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Banding- Answered!

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  • kflor@comcast.net
    From Andrew, with his permission. Hi Ken, First I will address the banding issue that you mention in your e-mails. Internal etalon systems have a few
    Message 1 of 15 , Mar 26, 2009
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      From Andrew, with his permission.


      Hi Ken,

      First I will address the "banding" issue that you mention in your e-mails.

      Internal etalon systems have a few compromises when compared to external front mounted etalons.
      The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
      As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.

      The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
      However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
      The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
      This has the effect of a slight bird shape (with regard to contrast) across the field.
      As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
      We have optimized for as flat a field as physics will allow.

      The other issue is due to the fact that our internal etalons are tiltable.

      Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
      Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.

      I have replied to many e-mails from customers who state that the tuner does very little.
      They are absolutely correct.
      The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
      The tilt mechanism does not work like the tilt mechanism on the front of a system.

      The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.

      When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
      As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
      The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
      At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.

      When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.

      Double Stacking.

      If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
      When doublestacked, the proms generally fade and the surface has more contrast and has better detail.

      If the field was flattened well in single mode, the field should be fairly flat in DS mode.

      There are a few subtle things that can be done to improve the system's performance.

      Make sure the area you wish to observe is in the center of the eyepiece.
      Tune the LS60T to the furthest to the right position possible with the tilt knob.
      Place the LS50F on the front and tune for the best surface detail.
      Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
      Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
      An O-ring or some felt may help if it goes more than 1/4 turn.

      You will note the surface contrast will alter. Getting better and then worse as you turn.
      There will be a point where the surface should pop a little better and the "band" almost eliminated.

      Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.

      Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
      This system is currently available on our LS100T and really works well.

      Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
      Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.

      I hope the above explains a little of what is going on.
      We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.

      Andrew Lunt
      Lunt Solar Systems LLC
      2520 N. Coyote Drive. Suite 111
      Tucson, AZ 85745
      USA
      Tel: (520) 344 7348
      Fax: (520) 344 7352
      www.luntsolarsystems.com


      Andrew Lunt
      Lunt Solar Systems LLC
      2520 N. Coyote Drive. Suite 111
      Tucson, AZ 85745
      USA
      Tel: (520) 344 7348
      Fax: (520) 344 7352
      www.luntsolarsystems.com
    • paulk@saber.net
      Thank you Andy! Does the 1/4 turn trick apply to front pairs of etalons? Paulk Sent from my Verizon Wireless BlackBerry ... From: kflor@comcast.net Date: Thu,
      Message 2 of 15 , Mar 26, 2009
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        Thank you Andy!
        Does the 1/4 turn trick apply to front pairs of etalons?
        Paulk
        Sent from my Verizon Wireless BlackBerry

        -----Original Message-----
        From: kflor@...

        Date: Thu, 26 Mar 2009 16:42:31
        To: <luntsolar@yahoogroups.com>
        Subject: [luntsolar] Banding- Answered!


        >From Andrew, with his permission.


        Hi Ken,

        First I will address the "banding" issue that you mention in your e-mails.

        Internal etalon systems have a few compromises when compared to external front mounted etalons.
        The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
        As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.

        The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
        However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
        The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
        This has the effect of a slight bird shape (with regard to contrast) across the field.
        As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
        We have optimized for as flat a field as physics will allow.

        The other issue is due to the fact that our internal etalons are tiltable.

        Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
        Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.

        I have replied to many e-mails from customers who state that the tuner does very little.
        They are absolutely correct.
        The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
        The tilt mechanism does not work like the tilt mechanism on the front of a system.

        The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.

        When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
        As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
        The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
        At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.

        When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.

        Double Stacking.

        If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
        When doublestacked, the proms generally fade and the surface has more contrast and has better detail.

        If the field was flattened well in single mode, the field should be fairly flat in DS mode.

        There are a few subtle things that can be done to improve the system's performance.

