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Re: M57 Comments Please

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  • kevinbm13
    Personally, I would scrutinize the collimation. Pehaps the focus as well. SCTs require criticle collimation at very high mags on an IN FOCUS star, noting
    Message 1 of 9 , May 2, 2002
      Personally, I would scrutinize the collimation. Pehaps the focus as
      well. SCTs require criticle collimation at very high mags on an IN
      FOCUS star, noting brightness and uniformity of first diffraction
      ring. I would be looking at 600x+ for a C11. Obviously, there are
      only a few nites a year when that could be done. Perhaps you can do
      300x now on slightly out of focus star. But even thats more than
      most people do. The out of focus diffraction rings need to be
      perfectly symetrical.

      It may have just been crummy seeing as well. Did you use IR
      blocking filter?
      Kevin

      --- In ccd-newastro@y..., "donclearview" <donclearview@y...> wrote:
      > Hello, All
      >
      > New image of M57 taken in mid-April uploaded to the PHOTOS section
      > for comment. My new system is about 4 weeks old, so I've been
      able
      > to get a few images out beyond the usual tasks of getting used to
      the
      > mount, guiding, etc.
      >
      > I was pleased with this image, although I think my color
      saturation
      > is a bit high. However, looking at images of M57 on some of your
      web
      > sites, it appears to me that my stars look somewhat bloated. I
      don't
      > see much evidence of guiding or polar alignment problems. The
      faint
      > stars in the middle of M57 are sharp and the "braided" structure
      in
      > the ring is reasonably sharp for a 50 min image. I am wondering
      if I
      > was a bit out of focus, or if it is just the nature of an SCT,
      with
      > its corrector plate compared to other types. Any comments would
      be
      > most appreciated.
      >
      > Some details:
      > C11 at F10 on MI-250 using a CM10ME at -22C
      > STV on a piggybacked BORG76ED APO at 500 mm for guiding
      > All images binned 2x2 giving ~1 arcsecond/pixel due to ~3.5 FWHM
      > seeing
      > LRGB 50:10:10:16 (2 min subexposures)
      > Shuler filters
      > Aligned in Registrar
      > Mild DDP in Maxim
      > Levels and Curves in PS6.0
      > (yes, I cheated a bit and enhanced the faint background galaxy,
      > IC1296)
      >
      > Don
    • Matt Russell
      Don, I would have to agree, it looks like a potential collimation issue. I ve had several instances where stars on my C-11 look like comets -- and that s
      Message 2 of 9 , May 2, 2002
        Don,

        I would have to agree, it looks like a potential collimation issue. I've
        had several instances where stars on my C-11 look like comets -- and that's
        through the eyepiece. I've run through the collimation routine and it has
        solved the problem. If you don't have them, you may want to install a set
        of Bobs Knobs. They really make collimation a lot easier.

        One thing I also have noticed about my C-11 is it takes FOREVER for it to
        cool down. Do you store it in a dark and cool place? I typically store my
        tube in either the garage or in a dark room in our basement so the tube
        remains relatively cool. Otherwise, I'm looking at about 3-4 hours of
        cool-down time.

        Matt Russell
        http://www.telescopes.cc <http://www.telescopes.cc>


        [Non-text portions of this message have been removed]
      • donclearview
        Thanks, Matt, I m leaning toward focus problems. I don t see any asymmetry in the stars. They are for the most part round and sharp. I ll look at the airy
        Message 3 of 9 , May 3, 2002
          Thanks, Matt,

          I'm leaning toward focus problems. I don't see any asymmetry in the
          stars. They are for the most part round and sharp. I'll look at the
          airy disk pattern tonight to check on collimation. I do not have an
          automatic focuser, as funds were expended for the upgrade, but it's
          on my list.

          By the way, who sells Bobs Knobs?

          Don


          --- In ccd-newastro@y..., Matt Russell <matthewr@e...> wrote:
          > Don,
          >
          > I would have to agree, it looks like a potential collimation
          issue. I've
          > had several instances where stars on my C-11 look like comets --
          and that's
          > through the eyepiece. I've run through the collimation routine and
          it has
          > solved the problem. If you don't have them, you may want to
          install a set
          > of Bobs Knobs. They really make collimation a lot easier.
          >
          > One thing I also have noticed about my C-11 is it takes FOREVER for
          it to
          > cool down. Do you store it in a dark and cool place? I typically
          store my
          > tube in either the garage or in a dark room in our basement so the
          tube
          > remains relatively cool. Otherwise, I'm looking at about 3-4 hours
          of
          > cool-down time.
          >
          > Matt Russell
          > http://www.telescopes.cc <http://www.telescopes.cc>
          >
          >
          > [Non-text portions of this message have been removed]
        • Matt Russell
          Don, You can get a set of Bob s Knobs at http://www.bobsknobs.com . I think they are around $20.00. When you replace the secondary
          Message 4 of 9 , May 3, 2002
            Don,

