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Astrodon 6nm Ha filter + ST10XME = low signal!?!

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  • vfregembal
    Hi, I am using an Astrodon Ha 6nm filter with my ST10XME. However, after running some comparison on the Cone nebula last night between my setup and a friend s
    Message 1 of 13 , Feb 18, 2007
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      Hi,
      I am using an Astrodon Ha 6nm filter with my ST10XME. However, after
      running some comparison on the Cone nebula last night between my setup
      and a friend's same filter and ST2000XM, I find my image has a VERY
      low signal (I did use an ST2k in the past with a Schuler filter with
      very good result). Imaging thru the LRGB Astrodon filters doesn't show
      the same problem.
      What do you think is happening? Could it be the camera? I have no
      clue; your help would be much appreciated.
      Thanks!
      I would like to share an image of the cone nebula: 10 minute exposure,
      ST10XME, Astrodon 6nm filter, refractor William Optics 80ED; however I
      don't know how to attach a file... I can send via email to anyone who
      believes he/she can help!
    • Mark de Regt
      In addition to what I said on the other group, a ten minute exposure isn t very long for Ha. My standard Ha exposure is 30 minutes (again, with an Astrodon Ha
      Message 2 of 13 , Feb 18, 2007
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        In addition to what I said on the other group, a ten minute exposure isn't
        very long for Ha. My standard Ha exposure is 30 minutes (again, with an
        Astrodon Ha filter and an ST-10XME).

        Mark de Regt
        Redmond, Washington, USA
        http://www.de-regt.com/Astronomy


        > -----Original Message-----
        > From: ccd-newastro@yahoogroups.com
        > [mailto:ccd-newastro@yahoogroups.com]On Behalf Of vfregembal
        > Sent: Sunday, February 18, 2007 8:53 PM
        > To: ccd-newastro@yahoogroups.com
        > Subject: [ccd-newastro] Astrodon 6nm Ha filter + ST10XME = low signal!?!
        >
        >
        > Hi,
        > I am using an Astrodon Ha 6nm filter with my ST10XME. However, after
        > running some comparison on the Cone nebula last night between my setup
        > and a friend's same filter and ST2000XM, I find my image has a VERY
        > low signal (I did use an ST2k in the past with a Schuler filter with
        > very good result). Imaging thru the LRGB Astrodon filters doesn't show
        > the same problem.
        > What do you think is happening? Could it be the camera? I have no
        > clue; your help would be much appreciated.
        > Thanks!
        > I would like to share an image of the cone nebula: 10 minute exposure,
        > ST10XME, Astrodon 6nm filter, refractor William Optics 80ED; however I
        > don't know how to attach a file... I can send via email to anyone who
        > believes he/she can help!
        >
        >
      • val�rie regembal
        Thanks for your input (and your incredible images!). 10 minute was a test exposure to compare to the St2k image of my friend. The difference was incredible
        Message 3 of 13 , Feb 19, 2007
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          Thanks for your input (and your incredible images!).
          10 minute was a "test" exposure to compare to the St2k image of my friend. The difference was incredible in that my image was very poor. It's hard to comprehend. I also took a 20 minute exposure on the same night which was not much better...
          I don't get it!!!
          Francois


          ---------------------------------
          We won't tell. Get more on shows you hate to love
          (and love to hate): Yahoo! TV's Guilty Pleasures list.

          [Non-text portions of this message have been removed]
        • Yahoo - Wodaski
          If you are imaging with an Ha filter, unless your exposures are at least 10 to 30 minutes each, they are going to be as you describe. And even if you do take
          Message 4 of 13 , Feb 19, 2007
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            If you are imaging with an Ha filter, unless your exposures are at least
            10 to 30 minutes each, they are going to be as you describe. And even
            if you do take exposures that long, you may need several hours total
            exposure time to get a result that looks good.