        Make sure the area you wish to observe is in the center of the eyepiece.
        Tune the LS60T to the furthest to the right position possible with the tilt knob.
        Place the LS50F on the front and tune for the best surface detail.
        Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
        Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
        An O-ring or some felt may help if it goes more than 1/4 turn.

        You will note the surface contrast will alter. Getting better and then worse as you turn.
        There will be a point where the surface should pop a little better and the "band" almost eliminated.

        Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.

        Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
        This system is currently available on our LS100T and really works well.

        Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
        Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.

        I hope the above explains a little of what is going on.
        We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.

        Andrew Lunt
        Lunt Solar Systems LLC
        2520 N. Coyote Drive. Suite 111
        Tucson, AZ 85745
        USA
        Tel: (520) 344 7348
        Fax: (520) 344 7352
        www.luntsolarsystems.com


        Andrew Lunt
        Lunt Solar Systems LLC
        2520 N. Coyote Drive. Suite 111
        Tucson, AZ 85745
        USA
        Tel: (520) 344 7348
        Fax: (520) 344 7352
        www.luntsolarsystems.com


        ------------------------------------

        Yahoo! Groups Links
      • Emmanuel Thienpont
        Thx Andy. Like you said in a tech note somewhere a year ago you posted the same kind of info. Based on that post I decided not to go for the scope but for the
        Message 3 of 15 , Mar 27, 2009
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          Thx Andy.

          Like you said in a tech note somewhere a year ago you posted the same kind of info.
          Based on that post I decided not to go for the scope but for the double stack front filters.
          It turned out a good decision for me.

          The banding contrast issue, exist also in the front filters and the best region to look is indeed in the center with one eyepiece.
          Double stacking gives wonderful detail on the surface of the sun, but also increases the visibility of
          the bigger but fainter proms as well.

          Putting a bino on a double stack changes things dramatically. All of a sudden you get far more contrast and the banding disappears magically almost entirely . Even in a 25mm eyepiece you see proms that weren't visible with one eyepiece.
          This is experienced with double stack front filters. I hope to test this very soon also on a LS60T and see what difference it gives there.

          Greetz
          Manu
           

          On Thu, Mar 26, 2009 at 5:42 PM, <kflor@...> wrote:

          From Andrew, with his permission.

          Hi Ken,

          First I will address the "banding" issue that you mention in your e-mails.

          Internal etalon systems have a few compromises when compared to external front mounted etalons.
          The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
          As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.

          The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
          However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
          The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
          This has the effect of a slight bird shape (with regard to contrast) across the field.
          As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
          We have optimized for as flat a field as physics will allow.

          The other issue is due to the fact that our internal etalons are tiltable.

          Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
          Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.

          I have replied to many e-mails from customers who state that the tuner does very little.
          They are absolutely correct.
          The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
          The tilt mechanism does not work like the tilt mechanism on the front of a system.

          The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.

          When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
          As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
          The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
          At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.

          When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.

          Double Stacking.

          If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
          When doublestacked, the proms generally fade and the surface has more contrast and has better detail.

          If the field was flattened well in single mode, the field should be fairly flat in DS mode.

          There are a few subtle things that can be done to improve the system's performance.

          Make sure the area you wish to observe is in the center of the eyepiece.
          Tune the LS60T to the furthest to the right position possible with the tilt knob.
          Place the LS50F on the front and tune for the best surface detail.
          Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
          Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
          An O-ring or some felt may help if it goes more than 1/4 turn.

          You will note the surface contrast will alter. Getting better and then worse as you turn.
          There will be a point where the surface should pop a little better and the "band" almost eliminated.

          Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.

          Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
          This system is currently available on our LS100T and really works well.

          Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
          Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.

          I hope the above explains a little of what is going on.
          We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.

