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RE: [ccd-newastro] Laptop screen light box

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  • ChrisEGroup
    Hi, I have been trying this with my 8 SCT with mixed results. As Ron points out, the intensity of any area of the screen varies with the viewing angle. I have
    Message 1 of 8 , Oct 4, 2001
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      Hi,

      I have been trying this with my 8" SCT with mixed results. As Ron points
      out, the intensity of any area of the screen varies with the viewing
      angle. I have not found a convenient way to get the scope and the screen
      parallel. With that said, I have gotten some good flats. In this case
      good means: no obvious gradients, low noise and in this case, screen
      flats that are similar to "standard" flats. I check them by subtracting
      one from the other and also flatting one with the other. The result is
      always a slightly noisy but otherwise uniform image if the screen flat
      is made well.

      I am hoping that my new 4" refractor might have a better time of it
      since it should be easier align well and is much smaller in aperture
      than any screen dimensions.

      On a side note, my new 4" is the William Optics 80-mm refractor
      (reviewed in October Sky&Telescope). While I have not taken any CCD
      images with it yet (waiting for mounting hardware and my new mount)
      Causal viewing has been really enjoyable. Nice pointy stars with very
      little color aberrations (mostly a VERY slight smearing on bright
      stars).

      The moon, M42 and the Pleades as well as another cluster I have yet to
      identify all looked fabulous. Mars was a nice sharp round disk with a
      really nice "mars" red color. I have been using a 9mm, 26mm and 34mm
      Plossel EP's from my LX90 kit. I've had to use them with my 2x balow
      because of the one and only problem I've had: I can't get any of my eye
      pieces to focus on their own. In the supplied diagonal, I can't focus in
      far enough and without it, I can't focus out far enough. Very annoying!
      I assume this is an issue with most refractors? The review in S&T did
      not mention this.

      The refractor came with a nice set of mounting rings, a 2" mirror
      diagonal and a nice carrying case. The quality looks really good. I'm
      exited to have this as a complement to my 8" SCT. I would recommend this
      to anyone looking for a nice but reasonably inexpensive second scope,
      especially if your primary experience is with the SCT's. I am really
      enjoying the differences and the pros and cons of each.


      Chris

      PS - I have new pictures taken on the 25th posted at my site. Please
      feel free to drop by and check them out.

      -C



      Chris Levin
      Renton, WA 98058
      N 47d 25m 42.9s W 122d 9m 38.3s <http://www.rocklizard.org/>
      http://www.rocklizard.org
      mailto:chrisweb@...

      -----Original Message-----
      From: Ron Wodaski [mailto:ronw@...]
      Sent: Thursday, October 04, 2001 2:05 PM
      To: ccd-newastro@yahoogroups.com
      Subject: RE: [ccd-newastro] Laptop screen light box


      I would question how even the illumination direct from the screen would
      be.
      You would need additional diffusers, since most screens are going to
      offer
      different levels of illumination with different seeing angles. The
      extreme
      sensitivity of a CCD chip means that it could well give you gradients
      even
      if the screen _looks_ evenly illuminated to your eye.

      And of course this would only work for smaller apertures. <g>

      Feel free to give it a try; it's an intriguing idea. You can pick up
      translucent plastic panels to use the additional diffusing layers at
      many
      hardware stores, or at places that handle sheet plastic. A sandwich of 2
      or
      3 such additional layers, with some air space between them might well
      get
      the job done.

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

      -----Original Message-----
      From: gjensen@... [mailto:gjensen@...]
      Sent: Thursday, October 04, 2001 1:57 PM
      To: ccd-newastro@yahoogroups.com
      Subject: [ccd-newastro] Laptop screen light box


      I've started thinking about building a light box and
      it occurred to me that my laptop screen can possibly
      be a ready made light box.
      Is that possible?
      Can I vary intensity by changing the shade of grey on
      the laptop screen?
      Has anyone tried this?

      Gary



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      [Non-text portions of this message have been removed]
    • Ron Wodaski
      One idea: use the laptop screen for illumination, but put one or two layers of translucent plastic over the front of your scope for a diffuser. Aiming will be
      Message 2 of 8 , Oct 4, 2001
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        One idea: use the laptop screen for illumination, but put one or two layers
        of translucent plastic over the front of your scope for a diffuser. Aiming
        will be less critical, and the increased distance between the source and the
        diffuser could help even out illumination more easily and repeatably.

