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Re: [ccd-newastro] Re: Help: Electroluminescent panel. Black frames through Green, Blue and SII

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  • Marco Lorenzi
    It is not possible that you get a fine flat on OIII and nothing in the Blue channel since the latter contain (partially) OIII. Same for RED and SII. As
    Message 1 of 15 , Mar 1, 2011
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      It is not possible that you get a fine flat on OIII and nothing in the Blue
      channel since the latter contain (partially) OIII. Same for RED and SII. As
      somebody else suggested you are not getting an absolutely *black* frames, you
      are (quite the opposite) very probably over-exposing. I used and am using both
      commercial (FlipFlat) and home made EL panels and all works great.

      Clear Skies
      Marco




      ________________________________


      --- In ccd-newastro@yahoogroups.com, "freeecopower" <freeecopower@...> wrote:
      >
      > Hi there,
      >
      > after reading some posts on DIY electroluminescent panels for flat fields I
      >went ahead and build one myself:
      >
      > http://www.directlinking.net/astro/el.JPG
      >
      > To my surprise (found out last night) I get absolutely black frames through
      >Green, Blue and SII filters while Red, Ha, and OIII are totally fine.
      >
      > No matter how long I would expose (didn't try longer than 60 sec exposures on
      >those) the frames would remain black.
      >
      > Frames trough Luminance filter were strange too, had bright streaks running
      >from top to bottom and concentrating mostly on top right side of the frame. Too
      >bad I didn't save an example. I could produce that tomorrow though.
      >
      > Anyways the camera used is SXVR-H18, LRGB filters from Orion and Ha SII and
      >OIII are Astrodon 5nm.
      >
      > If anyone is using EL panels for flat fields please advise what is going on.
      >Initially I thought perhaps the panels don't emit the light in those
      >wavelengths, but since I couldn't find anyone using them reporting those kind of
      >issues I figured it's not the case.
      >
      > If anyone knows of the possible issue please take a few minutes and send a
      >message.
      >
      > I appreciate your time.
      >
      > Thank you!
      >
      > Darius
      >







      [Non-text portions of this message have been removed]
    • freeecopower
      So it sounds like I m overexposing. I started at 3 sec (dimmed to lowest setting) for Red filter and it worked well. 3 sec for Green and Blue produced black
      Message 2 of 15 , Mar 1, 2011
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        So it sounds like I'm overexposing. I started at 3 sec (dimmed to lowest setting) for Red filter and it worked well. 3 sec for Green and Blue produced black frames so it didn't even occurred to me to go lower so I went higher.

        I tried 1 sec on Luminance filter and it wasn't good, if this was due to overexposure then I need to dim it considerably. I'll try it again tonight. Will take better notes and save some frames.

        Thanks for the advice.

        Darius
      • JoeMize
        Darius, if you don t have a Dimmer for your ELP you could try the Sky Flats Assistant Plug-In for MaximDL. It works just as well on ELP s as it does for
        Message 3 of 15 , Mar 1, 2011
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          Darius, if you don't have a Dimmer for your ELP you could try the 'Sky Flats Assistant' Plug-In for MaximDL. It works just as well on ELP's as it does for real Sky Flats. But for best results with or without Sky Flats Assistant you should have a Dimmer on your ELP.

          Sky Flats Assistant will automatically adjust exposure times to match your Flat ADU Target Value. But remember your exposure times should be long enough to fully illuminate your Flat without being too short. For my LRGB Flats I go for ~5sec. NB filters require longer exposures because they're so dense.

          I've used Sky Flats Assistant for my AP155, my RCOS 12.5", and another 12.5" astrograph with great success. HTH...joe :) http://winfij.homeip.net/maximdl/skyflats.html

          PS: The formula I use for determining my Flat Target Value:
          Full Well / Gain x Bin x 42.74% (0.4274) = Flat ADU Target
          ...Full Well = SBIG's stated value.
          ...Gain = from camera's FITS Header, 'not' SBIG's value.


          "May You Go Among The Imperishable Stars"
          Joe Mize www.cav-sfo.com
          Chiefland Astronomy Village, Fla
          StarFields Observatory, (SFO).