            You can get a set of Bob's Knobs at http://www.bobsknobs.com
            <http://www.bobsknobs.com> . I think they are around $20.00. When you
            replace the secondary screws with these knobs, a word of caution: only
            remove and replace one screw at a time. Otherwise, you're secondary mirror
            will drop off.

            Your collimation may change from using an eyepiece through a diagonal versus
            directly through the rear of the scope. What I do if I'm checking
            collimation before I image, I slide an eyepiece directly into my Optec
            focuser with no diagonal. The star you are collimating on needs to be
            almost exactly in the center of the eyepiece. Once you adjust one of the
            screws, you need to be sure to re-center the star before evaluating if more
            adjustments need to be made.

            Matt Russell
            http://www.telescopes.cc <http://www.telescopes.cc>


            [Non-text portions of this message have been removed]
          • Bob
            Hi, Don, Maybe I m off target, but I get the messages via email from this group. Certainly NO offense intended. However, bit of a pain to crank up the
            Message 5 of 9 , May 6, 2002
              Hi, Don,

              Maybe I'm off target, but I get the messages via email from this
              group. Certainly NO offense intended. However, bit of a pain to crank up
              the browser, go to Yahoo, search through pages of groups you belong to and
              then to files/photos or whatever. Would, IMHO, be ever so much better if
              you could include the URL in future messages. As it was, I did look--and
              nice image--but it took me nearly three minutes to wade my way there.

              Just a suggestion for those of us who can't/don't have high speed access, Don.

              For those of you who didn't take the time, Don's image is at:
              http://photos.groups.yahoo.com/group/ccd-newastro/vwp?.dir=/&.src=gr&.dnm=M57.jpg&.view=t&.done=http%3a//photos.groups.yahoo.com/group/ccd-newastro/lst%3f%26.dir=/%26.src=gr%26.view=t

              Bob Genung
              Norfolk, UK

              At 20:00 02/05/2002 +0000, you wrote:
              >Hello, All
              >
              >New image of M57 taken in mid-April uploaded to the PHOTOS section
              >for comment. My new system is about 4 weeks old, so I've been able
              >to get a few images out beyond the usual tasks of getting used to the
              >mount, guiding, etc.
              > >>>>>>>>>>>>>>>>>>>>>>>SNIP<<<<<<<<<<<<<<<<<<
              >Don


              [Non-text portions of this message have been removed]
            • donclearview
              Thanks, Bob, I am uploading the few images to the PHOTOS section that I think are of reasonable quality, since I m fairly new to all of this. I m gathering
              Message 6 of 9 , May 6, 2002
                Thanks, Bob,

                I am uploading the few images to the PHOTOS section that I think are
                of reasonable quality, since I'm fairly new to all of this. I'm
                gathering sufficient number of quality images that I will be putting
                together a web site within the next month. That should resolve the
                download problem. Once one gets used to fast connections, we often
                forget what it's like download even 500KB with a 56K modem. Sorry.
                Glad you liked my M57.

                Incidentally, I uploaded M57 to receive comments regarding the size
                of the stars, which look bloated to me in comparison to some images
                posted on various web sites. Some suggested collimantion in my C11,
                but I checked over the weekend and am getting symmetrical airy
                disks. Turned out to be simple focus issues. I can help it out a
                bit on that image with some deconvolution (e.g. RL). I retook an
                hour of luminance this weekend on M57 resulting in much shaper stars
                due to better focusing. I've recently upgraded my entire system as
                of a month ago, and the funds ran out before I could get a
                autofocuser. I could really use it, because I find the focusing of
                the C11 to be "coarse". I don't get mirror flop during 2 hours of
                imaging, but if I don't watch it, I could be off focus.

