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RE: [ccd-newastro] Compare Mount Setup?

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  • Ron Wodaski
    I have added about 30 new pages to chapter 6, in the section Cutting down noise. The new material covers removing gradients from images, typically from light
    Message 1 of 16 , Mar 2 11:06 PM
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      I have added about 30 new pages to chapter 6, in the section "Cutting down noise." The new material covers removing gradients from images, typically from light pollution. The material added so far covers most of the ways you can deal with gradients, but I have a fair amount of content still to add (using selections directly rather than masks; blurring and subtracting are the two major remaining sub-sections).
       
      However, I think you will find the material posted so far to be helpful even without the additional material. The new content is for subscribers only, and can be viewed on the table of contents page:
       
       
      Note: Since I am writing the last section first, I used letters instead of numbers for the figures, since I don't know what the figure numbers will be yet.

      Ron Wodaski
      The New CCD Astronomy
      http://www.newastro.com  

       

    • Ron Wodaski
      Sorry, I posted this under the wrong subject line, so I am reposting. Ron Wodaski The New CCD Astronomy http://www.newastro.com ... From: Ron Wodaski
      Message 2 of 16 , Mar 2 11:21 PM
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        Sorry, I posted this under the wrong subject line, so I am reposting.
         

        Ron Wodaski
        The New CCD Astronomy
        http://www.newastro.com

        -----Original Message-----
        From: Ron Wodaski [mailto:ronw@...]
        Sent: Friday, March 02, 2001 11:06 PM
        To: ccd-newastro@yahoogroups.com
        Subject: RE: [ccd-newastro] Compare Mount Setup?

        I have added about 30 new pages to chapter 6, in the section "Cutting down noise." The new material covers removing gradients from images, typically from light pollution. The material added so far covers most of the ways you can deal with gradients, but I have a fair amount of content still to add (using selections directly rather than masks; blurring and subtracting are the two major remaining sub-sections).
         
        However, I think you will find the material posted so far to be helpful even without the additional material. The new content is for subscribers only, and can be viewed on the table of contents page:
         
         
        Note: Since I am writing the last section first, I used letters instead of numbers for the figures, since I don't know what the figure numbers will be yet.

        Ron Wodaski
        The New CCD Astronomy
        http://www.newastro.com  

         

      • j.zakariasen@home.com
        Hi Ron, Thank-you so much for the new content!! It could not have come at a better time for me! I have just tried to image M101 but have a severe gradient
        Message 3 of 16 , Mar 4 1:01 PM
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          Hi Ron,

          Thank-you so much for the new content!! It could not have come at a
          better time for me! I have just tried to image M101 but have a
          severe gradient running through it diagonally. Other than trying
          MaximDL flatten command I had no idea what to try. I only recently
          aquired Photoshop and had no idea that it could be used to manually
          compensate for gradients. I'm going to give it a try this afternoon!

          Just wondering if you can tell me a little more about how you mount
          your Light Pollution filter. I use a NGF-S both with my TV101 and my
          C11 and am wondering where and how the filter fits into the image
          train? I took a look at the Borg device but looking at the picture
          it's difficult to tell how it might work. I suppose if I just used
          the standard nosepiece one could screw the filter into it. However,
          I prefer to use the more solid "screw on" collar to attach my ST7 to
          my scope. Your thoughts and suggestions are greatly appreciated!

          Jerry

          --- In ccd-newastro@y..., "Ron Wodaski" <ronw@n...> wrote:
          > Sorry, I posted this under the wrong subject line, so I am
          reposting.
          >
          > Ron Wodaski
          > The New CCD Astronomy
          > http://www.newastro.com
          >
          > -----Original Message-----
          > From: Ron Wodaski [mailto:ronw@n...]
          > Sent: Friday, March 02, 2001 11:06 PM
          > To: ccd-newastro@y...
          > Subject: RE: [ccd-newastro] Compare Mount Setup?
          >
          >
          > I have added about 30 new pages to chapter 6, in the
          section "Cutting down
          > noise." The new material covers removing gradients from images,
          typically
          > from light pollution. The material added so far covers most of the
          ways you
          > can deal with gradients, but I have a fair amount of content still
          to add
          > (using selections directly rather than masks; blurring and
          subtracting are
          > the two major remaining sub-sections).
          >
          > However, I think you will find the material posted so far to be
          helpful
          > even without the additional material. The new content is for
          subscribers
          > only, and can be viewed on the table of contents page:
          >
          > http://www.newastro.com/newastro/book_new/default.asp
          >
          > Note: Since I am writing the last section first, I used letters
          instead of
          > numbers for the figures, since I don't know what the figure numbers
          will be
          > yet.
          > Ron Wodaski
          > The New CCD Astronomy
          > http://www.newastro.com
        • Ron Wodaski
          I m glad the gradient stuff has been helpful. I use the 2 nosepiece to attach my camera to the NGF-S. Can you give me a little more idea of how you are
          Message 4 of 16 , Mar 4 1:23 PM
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            I'm glad the gradient stuff has been helpful.