          ----- Original Message -----
          From: "mmanner" <mark.manner@...>
          To: <ccd-newastro@yahoogroups.com>
          Sent: Monday, February 28, 2011 8:09 PM
          Subject: [ccd-newastro] Re: Help: Electroluminescent panel. Black frames through Green, Blue and SII


          >I don't have DIY EL panel experience, but I am using a couple of Flip-Flats that use EL panels, and they are working fine on LRGBHaSIIOIII and IR filters. I have to adjust the light output for the different filters, but after figuring out the right levels, the flats are coming out just as expected (like a good sky flat). I would try reducing the EL panel output or reducing the exposure for each filter until you get an average adu count of 10,000 or so(or whatever is appropriate for your chip). What camera control software are you using? 60 seconds is a long time for a flat, so probably you are overexposed.
          >
          > --- In ccd-newastro@yahoogroups.com, "freeecopower" <freeecopower@...> wrote:
          >>
          >> Hi there,
          >>
          >> after reading some posts on DIY electroluminescent panels for flat fields I went ahead and build one myself:
          >>
          >> http://www.directlinking.net/astro/el.JPG
          >>
          >> To my surprise (found out last night) I get absolutely black frames through Green, Blue and SII filters while Red, Ha, and OIII are totally fine.
          >>
          >> No matter how long I would expose (didn't try longer than 60 sec exposures on those) the frames would remain black.
          >>
          >> Frames trough Luminance filter were strange too, had bright streaks running from top to bottom and concentrating mostly on top right side of the frame. Too bad I didn't save an example. I could produce that tomorrow though.
          >>
          >> Anyways the camera used is SXVR-H18, LRGB filters from Orion and Ha SII and OIII are Astrodon 5nm.
          >>
          >> If anyone is using EL panels for flat fields please advise what is going on. Initially I thought perhaps the panels don't emit the light in those wavelengths, but since I couldn't find anyone using them reporting those kind of issues I figured it's not the case.
          >>
          >> If anyone knows of the possible issue please take a few minutes and send a message.
          >>
          >> I appreciate your time.
          >>
          >> Thank you!
          >>
          >> Darius
          >>
          >
          >
          >
          >
          > ------------------------------------
          >
          >
          >
          >
          >

          [Non-text portions of this message have been removed]
        • freeecopower
          Thanks Joe for pointing to Sky Flats Assistant plugin, I am using MaximDL but didn t know about the plugin. So it sounds like I m overexposing. I started at
          Message 4 of 15 , Mar 1, 2011
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            Thanks Joe for pointing to 'Sky Flats Assistant' plugin, I am using MaximDL but didn't know about the plugin.

            So it sounds like I'm overexposing. I started at 3 sec (dimmed to lowest setting) for Red filter and it worked well. 3 sec for Green and Blue produced black frames so it didn't even occurred to me to go lower so I went higher.

            I tried 1 sec on Luminance filter and it wasn't good, if this was due to overexposure then I need to dim it considerably.

            I've just glued two sheets of thick stencil paper in front of the panel. This should further dim the light.

            I'll try it again tonight. Will take better notes and save some frames.

            Thanks for the advice.