            Why? A 6nm filter blocks a HUGE percentage of the incoming light is
            blocked, so it takes MUCH longer to build up adequate signal. Long
            individual exposures, and lots of them, are required to image an Ha-rich
            subject. If you are imaging something besides a nebula rich in Ha, then
            much longer times than mentioned will be required to get enough signal.

            You can go to the Files section of this group online to upload a JPG image.

            Ron Wodaski

            vfregembal wrote:
            > Hi,
            > I am using an Astrodon Ha 6nm filter with my ST10XME. However, after
            > running some comparison on the Cone nebula last night between my setup
            > and a friend's same filter and ST2000XM, I find my image has a VERY
            > low signal (I did use an ST2k in the past with a Schuler filter with
            > very good result). Imaging thru the LRGB Astrodon filters doesn't show
            > the same problem.
            > What do you think is happening? Could it be the camera? I have no
            > clue; your help would be much appreciated.
            > Thanks!
            > I would like to share an image of the cone nebula: 10 minute exposure,
            > ST10XME, Astrodon 6nm filter, refractor William Optics 80ED; however I
            > don't know how to attach a file... I can send via email to anyone who
            > believes he/she can help!
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
          • Phil Jones
            Were you each shooting through different scopes? If your friend has more aperture in his scope, then he will get more signal. I use a ST-2000 and a ST-10, and
            Message 5 of 13 , Feb 19, 2007
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              Were you each shooting through different scopes? If your friend has
              more aperture in his scope, then he will get more signal.

              I use a ST-2000 and a ST-10, and occasionally trade my Astrodon 6nm Ha
              filter between the two cameras.

              I use a Stellarvue SV80s refractor with both cameras. For me, the
              ST-10 provided more signal than the ST-2K when I used the 6nm Ha
              filter through the same scope, and imaged the same 2 objects
              (California Nebula and Rosette Nebula). I compared my Ha images and
              found the ST-10 produced more signal, so I deleted the ST-2K images.

              Note: this is not a criticism of the ST-2K, which I love and actually
              use more than the ST-10 due to the ST-2K being anti-blooming. I use
              the ST-10 for galaxies and the ST-2K for nebula and star clusters.

              -Phil J.

              --- In ccd-newastro@yahoogroups.com, "valérie" regembal
              <vfregembal@...> wrote:
              >
              > Thanks for your input (and your incredible images!).
              > 10 minute was a "test" exposure to compare to the St2k image of my
              friend. The difference was incredible in that my image was very poor.
              It's hard to comprehend. I also took a 20 minute exposure on the same
              night which was not much better...
              > I don't get it!!!
              > Francois
              >
              >
              > ---------------------------------
              > We won't tell. Get more on shows you hate to love
              > (and love to hate): Yahoo! TV's Guilty Pleasures list.
              >
              > [Non-text portions of this message have been removed]
              >
            • Don Goldman
              Sorry for the cross-post with the SBIG group, but this may help: Francois, Thanks for sending me one of your raw FITs files. I believe it was from an unbinned
              Message 6 of 13 , Feb 19, 2007
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                Sorry for the cross-post with the SBIG group, but this may help:


                Francois,

                Thanks for sending me one of your raw FITs files. I believe it was
                from an unbinned 20 min single exposure. Since I don't have your
                calibration files, I went into Maxim and did a Median Kernal filter
                to get rid of the hot pixels and then did a mild DDP stretch and
                saved it as a JPEG. Here is the link:

                http://www.astrodon.com/oldsite/NGC2264Min35.jpg

                I think many people in this group would like to have this data. Other
                than some strange looking dark artifacts, it looks like you have
                plenty of signal. Programs like Maxim (my data acquisition program)
                scale the image on the high end to the hot pixels. That compresses
                all of the H-a signal so that it is difficult to see. By using the
                median Kernel filter, the hot pixels are averaged out and the H-a
                image pops out. Comments from the group?