          Andrew Lunt
          Lunt Solar Systems LLC
          2520 N. Coyote Drive. Suite 111
          Tucson, AZ 85745
          USA
          Tel: (520) 344 7348
          Fax: (520) 344 7352
          www.luntsolarsystems.com

          Andrew Lunt
          Lunt Solar Systems LLC
          2520 N. Coyote Drive. Suite 111
          Tucson, AZ 85745
          USA
          Tel: (520) 344 7348
          Fax: (520) 344 7352
          www.luntsolarsystems.com


        • Emmanuel Thienpont
          Hi, The reason why we get such a contrast boost with bino s has purely to see how our brains function. I m not a doctor in medicine (so don t ask me to
          Message 4 of 15 , Mar 27, 2009
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            Hi,

            The reason why we get such a contrast boost with bino's has purely to see how our brains function.
            I'm not a doctor in medicine (so don't ask me to explain), but I got a friend who's wife is a doctor and also an amateur.

            Greetz
            Manu

            On Fri, Mar 27, 2009 at 10:18 AM, Emmanuel Thienpont <emmanuel.thienpont@...> wrote:
            Thx Andy.

            Like you said in a tech note somewhere a year ago you posted the same kind of info.
            Based on that post I decided not to go for the scope but for the double stack front filters.
            It turned out a good decision for me.

            The banding contrast issue, exist also in the front filters and the best region to look is indeed in the center with one eyepiece.
            Double stacking gives wonderful detail on the surface of the sun, but also increases the visibility of
            the bigger but fainter proms as well.

            Putting a bino on a double stack changes things dramatically. All of a sudden you get far more contrast and the banding disappears magically almost entirely . Even in a 25mm eyepiece you see proms that weren't visible with one eyepiece.
            This is experienced with double stack front filters. I hope to test this very soon also on a LS60T and see what difference it gives there.

            Greetz
            Manu

             

            On Thu, Mar 26, 2009 at 5:42 PM, <kflor@...> wrote:

            From Andrew, with his permission.

            Hi Ken,

            First I will address the "banding" issue that you mention in your e-mails.

            Internal etalon systems have a few compromises when compared to external front mounted etalons.
            The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
            As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.

            The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
            However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
            The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
            This has the effect of a slight bird shape (with regard to contrast) across the field.
            As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
            We have optimized for as flat a field as physics will allow.

            The other issue is due to the fact that our internal etalons are tiltable.

            Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
            Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.

            I have replied to many e-mails from customers who state that the tuner does very little.
            They are absolutely correct.
            The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
            The tilt mechanism does not work like the tilt mechanism on the front of a system.

            The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.

            When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
            As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
            The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
            At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.

            When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.

            Double Stacking.

            If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
            When doublestacked, the proms generally fade and the surface has more contrast and has better detail.

            If the field was flattened well in single mode, the field should be fairly flat in DS mode.

            There are a few subtle things that can be done to improve the system's performance.

            Make sure the area you wish to observe is in the center of the eyepiece.
            Tune the LS60T to the furthest to the right position possible with the tilt knob.
            Place the LS50F on the front and tune for the best surface detail.
            Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
            Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
            An O-ring or some felt may help if it goes more than 1/4 turn.

            You will note the surface contrast will alter. Getting better and then worse as you turn.
            There will be a point where the surface should pop a little better and the "band" almost eliminated.

            Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.

            Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
            This system is currently available on our LS100T and really works well.

            Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
            Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.

            I hope the above explains a little of what is going on.
            We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.

            Andrew Lunt
            Lunt Solar Systems LLC
            2520 N. Coyote Drive. Suite 111
            Tucson, AZ 85745
            USA
            Tel: (520) 344 7348
            Fax: (520) 344 7352
            www.luntsolarsystems.com

            Andrew Lunt
            Lunt Solar Systems LLC
            2520 N. Coyote Drive. Suite 111
            Tucson, AZ 85745
            USA
            Tel: (520) 344 7348
            Fax: (520) 344 7352
            www.luntsolarsystems.com



          • John
            When I first decided I would go to a Lunt, I was thinking of only the complete telescope system. I ve since changed my mind. I think I ll go with a filter
            Message 5 of 15 , Mar 27, 2009
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              When I first decided I would go to a Lunt, I was thinking of only the complete telescope system.