            Darius

            --- In ccd-newastro@yahoogroups.com, "JoeMize" <jmize@...> wrote:
            >
            > Darius, if you don't have a Dimmer for your ELP you could try the 'Sky Flats Assistant' Plug-In for MaximDL. It works just as well on ELP's as it does for real Sky Flats. But for best results with or without Sky Flats Assistant you should have a Dimmer on your ELP.
            >
            > Sky Flats Assistant will automatically adjust exposure times to match your Flat ADU Target Value. But remember your exposure times should be long enough to fully illuminate your Flat without being too short. For my LRGB Flats I go for ~5sec. NB filters require longer exposures because they're so dense.
            >
            > I've used Sky Flats Assistant for my AP155, my RCOS 12.5", and another 12.5" astrograph with great success. HTH...joe :) http://winfij.homeip.net/maximdl/skyflats.html
            >
            > PS: The formula I use for determining my Flat Target Value:
            > Full Well / Gain x Bin x 42.74% (0.4274) = Flat ADU Target
            > ...Full Well = SBIG's stated value.
            > ...Gain = from camera's FITS Header, 'not' SBIG's value.
            >
            >
            > "May You Go Among The Imperishable Stars"
            > Joe Mize www.cav-sfo.com
            > Chiefland Astronomy Village, Fla
            > StarFields Observatory, (SFO).
            >
            > ----- Original Message -----
            > From: "mmanner" <mark.manner@...>
            > To: <ccd-newastro@yahoogroups.com>
            > Sent: Monday, February 28, 2011 8:09 PM
            > Subject: [ccd-newastro] Re: Help: Electroluminescent panel. Black frames through Green, Blue and SII
            >
            >
            > >I don't have DIY EL panel experience, but I am using a couple of Flip-Flats that use EL panels, and they are working fine on LRGBHaSIIOIII and IR filters. I have to adjust the light output for the different filters, but after figuring out the right levels, the flats are coming out just as expected (like a good sky flat). I would try reducing the EL panel output or reducing the exposure for each filter until you get an average adu count of 10,000 or so(or whatever is appropriate for your chip). What camera control software are you using? 60 seconds is a long time for a flat, so probably you are overexposed.
            > >
            > > --- In ccd-newastro@yahoogroups.com, "freeecopower" <freeecopower@> wrote:
            > >>
            > >> Hi there,
            > >>
            > >> after reading some posts on DIY electroluminescent panels for flat fields I went ahead and build one myself:
            > >>
            > >> http://www.directlinking.net/astro/el.JPG
            > >>
            > >> To my surprise (found out last night) I get absolutely black frames through Green, Blue and SII filters while Red, Ha, and OIII are totally fine.
            > >>
            > >> No matter how long I would expose (didn't try longer than 60 sec exposures on those) the frames would remain black.
            > >>
            > >> Frames trough Luminance filter were strange too, had bright streaks running from top to bottom and concentrating mostly on top right side of the frame. Too bad I didn't save an example. I could produce that tomorrow though.
            > >>
            > >> Anyways the camera used is SXVR-H18, LRGB filters from Orion and Ha SII and OIII are Astrodon 5nm.
            > >>
            > >> If anyone is using EL panels for flat fields please advise what is going on. Initially I thought perhaps the panels don't emit the light in those wavelengths, but since I couldn't find anyone using them reporting those kind of issues I figured it's not the case.
            > >>
            > >> If anyone knows of the possible issue please take a few minutes and send a message.
            > >>
            > >> I appreciate your time.
            > >>
            > >> Thank you!
            > >>
            > >> Darius
            > >>
            > >
            > >
            > >
            > >
            > > ------------------------------------
            > >
            > >
            > >
            > >
            > >
            >
            > [Non-text portions of this message have been removed]
            >
          • Stan
            ... Depending on the camera, it may be ill-advised to use Flat exps shorter than 1 sec (approx) due to shutter issues. e.g. SBIG ST cameras use a rotating
            Message 5 of 15 , Mar 1, 2011
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              --- "freeecopower" <dariuskersulis@...> wrote:
              > 0.3 sec for Green and Blue...

              Depending on the camera, it may be ill-advised to use Flat exps shorter than 1 sec (approx) due to shutter issues. e.g. SBIG ST cameras use a rotating blade that for very short exps can produce a slightly uneven exp across the frame. Also, frame transfer CCD and CMOS with no mechanical shutter may produce atypical flats at very short exps times (e.g. 1/1000 sec).

              It looks like you may need to install a dimmer.

              Stan
            • Don
              Darius, If you have trouble dimming your EL panel enough, you can cover it with a couple layers of white T-shirt cloth. Just my thoughts, Don Waid ... From:
              Message 6 of 15 , Mar 1, 2011
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                Darius,

                If you have trouble dimming your EL panel enough, you can cover it with a
                couple layers of white "T-shirt" cloth.

                Just my thoughts,

                Don Waid

                ----- Original Message -----
                From: "freeecopower" <dariuskersulis@...>
                To: <ccd-newastro@yahoogroups.com>
                Sent: Tuesday, March 01, 2011 8:05 AM
                Subject: [ccd-newastro] Re: Help: Electroluminescent panel. Black frames
                through Green, Blue and SII


                > So it sounds like I'm overexposing. I started at 3 sec (dimmed to lowest
                > setting) for Red filter and it worked well. 3 sec for Green and Blue
                > produced black frames so it didn't even occurred to me to go lower so I
                > went higher.
                >
                > I tried 1 sec on Luminance filter and it wasn't good, if this was due to
                > overexposure then I need to dim it considerably. I'll try it again
                > tonight. Will take better notes and save some frames.
                >
                > Thanks for the advice.
                >
                > Darius
                >
                >
                >
                > ------------------------------------
                >
                >
                >
                >
              • Mike Dodd
                ... Has this been verified and proven? The only way an uneven exposure could occur is if the motor did not accelerate the shutter to full speed before the
                Message 7 of 15 , Mar 1, 2011
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                  Stan wrote:
                  > SBIG ST cameras use a rotating blade that for very short exps can produce a
                  > slightly uneven exp across the frame.