                Don Goldman
                www.astrodon.com



                --- In ccd-newastro@yahoogroups.com, Yahoo - Wodaski <yahoo@...>
                wrote:
                >
                > If you are imaging with an Ha filter, unless your exposures are at
                least
                > 10 to 30 minutes each, they are going to be as you describe. And
                even
                > if you do take exposures that long, you may need several hours
                total
                > exposure time to get a result that looks good.
                >
                > Why? A 6nm filter blocks a HUGE percentage of the incoming light is
                > blocked, so it takes MUCH longer to build up adequate signal. Long
                > individual exposures, and lots of them, are required to image an Ha-
                rich
                > subject. If you are imaging something besides a nebula rich in Ha,
                then
                > much longer times than mentioned will be required to get enough
                signal.
                >
                > You can go to the Files section of this group online to upload a
                JPG image.
                >
                > Ron Wodaski
                >
                > vfregembal wrote:
                > > Hi,
                > > I am using an Astrodon Ha 6nm filter with my ST10XME. However,
                after
                > > running some comparison on the Cone nebula last night between my
                setup
                > > and a friend's same filter and ST2000XM, I find my image has a
                VERY
                > > low signal (I did use an ST2k in the past with a Schuler filter
                with
                > > very good result). Imaging thru the LRGB Astrodon filters doesn't
                show
                > > the same problem.
                > > What do you think is happening? Could it be the camera? I have no
                > > clue; your help would be much appreciated.
                > > Thanks!
                > > I would like to share an image of the cone nebula: 10 minute
                exposure,
                > > ST10XME, Astrodon 6nm filter, refractor William Optics 80ED;
                however I
                > > don't know how to attach a file... I can send via email to anyone
                who
                > > believes he/she can help!
                > >
                > >
                > >
                > > Yahoo! Groups Links
                > >
                > >
                > >
                > >
                >
              • val�rie regembal
                Thank you very much Don for the time you have spent on my image. It was indeed from an unbinned 20 min exposure. Does this image then look acceptable to you
                Message 7 of 13 , Feb 20, 2007
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                  Thank you very much Don for the time you have spent on my image.
                  It was indeed from an unbinned 20 min exposure.
                  Does this image then look acceptable to you given the conditions it was taken under? I used a WO Megrez 80ED refractor.
                  Again, what really struck me on that night was the difference between this image and the one that a friend was acquiring with an St2k and the same Astrodon 6nm filter (granted he was imaging thru a TV101 refractor) with a 20 min exposure unbinned.
                  BTW I'm getting these strange black artifacts all the time: any idea what is causing them?

                  Thanks again very much,

                  Francois


                  ---------------------------------
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                  Try the free Yahoo! Mail Beta.

                  [Non-text portions of this message have been removed]
                • Don Goldman
                  Hi, Francois, I think if you stacked 4 of these 20 min images, and if you dithered your frames during data acquisition, that you would be very happy with the
                  Message 8 of 13 , Feb 22, 2007
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                    Hi, Francois,

                    I think if you stacked 4 of these 20 min images, and if you dithered
                    your frames during data acquisition, that you would be very happy with
                    the results.

                    Several things can cause those dark areas:

                    Do you see them in your raw FITs files with all filters and are they
                    exactly the same in the same place? If so, you may have a dirty optic
                    somewhere. Since they are not diffuse, they would have to be in the
                    camera or on the window going into the camera.

                    If you only see them onefilter, then check the filter and clean if
                    necessary.

                    I don't think this is a problem with darks or flats.

                    ????