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

        -----Original Message-----
        From: ChrisEGroup [mailto:ChrisEGroup@...]
        Sent: Thursday, October 04, 2001 6:16 PM
        To: ccd-newastro@yahoogroups.com
        Subject: RE: [ccd-newastro] Laptop screen light box


        Hi,

        I have been trying this with my 8" SCT with mixed results. As Ron points
        out, the intensity of any area of the screen varies with the viewing
        angle. I have not found a convenient way to get the scope and the screen
        parallel. With that said, I have gotten some good flats. In this case
        good means: no obvious gradients, low noise and in this case, screen
        flats that are similar to "standard" flats. I check them by subtracting
        one from the other and also flatting one with the other. The result is
        always a slightly noisy but otherwise uniform image if the screen flat
        is made well.

        I am hoping that my new 4" refractor might have a better time of it
        since it should be easier align well and is much smaller in aperture
        than any screen dimensions.

        On a side note, my new 4" is the William Optics 80-mm refractor
        (reviewed in October Sky&Telescope). While I have not taken any CCD
        images with it yet (waiting for mounting hardware and my new mount)
        Causal viewing has been really enjoyable. Nice pointy stars with very
        little color aberrations (mostly a VERY slight smearing on bright
        stars).

        The moon, M42 and the Pleades as well as another cluster I have yet to
        identify all looked fabulous. Mars was a nice sharp round disk with a
        really nice "mars" red color. I have been using a 9mm, 26mm and 34mm
        Plossel EP's from my LX90 kit. I've had to use them with my 2x balow
        because of the one and only problem I've had: I can't get any of my eye
        pieces to focus on their own. In the supplied diagonal, I can't focus in
        far enough and without it, I can't focus out far enough. Very annoying!
        I assume this is an issue with most refractors? The review in S&T did
        not mention this.

        The refractor came with a nice set of mounting rings, a 2" mirror
        diagonal and a nice carrying case. The quality looks really good. I'm
        exited to have this as a complement to my 8" SCT. I would recommend this
        to anyone looking for a nice but reasonably inexpensive second scope,
        especially if your primary experience is with the SCT's. I am really
        enjoying the differences and the pros and cons of each.


        Chris

        PS - I have new pictures taken on the 25th posted at my site. Please
        feel free to drop by and check them out.

        -C



        Chris Levin
        Renton, WA 98058
        N 47d 25m 42.9s W 122d 9m 38.3s <http://www.rocklizard.org/>
        http://www.rocklizard.org
        mailto:chrisweb@...

        -----Original Message-----
        From: Ron Wodaski [mailto:ronw@...]
        Sent: Thursday, October 04, 2001 2:05 PM
        To: ccd-newastro@yahoogroups.com
        Subject: RE: [ccd-newastro] Laptop screen light box


        I would question how even the illumination direct from the screen would
        be.
        You would need additional diffusers, since most screens are going to
        offer
        different levels of illumination with different seeing angles. The
        extreme
        sensitivity of a CCD chip means that it could well give you gradients
        even
        if the screen _looks_ evenly illuminated to your eye.

        And of course this would only work for smaller apertures. <g>

        Feel free to give it a try; it's an intriguing idea. You can pick up
        translucent plastic panels to use the additional diffusing layers at
        many
        hardware stores, or at places that handle sheet plastic. A sandwich of 2
        or
        3 such additional layers, with some air space between them might well
        get
        the job done.

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

        -----Original Message-----
        From: gjensen@... [mailto:gjensen@...]
        Sent: Thursday, October 04, 2001 1:57 PM
        To: ccd-newastro@yahoogroups.com
        Subject: [ccd-newastro] Laptop screen light box


        I've started thinking about building a light box and
        it occurred to me that my laptop screen can possibly
        be a ready made light box.
        Is that possible?
        Can I vary intensity by changing the shade of grey on
        the laptop screen?
        Has anyone tried this?

        Gary



        To unsubscribe from this group, send an email to:
        ccd-newastro-unsubscribe@egroups.com



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        http://docs.yahoo.com/info/terms/




        Yahoo! Groups Sponsor

        ADVERTISEMENT



        <http://rd.yahoo.com/M=194081.1637497.3177299.1261774/D=egroupweb/S=1705
        082829:HM/A=793313/R=1/*http://www.ediets.com/start.cfm?code=3256>

        <http://us.adserver.yahoo.com/l?M=194081.1637497.3177299.1261774/D=egrou
        pmail/S=1705082829:HM/A=793313/rand=888219354>

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



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      • Eileen Chun
        Okay this is a long shot way over in left field, but you know those green colored panels you find in night lights, will that not work? -Eileen ... [Non-text
        Message 3 of 8 , Oct 5, 2001
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          Okay this is a long shot way over in left field, but you know those green
          colored panels you find in night lights, will that not work?