            I use the 2" nosepiece to attach my camera to the NGF-S. Can you give me a
            little more idea of how you are attaching your camera? I'm not sure what the
            screw-on collar is. Do you have a digital camera to take a picture?

            Ron Wodaski
            The New CCD Astronomy
            http://www.newastro.com

            -----Original Message-----
            From: j.zakariasen@... [mailto:j.zakariasen@...]
            Sent: Sunday, March 04, 2001 1:01 PM
            To: ccd-newastro@yahoogroups.com
            Subject: [ccd-newastro] Re: New content added to book web site: fixing
            gradients


            Hi Ron,

            Thank-you so much for the new content!! It could not have come at a
            better time for me! I have just tried to image M101 but have a
            severe gradient running through it diagonally. Other than trying
            MaximDL flatten command I had no idea what to try. I only recently
            aquired Photoshop and had no idea that it could be used to manually
            compensate for gradients. I'm going to give it a try this afternoon!

            Just wondering if you can tell me a little more about how you mount
            your Light Pollution filter. I use a NGF-S both with my TV101 and my
            C11 and am wondering where and how the filter fits into the image
            train? I took a look at the Borg device but looking at the picture
            it's difficult to tell how it might work. I suppose if I just used
            the standard nosepiece one could screw the filter into it. However,
            I prefer to use the more solid "screw on" collar to attach my ST7 to
            my scope. Your thoughts and suggestions are greatly appreciated!

            Jerry

            --- In ccd-newastro@y..., "Ron Wodaski" <ronw@n...> wrote:
            > Sorry, I posted this under the wrong subject line, so I am
            reposting.
            >
            > Ron Wodaski
            > The New CCD Astronomy
            > http://www.newastro.com
            >
            > -----Original Message-----
            > From: Ron Wodaski [mailto:ronw@n...]
            > Sent: Friday, March 02, 2001 11:06 PM
            > To: ccd-newastro@y...
            > Subject: RE: [ccd-newastro] Compare Mount Setup?
            >
            >
            > I have added about 30 new pages to chapter 6, in the
            section "Cutting down
            > noise." The new material covers removing gradients from images,
            typically
            > from light pollution. The material added so far covers most of the
            ways you
            > can deal with gradients, but I have a fair amount of content still
            to add
            > (using selections directly rather than masks; blurring and
            subtracting are
            > the two major remaining sub-sections).
            >
            > However, I think you will find the material posted so far to be
            helpful
            > even without the additional material. The new content is for
            subscribers
            > only, and can be viewed on the table of contents page:
            >
            > http://www.newastro.com/newastro/book_new/default.asp
            >
            > Note: Since I am writing the last section first, I used letters
            instead of
            > numbers for the figures, since I don't know what the figure numbers
            will be
            > yet.
            > Ron Wodaski
            > The New CCD Astronomy
            > http://www.newastro.com


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          • j.zakariasen@home.com
            Hello All, I recently posted an image called M101 Color Gradient Combo. I also posted the individual channels so that you could see how poor the original
            Message 5 of 16 , Mar 6 5:24 PM
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              Hello All,

              I recently posted an image called M101 Color Gradient Combo. I also
              posted the individual channels so that you could see how poor the
              original data was. Thanks to Ron's latest content on fixing
              gradients I was able to create an LRGB from data that I thought was
              totally useless! Admittedly the LRGB is very poor, but I thought you
              might want to see what could be done even with very crummy data.