                Don



                --- In ccd-newastro@y..., Bob <rgenung@m...> wrote:
                > Hi, Don,
                >
                > Maybe I'm off target, but I get the messages via email from this
                > group. Certainly NO offense intended. However, bit of a pain to
                crank up
                > the browser, go to Yahoo, search through pages of groups you belong
                to and
                > then to files/photos or whatever. Would, IMHO, be ever so much
                better if
                > you could include the URL in future messages. As it was, I did
                look--and
                > nice image--but it took me nearly three minutes to wade my way
                there.
                >
                > Just a suggestion for those of us who can't/don't have high speed
                access, Don.
                >
                > For those of you who didn't take the time, Don's image is at:
                > http://photos.groups.yahoo.com/group/ccd-
                newastro/vwp?.dir=/&.src=gr&.dnm=M57.jpg&.view=t&.done=http%
                3a//photos.groups.yahoo.com/group/ccd-newastro/lst%3f%26.dir=/%
                26.src=gr%26.view=t
                >
                > Bob Genung
                > Norfolk, UK
                >
                > At 20:00 02/05/2002 +0000, you wrote:
                > >Hello, All
                > >
                > >New image of M57 taken in mid-April uploaded to the PHOTOS section
                > >for comment. My new system is about 4 weeks old, so I've been able
                > >to get a few images out beyond the usual tasks of getting used to
                the
                > >mount, guiding, etc.
                > > >>>>>>>>>>>>>>>>>>>>>>>SNIP<<<<<<<<<<<<<<<<<<
                > >Don
                >
                >
                > [Non-text portions of this message have been removed]
              • Bob
                Don, Looking closely at the large version of your M57, I d be inclined to believe that the star issue is due to the fact that the tri-color images you
                Message 7 of 9 , May 7, 2002
                  Don,

                  Looking closely at the large version of your M57, I'd be inclined to
                  believe that the star issue is due to the fact that the tri-color images
                  you constructed the composite from are slightly out of alignment. Rather
                  than collimation, this could be a difference in focus between one filter
                  and the next. Did you re-focus when you changed filters? I look at a
                  number of stars, e.g., the bright one to the lower right of the ring in
                  your pic, and it's perfectly round, as are others. But there's color
                  fringing on a number of them that give them a slightly bloated appearance.

                  Obviously others on this list, most especially Ron, may have other
                  ideas. BTW, I personally like the bright color of M57 that you've got, but
                  as you know, color is always a contentious issue--though I personally don't
                  think it should be unless the image is so far off as to make one cringe.

                  Bob Genung

                  At 18:38 06/05/2002 +0000, you wrote:
                  >Thanks, Bob,
                  >
                  >I am uploading the few images to the PHOTOS section that I think are
                  >of reasonable quality, since I'm fairly new to all of this. I'm
                  >gathering sufficient number of quality images that I will be putting
                  >together a web site within the next month. That should resolve the
                  >download problem. Once one gets used to fast connections, we often
                  >forget what it's like download even 500KB with a 56K modem. Sorry.
                  >Glad you liked my M57.
                  >
                  >Incidentally, I uploaded M57 to receive comments regarding the size
                  >of the stars, which look bloated to me in comparison to some images
                  >posted on various web sites. Some suggested collimantion in my C11,
                  >but I checked over the weekend and am getting symmetrical airy
                  >disks. Turned out to be simple focus issues. I can help it out a
                  >bit on that image with some deconvolution (e.g. RL). I retook an
                  >hour of luminance this weekend on M57 resulting in much shaper stars
                  >due to better focusing. I've recently upgraded my entire system as
                  >of a month ago, and the funds ran out before I could get a
                  >autofocuser. I could really use it, because I find the focusing of
                  >the C11 to be "coarse". I don't get mirror flop during 2 hours of
                  >imaging, but if I don't watch it, I could be off focus.
                  >
                  >Don
                  >
                  >
                  >
                  >--- In ccd-newastro@y..., Bob <rgenung@m...> wrote:
                  > > Hi, Don,
                  > >
                  > > Maybe I'm off target, but I get the messages via email from this
                  > > group. Certainly NO offense intended. However, bit of a pain to
                  >crank up
                  > > the browser, go to Yahoo, search through pages of groups you belong
                  >to and
                  > > then to files/photos or whatever. Would, IMHO, be ever so much
                  >better if
                  > > you could include the URL in future messages. As it was, I did
                  >look--and
                  > > nice image--but it took me nearly three minutes to wade my way
                  >there.
                  > >
                  > > Just a suggestion for those of us who can't/don't have high speed
                  >access, Don.
                  > >
                  > > For those of you who didn't take the time, Don's image is at:
                  > >
                  > <http://photos.groups.yahoo.com/group/ccd->http://photos.groups.yahoo.com/group/ccd-
                  >newastro/vwp?.dir=/&.src=gr&.dnm=M57.jpg&.view=t&.done=http%
                  >3a//photos.groups.yahoo.com/group/ccd-newastro/lst%3f%26.dir=/%
                  >26.src=gr%26.view=t
                  > >
                  > > Bob Genung
                  > > Norfolk, UK
                  > >
                  > > At 20:00 02/05/2002 +0000, you wrote:
                  > > >Hello, All
                  > > >
                  > > >New image of M57 taken in mid-April uploaded to the PHOTOS section
                  > > >for comment. My new system is about 4 weeks old, so I've been able
                  > > >to get a few images out beyond the usual tasks of getting used to
                  >the
                  > > >mount, guiding, etc.
                  > > > >>>>>>>>>>>>>>>>>>>>>>>SNIP<<<<<<<<<<<<<<<<<<
                  > > >Don
                  > >
                  > >
                  > > [Non-text portions of this message have been removed]
                  >
                  >
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                  [Non-text portions of this message have been removed]
                • donclearview
                  Bob, been on vacation. Thanks for your comments on my M57. You re correct. There is fringing due to registration issues. I purchased Registrar recently and
                  Message 8 of 9 , May 12, 2002
                    Bob, been on vacation. Thanks for your comments on my M57. You're
                    correct. There is fringing due to registration issues. I purchased
                    Registrar recently and will have a go at this. Also, the problem
                    with "bloated" stars mentioned earlier was due to poor focus. I took
                    another hour of liminance last weekend (1 week later) and the stars
                    are very sharp. Will re-do the whole image shortly. I find that
                    manual focusing of the C11 is quite difficult and not "solid". I
                    really need a focuser, which must await amassing of additonal funds
                    and deciding among the Optek, JMI and FLI. Not an obvious choice
                    among back focus/size, temperature correction and price! Thanks for
                    your comments. I have about 16 hours of images to process over the
                    past 2 weekends, which should keep me busy when the moon's up.