              I've since changed my mind. I think I'll go with a filter system and commit a refractor to the job.

              The LS75F gets too far beyond my budget, so it looks like the LS50F.
              Not a lot of aperture and it'll end up a little more expensive route, but I think it also offers a lot more options.

              From what I've been reading, it sounds like one could expect better performance going that way.

              John
            • Donn
              Hi Andy & all: Wow - nice explanation. This is the stuff we desperately need as users - detailed explanations of how to tune these scopes and filters and
              Message 6 of 15 , Mar 27, 2009
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                Hi Andy & all:

                Wow - nice explanation. This is the stuff we desperately need as users - detailed explanations of how to tune these scopes and filters and squeeze the best performance out of them. If there's more gems like this, they should either be put into the appendix of the manuals or collected as 'application notes' or similar and posted on both the Lunt website and the group files section.

                Thanks, and I hope there's some more to come :-)

                Peace & blessings,
                Donn Williams / donnwtwo

                --- In luntsolar@yahoogroups.com, kflor@... wrote:
                >
                > From Andrew, with his permission.
                >
                > Hi Ken,
                >
                > First I will address the "banding" issue that you mention in your e-mails.
                >
                > Internal etalon systems have a few compromises when compared to external front mounted etalons.
                > The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution....[snip]...
              • Brian Colville
                John... I have the LF50/B1200 (only single stack) used on a William Optics 66, and an old Celestron C102 refractor. AS an example of the small aperatures
                Message 7 of 15 , Mar 27, 2009
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                  John...

                  I have the LF50/B1200 (only single stack) used on a William Optics 66, and an old Celestron C102 refractor. AS an example of the small aperatures ability, look in my folder (Maple Ridge Observatory) here for examples. I have not run many throught he C102 due to a mounting problem I have, but I can set up temporarily and get some images.

                  If you have anyquestions, send them my way.

                  Brian
                • David Arditti
                  This message is most helpful as it answers questions that I and others have put about the tuning behavour of the LS60T. It would be helpful if something like
                  Message 8 of 15 , Mar 28, 2009
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                    This message is most helpful as it answers questions that I and others have put about the tuning behavour of the LS60T.

                    It would be helpful if something like this, at least the parts about the tuning, were in the manual you get with the scope. The wording in the manual kind of leads you to expect something different, and this is what leads to the queries - Andrew saying he has answered "many" emails on this - this is the problem: we wonder if our scopes are defective with this tuning behaviour with the knob very loose in one part of its travel, and no improvement in the image as you tighten it up.

                    I note, though, still in this, the confusing ambiguity about the meaning of the phrase "turn of the knob" when discussing the tuner. I think it means "one push of the finger from one side of the aperture to the other", but it might be thought to mean "360 degree rotation".

                    Another query I had about an asymmetrical reflection on the object glass was answered by Lunt Europe. I thought this might indicate miscollimation, but it does not.
                    I quote:

                    " The reflecting spot must be off axis because it is reflectied from the tild sitting ERF in front of the Etalon, the tilt position is normal and must be told to keep ghosting away, its tilted on any manufacturers product, Lunt, Coronado, DayStar, Solarscope" LUNT EUROPE