              Luminance is 30 minute exposures, Red and Green are 20 minutes Binned
              3x3 and Blue was 40 minutes binned 3x3. All captured with one of the
              old ST7's with an ABG. Scope used was a 4" TV101 refractor. All
              images were done with Track and Accumulate as I still don't have my
              autoguider fixed! Clearly not enough aperature or not enough chip
              sensitivity given my light polluted site. I'm going to upgrade to
              ST7E NABG when I send my camera in for repair. I'm hoping that with
              these modifications my next attempt on this object will be much
              improved. I'm also going to get hold of a Light Pollution Filter and
              see if that helps.

              Jerry
            • j.zakariasen@home.com
              test only please ignore
              Message 6 of 16 , Mar 6 7:48 PM
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                test only please ignore
              • j.zakariasen@home.com
                Hello All, I recent posted some images of M101 to the files section of this group. The LRGB is under M101 Color Gradient Combo. The other 4 posts are the
                Message 7 of 16 , Mar 6 8:19 PM
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                  Hello All,

                  I recent posted some images of M101 to the files section of this
                  group. The LRGB is under M101 Color Gradient Combo. The other 4
                  posts are the individual luminance and R, G, B images. Even though
                  the image of M101 is quite poor,I think it is amazing that I was able
                  to make an image at all given the poor quality of the data.

                  I used Ron's gradient removal techniques to indiviually improve the
                  individual raw images before combining them. With this technique I
                  was able to salvage something from my nights work. Ron has now
                  pointed out to me that I could have done all the gradient correction
                  work only once, directly on the color image, and in 1/4 the time. Oh
                  well, live and learn.

                  I do encourage all those of you with PhotoShop to give this a try.
                  Its the closest thing to magic that I have seen since I saw my
                  first "dark subtract".

                  Image details:

                  Old ST7 ABG and CFW-8 on 4" apo refractor (TV101) from my severely
                  light polluted back yard. Luminance is 1x1 for 30 min. Red and
                  Green were 3x3 binned for 20 minutes and Blue was 3x3 for 40 minutes.

                  All subexposures were 1 minute in duration, done with Track and
                  Accumulate. My self guide function is inoperative at the moment. As
                  you can see nothing, (but especially the color) was done deep
                  enough. This resulted in huge amounts of noise in the color images.
                  I'm afraid that given my light pollution I either need more aperture
                  and/or a more sensitive chip. I am sending my ST7 to SBIG to get the
                  self guide problem fixed and while its there I'm going to get it
                  upgraded to an ST7E NABG. So, hopefully my next attempt with be much
                  improved.

                  Cheers,

                  Jerry
                • Ron Wodaski
                  Actually, although you can do the gradient corrections in the color image, you still might wind up correcting at least three gradients. If the gradient is due
                  Message 8 of 16 , Mar 6 8:41 PM
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                    Actually, although you can do the gradient corrections in the color image,
                    you still might wind up correcting at least three gradients. If the gradient
                    is due to light pollution, it will likely be strongest in the green image,
                    and maybe not present at all in the other color channels. But if the
                    gradient is due to an imperfect flat field (common; flats are a challenge to
                    perfect), you might be able to correct the gradient in the RGB channel, but
                    more often the gradient varies from in the color channels and should be
                    corrected individually for best results.

                    I always encourage patience, as sometimes you might need to correct the
                    gradient in the RGB channel, and then in the R, G, and G channels
                    individually, and compare the results to see which works best! <g>

                    As for the image itself, M101 is a pretty dim object so it is a challenge to
                    get good color or good detail. You have captured a pretty good amount of
                    detail in the arms, including some nice star-forming regions and some HII
                    nebulae. Focus is obviously very good. Longer exposures will give you less
                    noise (graininess), but this is a very good start on color. It's certainly
                    much better than my first attempts at color. <G>

                    Ron Wodaski
                    The New CCD Astronomy
                    http://www.newastro.com

                    -----Original Message-----
                    From: j.zakariasen@... [mailto:j.zakariasen@...]
                    Sent: Tuesday, March 06, 2001 8:19 PM
                    To: ccd-newastro@yahoogroups.com
                    Subject: [ccd-newastro] Re: New content added to book web site: fixing
                    gradients


                    Hello All,

                    I recent posted some images of M101 to the files section of this
                    group. The LRGB is under M101 Color Gradient Combo. The other 4
                    posts are the individual luminance and R, G, B images. Even though
                    the image of M101 is quite poor,I think it is amazing that I was able
                    to make an image at all given the poor quality of the data.