                    Don




                    --- In ccd-newastro@y..., Bob <rgenung@m...> wrote:
                    > Don,
                    >
                    > Looking closely at the large version of your M57, I'd be inclined
                    to
                    > believe that the star issue is due to the fact that the tri-color
                    images
                    > you constructed the composite from are slightly out of alignment.
                    Rather
                    > than collimation, this could be a difference in focus between one
                    filter
                    > and the next. Did you re-focus when you changed filters? I look
                    at a
                    > number of stars, e.g., the bright one to the lower right of the
                    ring in
                    > your pic, and it's perfectly round, as are others. But there's
                    color
                    > fringing on a number of them that give them a slightly bloated
                    appearance.
                    >
                    > Obviously others on this list, most especially Ron, may have other
                    > ideas. BTW, I personally like the bright color of M57 that you've
                    got, but
                    > as you know, color is always a contentious issue--though I
                    personally don't
                    > think it should be unless the image is so far off as to make one
                    cringe.
                    >
                    > Bob Genung
                    >
                    > At 18:38 06/05/2002 +0000, you wrote:
                    > >Thanks, Bob,
                    > >
                    > >I am uploading the few images to the PHOTOS section that I think
                    are
                    > >of reasonable quality, since I'm fairly new to all of this. I'm
                    > >gathering sufficient number of quality images that I will be
                    putting
                    > >together a web site within the next month. That should resolve the
                    > >download problem. Once one gets used to fast connections, we often
                    > >forget what it's like download even 500KB with a 56K modem. Sorry.
                    > >Glad you liked my M57.
                    > >
                    > >Incidentally, I uploaded M57 to receive comments regarding the size
                    > >of the stars, which look bloated to me in comparison to some images
                    > >posted on various web sites. Some suggested collimantion in my
                    C11,
                    > >but I checked over the weekend and am getting symmetrical airy
                    > >disks. Turned out to be simple focus issues. I can help it out a
                    > >bit on that image with some deconvolution (e.g. RL). I retook an
                    > >hour of luminance this weekend on M57 resulting in much shaper
                    stars
                    > >due to better focusing. I've recently upgraded my entire system as
                    > >of a month ago, and the funds ran out before I could get a
                    > >autofocuser. I could really use it, because I find the focusing of
                    > >the C11 to be "coarse". I don't get mirror flop during 2 hours of
                    > >imaging, but if I don't watch it, I could be off focus.
                    > >
                    > >Don
                    > >
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