                    David

                    --- In luntsolar@yahoogroups.com, kflor@... wrote:
                    >
                    > From Andrew, with his permission.
                    >
                    >
                    > Hi Ken,
                    >
                    > First I will address the "banding" issue that you mention in your e-mails.
                    >
                    > Internal etalon systems have a few compromises when compared to external front mounted etalons.
                    > The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
                    > As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.
                    >
                    > The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
                    > However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
                    > The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
                    > This has the effect of a slight bird shape (with regard to contrast) across the field.
                    > As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
                    > We have optimized for as flat a field as physics will allow.
                    >
                    > The other issue is due to the fact that our internal etalons are tiltable.
                    >
                    > Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
                    > Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.
                    >
                    > I have replied to many e-mails from customers who state that the tuner does very little.
                    > They are absolutely correct.
                    > The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
                    > The tilt mechanism does not work like the tilt mechanism on the front of a system.
                    >
                    > The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.
                    >
                    > When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
                    > As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
                    > The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
                    > At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.
                    >
                    > When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.
                    >
                    > Double Stacking.
                    >
                    > If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
                    > When doublestacked, the proms generally fade and the surface has more contrast and has better detail.
                    >
                    > If the field was flattened well in single mode, the field should be fairly flat in DS mode.
                    >
                    > There are a few subtle things that can be done to improve the system's performance.
                    >
                    > Make sure the area you wish to observe is in the center of the eyepiece.
                    > Tune the LS60T to the furthest to the right position possible with the tilt knob.
                    > Place the LS50F on the front and tune for the best surface detail.
                    > Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
                    > Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
                    > An O-ring or some felt may help if it goes more than 1/4 turn.
                    >
                    > You will note the surface contrast will alter. Getting better and then worse as you turn.
                    > There will be a point where the surface should pop a little better and the "band" almost eliminated.
                    >
                    > Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.
                    >
                    > Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
                    > This system is currently available on our LS100T and really works well.
                    >
                    > Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
                    > Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.
                    >
                    > I hope the above explains a little of what is going on.
                    > We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.
                    >
                    > Andrew Lunt
                    > Lunt Solar Systems LLC
                    > 2520 N. Coyote Drive. Suite 111
                    > Tucson, AZ 85745
                    > USA
                    > Tel: (520) 344 7348
                    > Fax: (520) 344 7352
                    > www.luntsolarsystems.com
                    >
                    >
                    > Andrew Lunt
                    > Lunt Solar Systems LLC
                    > 2520 N. Coyote Drive. Suite 111
                    > Tucson, AZ 85745
                    > USA
                    > Tel: (520) 344 7348
                    > Fax: (520) 344 7352
                    > www.luntsolarsystems.com
                    >
                  • Chuck Gulker
                    Lunt should have someone who knows how to write user manuals....well write the user manual. It would certainly help folks get more out of their scopes. Chuck
                    Message 9 of 15 , Mar 28, 2009
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                      Lunt should have someone who knows how to write user manuals....well write the user manual.  It would certainly help folks get more out of their scopes. 
                       
                      Chuck


                      Quick access to Windows Live and your favorite MSN content with Internet Explorer 8.
                    • Gene Baraff
                      ... The second of the two sentences above: Can anybody explain just what that means? The meaning of everything else Andy Lunt explained in the message
                      Message 10 of 15 , Apr 2 5:26 PM
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                        --- In luntsolar@yahoogroups.com, kflor@... wrote:
                        >
                        > From Andrew, with his permission.
                        >
                        > Hi Ken,
                        >
                        > *********** snipped ************
                        > However, there are always some off axis light rays that can
                        > never be brought perpendicular to the etalon.
                        >
                        > The optimization is done such that the field is collimated
                        > at about 70-80% of the aperture of the etalon.
                        >
                        > *********** snippped ***********
                        >
                        The second of the two sentences above: Can anybody explain just what that means? The meaning of everything else Andy Lunt explained in the message quoted above is crystal clear, but this one sentence leaves me missing its meaning.

                        Can anyone help?

                        Thanks in advance.

                        Gene Baraff
                      • howieglatter
                        ... O.K., I ll take a schott at it : it means that the light rays which pass through 70% to 80% the etalon s active area are parallel to within whatever Andy s
                        Message 11 of 15 , Apr 3 4:01 AM
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                          "Gene Baraff" wrote:

                          > > . . The optimization is done such that the field is collimated
                          > > at about 70-80% of the aperture of the etalon.