                    I used Ron's gradient removal techniques to indiviually improve the
                    individual raw images before combining them. With this technique I
                    was able to salvage something from my nights work. Ron has now
                    pointed out to me that I could have done all the gradient correction
                    work only once, directly on the color image, and in 1/4 the time. Oh
                    well, live and learn.

                    I do encourage all those of you with PhotoShop to give this a try.
                    Its the closest thing to magic that I have seen since I saw my
                    first "dark subtract".

                    Image details:

                    Old ST7 ABG and CFW-8 on 4" apo refractor (TV101) from my severely
                    light polluted back yard. Luminance is 1x1 for 30 min. Red and
                    Green were 3x3 binned for 20 minutes and Blue was 3x3 for 40 minutes.

                    All subexposures were 1 minute in duration, done with Track and
                    Accumulate. My self guide function is inoperative at the moment. As
                    you can see nothing, (but especially the color) was done deep
                    enough. This resulted in huge amounts of noise in the color images.
                    I'm afraid that given my light pollution I either need more aperture
                    and/or a more sensitive chip. I am sending my ST7 to SBIG to get the
                    self guide problem fixed and while its there I'm going to get it
                    upgraded to an ST7E NABG. So, hopefully my next attempt with be much
                    improved.

                    Cheers,

                    Jerry



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                    ccd-newastro-unsubscribe@egroups.com



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                  • Ron Wodaski
                    March imaging targets (just the new stuff in the east): M13 is rising earlier in the east, and is a great target for beginner s and advanced imagers. For
                    Message 9 of 16 , Mar 7 12:09 PM
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                      March imaging targets (just the new stuff in the east):

                      M13 is rising earlier in the east, and is a great target for beginner's and
                      advanced imagers. For beginners, the better your focus, the better your
                      detail. For processing, digital development or a histogram stretch will
                      reveal literally hundreds of additional stars in the cluster. Several other
                      globulars are also up: M53, M3, both near the Coma-Virgo galaxy cluster.

                      M104, the Sombrero, is both an easy and a challenging target. It's bright
                      enough to capture in short exposures, but long exposures and high
                      magnifications can reveal an amazing amount of very fine detail if you get a
                      really steady night. The core is exceptionally bright, so processing is a
                      challenge and almost demands a histogram stretch.

                      M101 is high enough now to get some really deep exposures. There is no
                      bright core, so try for as long as you can go -- 5 minutes, 10 minutes, 20
                      minutes. Then stack 3, 4, 5 or more to get incredibly good signal to noise.
                      This is getting to be the best time of year for imaging M101.

                      Several other Messier galaxies are also getting to be well positioned: M94,
                      M63 (Sunflower, lots of fine detail), M51 (a classic favorite!), and you
                      might even get M65/M66 in the same field of view. NGC3628 is bright and
                      nearby, making up the "Trio in Leo" that is a spectacular wide-field image.

                      The Virgo Cluster is a one-stop shopping district. There are so many bright
                      Messier and NGC objects here that almost anywhere you point you will find
                      something interesting. There is something for every field of view, from very
                      wide to very long. Some highlights include:

                      - NGC 4568, the Siamese Twins. Interacting galaxies are always a treat to
                      image.
                      - M60, and a bright spiral galaxy (NGC4647) are a very interesting pair.
                      There is considerable detail in the dimmer spiral; can you capture it?
                      - M87 has a well-known jet. An exposure of just the right length should be
                      long enough to show as much jet detail as possible, but not so long that it
                      burns in the core (thus obscuring the jet).
                      - M99, Pinwheel. A spiral with great detail.
                      - M100 is another interesting spiral, bright enough for some nice color work
                      if you take long exposures.
                      - NGC4438 "The Eyes" is in a rich, interesting field of galaxies that also
                      includes the ellipticals M86, and M84. A long exposure could show dozens of
                      galaxies. A 30-minute exposure here could go really deep and show an
                      enormous number of galaxies in a single field. Several interesting spirals
                      around here, too. Wide field imaging ideal.

                      In general, the Coma-Virgo cluster is full of wonder and interesting small
                      galaxies. If you have a long focal length, you can find dozens of
                      interesting galaxies to image here suitable for just about any focal length.

                      Ron Wodaski
                      The New CCD Astronomy
                      http://www.newastro.com
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