                    Regards,

                    Don Goldman
                    www.astrodon.com


                    --- In ccd-newastro@yahoogroups.com, "valérie" regembal
                    <vfregembal@...> wrote:
                    >
                    > Thank you very much Don for the time you have spent on my image.
                    > It was indeed from an unbinned 20 min exposure.
                    > Does this image then look acceptable to you given the conditions
                    it was taken under? I used a WO Megrez 80ED refractor.
                    > Again, what really struck me on that night was the difference
                    between this image and the one that a friend was acquiring with an
                    St2k and the same Astrodon 6nm filter (granted he was imaging thru a
                    TV101 refractor) with a 20 min exposure unbinned.
                    > BTW I'm getting these strange black artifacts all the time: any
                    idea what is causing them?
                    >
                    > Thanks again very much,
                    >
                    > Francois
                    >
                    >
                    > ---------------------------------
                    > Sucker-punch spam with award-winning protection.
                    > Try the free Yahoo! Mail Beta.
                    >
                    > [Non-text portions of this message have been removed]
                    >
                  • Mark de Regt
                    I agree with Don regarding the quality of the subject single image. I think it s fine. I would, however, point out that combining four 20-minute subs taken
                    Message 9 of 13 , Feb 22, 2007
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                      I agree with Don regarding the quality of the subject single image. I think
                      it's fine.

                      I would, however, point out that combining four 20-minute subs taken through
                      a 6nm filter will still likely be noisy. Imaging from the pristine skies of
                      the New Mexico mountains, I did an experiment with my NGC2264 image,
                      processing the pure Ha data in three steps. This was a mosaic. I first
                      took 14 30-minute subs of one pane of the mosaic. Then I took seven of the
                      other. I processed all, and stitched the one with 7 to the one with 14. I
                      could easily tell that the one with "only" 210 minutes of data was noisier
                      than the one with 420. I did it again with ten subs, and still could tell a
                      significant difference. With 14 subs on both sides, the whole thing was
                      very smooth and uniform; seamless.

                      I do understand that I'm a bit of a nut on total exposure time, but I did
                      want to point out that it does help. Especially with Ha data.<g>

                      Mark de Regt
                      Redmond, Washington, USA
                      http://www.de-regt.com/Astronomy


                      > -----Original Message-----
                      > From: ccd-newastro@yahoogroups.com
                      > [mailto:ccd-newastro@yahoogroups.com]On Behalf Of Don Goldman
                      > Sent: Thursday, February 22, 2007 11:49 AM
                      > To: ccd-newastro@yahoogroups.com
                      > Subject: [ccd-newastro] Re: Astrodon 6nm Ha filter + ST10XME = low
                      > signal!?!
                      >
                      >
                      > Hi, Francois,
                      >
                      > I think if you stacked 4 of these 20 min images, and if you dithered
                      > your frames during data acquisition, that you would be very happy with
                      > the results.
                      >
                      > Several things can cause those dark areas:
                      >
                      > Do you see them in your raw FITs files with all filters and are they
                      > exactly the same in the same place? If so, you may have a dirty optic
                      > somewhere. Since they are not diffuse, they would have to be in the
                      > camera or on the window going into the camera.
                      >
                      > If you only see them onefilter, then check the filter and clean if
                      > necessary.
                      >
                      > I don't think this is a problem with darks or flats.
                      >
                      > ????
                      >
                      > Regards,
                      >
                      > Don Goldman
                      > www.astrodon.com
                      >
                      >
                      > --- In ccd-newastro@yahoogroups.com, "valérie" regembal
                      > <vfregembal@...> wrote:
                      > >
                      > > Thank you very much Don for the time you have spent on my image.
                      > > It was indeed from an unbinned 20 min exposure.
                      > > Does this image then look acceptable to you given the conditions
                      > it was taken under? I used a WO Megrez 80ED refractor.
                      > > Again, what really struck me on that night was the difference
                      > between this image and the one that a friend was acquiring with an
                      > St2k and the same Astrodon 6nm filter (granted he was imaging thru a
                      > TV101 refractor) with a 20 min exposure unbinned.
                      > > BTW I'm getting these strange black artifacts all the time: any
                      > idea what is causing them?
                      > >
                      > > Thanks again very much,
                      > >
                      > > Francois
                      > >
                      > >
                      > > ---------------------------------
                      > > Sucker-punch spam with award-winning protection.
                      > > Try the free Yahoo! Mail Beta.
                      > >
                      > > [Non-text portions of this message have been removed]
                      > >
                      >
                      >
                      >
                      >
                      >
                      > Yahoo! Groups - Join or create groups, clubs, forums &
                      > communities. Links
                      >
                      >
                      >
                      >
                    • Yahoo - Wodaski
                      Those dark spots look an awful lot like frost. It s also possible there may have been condensation elsewhere depending on conditions - which could have cut
                      Message 10 of 13 , Feb 22, 2007
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                        Those dark spots look an awful lot like frost. It's also possible there
                        may have been condensation elsewhere depending on conditions - which
                        could have cut signal dramatically.

