps when the
                        > > >seeing is very good, but the adjustment is small enough that just slewing
                        > > >around the sky (or focusing, since it sounds like your scope has a fair
                        > > >amount of image shift when focusing) can thow it off.
                        > >
                        > >I've got the Peterson EZ Focus kit ready to rock n' roll, but I try to
                        > >limit the number of potentially destructive procedures I do to the scope to
                        > >one per every few days ;-)
                        > > -leor
                        >
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                        Leor Zolman leor@...
                        BD Software www.bdsoft.com
                        74 Marblehead St. North Reading, MA 01864
                        Voice: 978-664-9856 FAX: 978-664-4178

                        Comeau / Intel / CodeWarrior / gcc / Borland / Visual C++ users:
                        Download BD Software's FREE STL Error Message Decryptor at
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                      • starhopper44
                        ... typically ... ^^^^^^^^^^^^^^^^^^^^^^^^ Answering indirectly - where the filter is in the optical train doesn t affect what it does . The ┬┐obvious?
                        Message 11 of 20 , Nov 2, 2003
                          --- In sct-user@yahoogroups.com, Leor Zolman <leor@b...> wrote:
                          >.......filter question: When using a Barlow, do folks
                          typically
                          > put filters on the Barlow or on the EP?
                          > -leor
                          ^^^^^^^^^^^^^^^^^^^^^^^^
                          Answering indirectly - 'where' the filter is in the optical train
                          doesn't affect what it 'does'. The ┬┐obvious? implication is that by
                          installing it on the Barlow, you can freely change EPs w/o having to
                          remove/re-install the filter in them each swap.
                          ~S*H
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