                  Has this been verified and proven? The only way an uneven exposure could
                  occur is if the motor did not accelerate the shutter to full speed
                  before the opening reached the edge of the chip.

                  Rotary shutters have been used with still and movie film cameras (and
                  movie projectors) for decades. I once owned a Mercury II half-frame 35mm
                  camera with a rotary shutter
                  <http://rick_oleson.tripod.com/index-25.html>. Exposures were uniform at
                  shutter speeds from 1/20s to 1/1000s.

                  So I'm curious if the claims of uneven ST short exposures have been
                  confirmed. If so, I'm also curious about why/how it occurs.
                  --
                  Mike

                  Mike Dodd
                  Louisa, VA USA
                  http://astronomy.mdodd.com

                  Building a new observatory in 2011
                  http://house.mdodd.com/observatory.html
                • Ron Wodaski
                  The shutters are pretty slow. You do need 1 second exposures. Otherwise, some parts of the chip get significantly more exposure time than others. Ron Wodaski
                  Message 8 of 15 , Mar 1, 2011
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                    The shutters are pretty slow. You do need > 1 second exposures. Otherwise, some parts of the chip get significantly more exposure time than others.

                    Ron Wodaski



                    On Mar 1, 2011, at 7:15 AM, Mike Dodd wrote:

                    > Stan wrote:
                    >> SBIG ST cameras use a rotating blade that for very short exps can produce a
                    >> slightly uneven exp across the frame.
                    >
                    > Has this been verified and proven? The only way an uneven exposure could
                    > occur is if the motor did not accelerate the shutter to full speed
                    > before the opening reached the edge of the chip.
                    >
                    > Rotary shutters have been used with still and movie film cameras (and
                    > movie projectors) for decades. I once owned a Mercury II half-frame 35mm
                    > camera with a rotary shutter
                    > <http://rick_oleson.tripod.com/index-25.html>. Exposures were uniform at
                    > shutter speeds from 1/20s to 1/1000s.
                    >
                    > So I'm curious if the claims of uneven ST short exposures have been
                    > confirmed. If so, I'm also curious about why/how it occurs.
                    > --
                    > Mike
                    >
                    > Mike Dodd
                    > Louisa, VA USA
                    > http://astronomy.mdodd.com
                    >
                    > Building a new observatory in 2011
                    > http://house.mdodd.com/observatory.html
                    >
                    >
                    > ------------------------------------
                    >
                    >
                    >
                    >
                  • freeecopower
                    Problem solved! Couple of layers of stencil paper reduced the exposure times enough to make good flats. Now I have 2 sec on Luminance 1x1, 2 sec for Blue and
                    Message 9 of 15 , Mar 2, 2011
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                      Problem solved! Couple of layers of stencil paper reduced the exposure times enough to make good flats. Now I have 2 sec on Luminance 1x1, 2 sec for Blue and Green 2x2 and 5 sec for Red 2x2. Didn't bother doing the NB simply because I was too excited, figured it will be just fine, and rushed to get some subs for Horsehead nebula before it goes beyond the trees.

                      Thank you all for the feedback!

                      Darius



                      --- In ccd-newastro@yahoogroups.com, "freeecopower" <freeecopower@...> wrote:
                      >
                      > Hi there,
                      >
                      > after reading some posts on DIY electroluminescent panels for flat fields I went ahead and build one myself:
                      >
                      > http://www.directlinking.net/astro/el.JPG
                      >
                      > To my surprise (found out last night) I get absolutely black frames through Green, Blue and SII filters while Red, Ha, and OIII are totally fine.
                      >
                      > No matter how long I would expose (didn't try longer than 60 sec exposures on those) the frames would remain black.
                      >
                      > Frames trough Luminance filter were strange too, had bright streaks running from top to bottom and concentrating mostly on top right side of the frame. Too bad I didn't save an example. I could produce that tomorrow though.
                      >
                      > Anyways the camera used is SXVR-H18, LRGB filters from Orion and Ha SII and OIII are Astrodon 5nm.
                      >
                      > If anyone is using EL panels for flat fields please advise what is going on. Initially I thought perhaps the panels don't emit the light in those wavelengths, but since I couldn't find anyone using them reporting those kind of issues I figured it's not the case.
                      >
                      > If anyone knows of the possible issue please take a few minutes and send a message.
                      >
                      > I appreciate your time.
                      >
                      > Thank you!
                      >
                      > Darius
                      >
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