                        Ron Wodaski

                        Don Goldman wrote:
                        > Hi, Francois,
                        >
                        > I think if you stacked 4 of these 20 min images, and if you dithered
                        > your frames during data acquisition, that you would be very happy with
                        > the results.
                        >
                        > Several things can cause those dark areas:
                        >
                        > Do you see them in your raw FITs files with all filters and are they
                        > exactly the same in the same place? If so, you may have a dirty optic
                        > somewhere. Since they are not diffuse, they would have to be in the
                        > camera or on the window going into the camera.
                        >
                        > If you only see them onefilter, then check the filter and clean if
                        > necessary.
                        >
                        > I don't think this is a problem with darks or flats.
                        >
                        > ????
                        >
                        > Regards,
                        >
                        > Don Goldman
                        > www.astrodon.com
                        >
                        >
                        > --- In ccd-newastro@yahoogroups.com, "valérie" regembal
                        > <vfregembal@...> wrote:
                        >
                        >> Thank you very much Don for the time you have spent on my image.
                        >> It was indeed from an unbinned 20 min exposure.
                        >> Does this image then look acceptable to you given the conditions
                        >>
                        > it was taken under? I used a WO Megrez 80ED refractor.
                        >
                        >> Again, what really struck me on that night was the difference
                        >>
                        > between this image and the one that a friend was acquiring with an
                        > St2k and the same Astrodon 6nm filter (granted he was imaging thru a
                        > TV101 refractor) with a 20 min exposure unbinned.
                        >
                        >> BTW I'm getting these strange black artifacts all the time: any
                        >>
                        > idea what is causing them?
                        >
                        >>
                        >> Thanks again very much,
                        >>
                        >> Francois
                        >>
                        >>
                        >> ---------------------------------
                        >> Sucker-punch spam with award-winning protection.
                        >> Try the free Yahoo! Mail Beta.
                        >>
                        >> [Non-text portions of this message have been removed]
                        >>
                        >>
                        >
                        >
                        >
                        >
                        >
                        > Yahoo! Groups - Join or create groups, clubs, forums & communities. Links
                        >
                        >
                        >
                        >
                      • Rick Wiggins
                        Hi Francois and Ron, Francois, I suggest you bake out the dessicant per my tutorial on my web site. http://home.earthlink.net/~rickwiggins/id23.html I agree
                        Message 11 of 13 , Feb 23, 2007
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                          Hi Francois and Ron,
                          Francois, I suggest you bake out the dessicant per my tutorial on my
                          web site.
                          http://home.earthlink.net/~rickwiggins/id23.html
                          I agree with Ron, and I have seen nearly this exact pattern on my
                          ST10 when it had some moisture.
                          Thanks, Rick