          -Eileen


          >


          [Non-text portions of this message have been removed]
        • Paul K
          This is actually how I ve been doing flats for the past year. In order to get a more even illumination, I point the laptop screen at a nearby white wall. I
          Message 4 of 8 , Oct 5, 2001
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            This is actually how I've been doing flats for the past year. In
            order to get a more even illumination, I point the laptop screen at a
            nearby white wall. I then point the telescope at the wall. I keep the
            screen not too bright, so as to take a 20-30 second exposure. I leave
            the RA motor tracking while taking the exposure. The RA motion plus
            the fact that the wall is out of focus seems to produce very usable,
            evenly illuminated flats.

            -Paul

            --- In ccd-newastro@y..., "Ron Wodaski" <ronw@n...> wrote:
            > I would question how even the illumination direct from the screen
            would be.
            > You would need additional diffusers, since most screens are going
            to offer
            > different levels of illumination with different seeing angles. The
            extreme
            > sensitivity of a CCD chip means that it could well give you
            gradients even
            > if the screen _looks_ evenly illuminated to your eye.
            >
            > And of course this would only work for smaller apertures. <g>
            >
            > Feel free to give it a try; it's an intriguing idea. You can pick up
            > translucent plastic panels to use the additional diffusing layers
            at many
            > hardware stores, or at places that handle sheet plastic. A sandwich
            of 2 or
            > 3 such additional layers, with some air space between them might
            well get
            > the job done.
            >
            > Ron Wodaski
            > The New CCD Astronomy
            > http://www.newastro.com
            >
            > -----Original Message-----
            > From: gjensen@f... [mailto:gjensen@f...]
            > Sent: Thursday, October 04, 2001 1:57 PM
            > To: ccd-newastro@y...
            > Subject: [ccd-newastro] Laptop screen light box
            >
            >
            > I've started thinking about building a light box and
            > it occurred to me that my laptop screen can possibly
            > be a ready made light box.
            > Is that possible?
            > Can I vary intensity by changing the shade of grey on
            > the laptop screen?
            > Has anyone tried this?
            >
            > Gary
            >
            >
            >
            > To unsubscribe from this group, send an email to:
            > ccd-newastro-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to
            http://docs.yahoo.com/info/terms/
          • Peter Moreton
            Tim, I purchased a couple of these illumination panels when I was in Hong Kong last time. I purchased small panels, 3 * 5cm sized, costing about ?3 ea. They
            Message 5 of 8 , Oct 5, 2001
            • 0 Attachment
              Tim,

              I purchased a couple of these illumination panels when I was in Hong Kong
              last time. I purchased small panels, 3 * 5cm sized, costing about ?3 ea.
              They take the form of a piece of thin card, with two metalised terminals. I
              have not had time to use them yet, and in fact have not been able to find
              details of the required drive circuits, (these devices do not appear run
              from low voltage DC). Does anyone know how to get these panels to operate?

              I am sure I could get these shipped over from Hong Kong if a few people on
              the list wanted one...

              Regards,

              ----------------------
              Peter Moreton
              Rockingham Instruments (CCD Imagers)

              Web: www.rockinghaminstruments.com


              -----Original Message-----
              From: Timothy Long [mailto:Tim@...]
              Sent: 05 October 2001 01:27
              To: 'ccd-newastro@yahoogroups.com'
              Subject: [ccd-newastro] Re: Laptop screen light box


              I've been working on a similar idea. My inspiration also came from laptop
              screens, but rather than using the whole screen, I've been looking for a
              source of electroluminescent panels (the part that provides the
              illumination). I really want to make this work because the panels are so
              lightweight and compact. It might be perfectly feasible to build a light box
              right into the dust cap of your telescope. The trouble is, I haven't found a
              supplier of the panels yet. I'm currently following up a lead in Taiwan but
              I think the chances of getting a 1-off from them are small.

              As Ron mentions, the illumination may not be even enough, but with extra
              diffusion it might just work. The potential benefits make it worth at least
              experimenting with. I'd be interested to hear from anyone who has a source
              of electroluminescent panels or who has already tried this idea.

              Regards,
              Tim Long


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



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