                          --- In ccd-newastro@yahoogroups.com, Yahoo - Wodaski <yahoo@...>
                          wrote:
                          >
                          > Those dark spots look an awful lot like frost. It's also possible
                          there
                          > may have been condensation elsewhere depending on conditions -
                          which
                          > could have cut signal dramatically.
                          >
                          > Ron Wodaski
                          >
                          > Don Goldman wrote:
                          > > Hi, Francois,
                          > >
                          > > I think if you stacked 4 of these 20 min images, and if you
                          dithered
                          > > your frames during data acquisition, that you would be very
                          happy with
                          > > the results.
                          > >
                          > > Several things can cause those dark areas:
                          > >
                          > > Do you see them in your raw FITs files with all filters and are
                          they
                          > > exactly the same in the same place? If so, you may have a dirty
                          optic
                          > > somewhere. Since they are not diffuse, they would have to be in
                          the
                          > > camera or on the window going into the camera.
                          > >
                          > > If you only see them onefilter, then check the filter and clean
                          if
                          > > necessary.
                          > >
                          > > I don't think this is a problem with darks or flats.
                          > >
                          > > ????
                          > >
                          > > Regards,
                          > >
                          > > Don Goldman
                          > > www.astrodon.com
                          > >
                          > >
                          > > --- In ccd-newastro@yahoogroups.com, "valérie" regembal
                          > > <vfregembal@> wrote:
                          > >
                          > >> Thank you very much Don for the time you have spent on my image.
                          > >> It was indeed from an unbinned 20 min exposure.
                          > >> Does this image then look acceptable to you given the
                          conditions
                          > >>
                          > > it was taken under? I used a WO Megrez 80ED refractor.
                          > >
                          > >> Again, what really struck me on that night was the difference
                          > >>
                          > > between this image and the one that a friend was acquiring with
                          an
                          > > St2k and the same Astrodon 6nm filter (granted he was imaging
                          thru a
                          > > TV101 refractor) with a 20 min exposure unbinned.
                          > >
                          > >> BTW I'm getting these strange black artifacts all the time:
                          any
                          > >>
                          > > idea what is causing them?
                          > >
                          > >>
                          > >> Thanks again very much,
                          > >>
                          > >> Francois
                          > >>
                          > >>
                          > >> ---------------------------------
                          > >> Sucker-punch spam with award-winning protection.
                          > >> Try the free Yahoo! Mail Beta.
                          > >>
                          > >> [Non-text portions of this message have been removed]
                          > >>
                          > >>
                          > >
                          > >
                          > >
                          > >
                          > >
                          > > Yahoo! Groups - Join or create groups, clubs, forums &
                          communities. Links
                          > >
                          > >
                          > >
                          > >
                          >
                        • val�rie regembal
                          Thanks Rick and Don, I will bake the dessicant: I just thought I would not need to do that before at least a few months of usage though... This was the second
                          Message 12 of 13 , Feb 28, 2007
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                            Thanks Rick and Don,

                            I will bake the dessicant: I just thought I would not need to do that before at least a few months of usage though... This was the second time the new camera went out!

                            Also, I don't really understand the term "dithered your frames during data acquisition"... Can you elaborate a little bit on that? Forgive my candid question!

                            Francois


                            ---------------------------------
                            The fish are biting.
                            Get more visitors on your site using Yahoo! Search Marketing.

                            [Non-text portions of this message have been removed]
                          • Don Goldman
                            Francois, Dithering is a method to offset each frame a few pixels so that hot pixels don t overlap when combining, for example. This helps to ensure that these
                            Message 13 of 13 , Feb 28, 2007
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                              Francois,

                              Dithering is a method to offset each frame a few pixels so that hot
                              pixels don't overlap when combining, for example. This helps to
                              ensure that these artifacts get "averaged out". Several data
                              acquisition programs, like Maxim, CCDAutoPilot, CCDCommander, do
                              this automatically for you.

                              Don Goldman
                              www.astrodon.com


                              --- In ccd-newastro@yahoogroups.com, "valérie" regembal
                              <vfregembal@...> wrote:
                              >
                              > Thanks Rick and Don,
                              >
                              > I will bake the dessicant: I just thought I would not need to do
                              that before at least a few months of usage though... This was the
                              second time the new camera went out!
                              >
                              > Also, I don't really understand the term "dithered your frames
                              during data acquisition"... Can you elaborate a little bit on that?
                              Forgive my candid question!
                              >
                              > Francois
                              >
                              >
                              > ---------------------------------
                              > The fish are biting.
                              > Get more visitors on your site using Yahoo! Search Marketing.
                              >
                              > [Non-text portions of this message have been removed]
                              >
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