                          > . .Can anybody explain just what that means?

                          O.K., I'll take a schott at it : it means that the light rays which pass through 70% to 80% the etalon's active area are parallel to within whatever Andy's tolerance is, implying the 20% to 30% of the lght rays are not. Etalons require parallel (collimated) light rays to work properly.

                          H.
                        • Emmanuel Thienpont
                          Hi, This afternoon I had the chance to look through a LS60T single stack. It was one with serial nr : 20093.. (forgot the last numbers). So this one should
                          Message 12 of 15 , Apr 5 1:43 PM
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                            Hi,

                            This afternoon I had the chance to look through a LS60T single stack.
                            It was one with serial nr : 20093.. (forgot the last numbers). So this one should have
                            the new Ethalon filter build in.
                            I can't compare to a 2008 manufactured LS60T but only with two 50mm front filters I own (made in 2008).
                            To be honest, I don't see any difference, both have still banding. You could easy see this by moving the
                            sun through the field of view (20mm plössel Meade eyepiece). There was a nice protuberance visible and you could see it very well, and when you moved
                            the sun through the field of view  (back and forward) it appeared and disappeared completely (moved only a bit out of center, so not fully to the edge).

                            Conclusion for now (after one test), and I can't say anything about 2008 made LS60T, but the LS60T made in 2009 (with new Ethalon) works as fine as a
                            50mm front filter made in 2008. I liked the image I saw this afternoon.

                            The only disadvantage of a LS60T for me was that you aren't able to use a bino without barlow's or glasspath correctors.
                            I even connected the bino on the T-wire of the Lunt prism, but still this wasn't giving enough in-travel.
                            I prefere to view the sun without those extra tools.

                            Then I putted my 50mm front filter on it and after some tweaking I saw a nice double stacked image.
                            Again the same image that I'm used of with my double stack 50mm front filters with one eyepiece.
                            I mostly use my bino and then you get far more contrast just by using two eyes and a piece of black cloth over your head.

                            Another point I have tested this afternoon is the margin of change (how much difference in your view when turning on the tuning wheel) with a LS60T and a front filter. Like Andy described : on a scope system
                            the margin of change is far less then on a front filter. And yes, this was clearly visible.

                            Greetz
                            Manu














                            On Thu, Mar 26, 2009 at 6:42 PM, <kflor@...> wrote:

                            From Andrew, with his permission.

                            Hi Ken,

                            First I will address the "banding" issue that you mention in your e-mails.

                            Internal etalon systems have a few compromises when compared to external front mounted etalons.
                            The main reason for an internal system is the reduced cost of the solar scope while providing a larger aperture which will allow for better resolution.
                            As I have stated in a few previous tech notes, the internal etalon will compromise slightly from a few issues.

                            The collimation system in our LS60T is optimized to the best of our ability at the 656nm wavelength.
                            However, there are always some off axis light rays that can never be brought perpendicular to the etalon.
                            The optimization is done such that the field is collimated at about 70-80% of the aperture of the etalon.
                            This has the effect of a slight bird shape (with regard to contrast) across the field.
                            As etalons improve, this bird effect will become more apparent for the internal system. Hence the reason we general try to keep internal etalons at about 0 .7-0.8 angstroms.
                            We have optimized for as flat a field as physics will allow.

                            The other issue is due to the fact that our internal etalons are tiltable.

                            Competitive products do not allow for any internal tilt. The etalon is fixed at the factory and there is no additional tuning capability by the customer.
                            Etalons are air spaced. The air inside the gap of the etalon has a refractive index tied to barometric pressure and altitude. As these things change, the center wavelength of the etalon will change. The design of an etalon is tied to the refractive index of the gap. In our case the gap is air. In solid etalons the gap is glass.

                            I have replied to many e-mails from customers who state that the tuner does very little.
                            They are absolutely correct.
                            The internal etalon is tuned very precisely at the factory to a position that is as perpendicular to the optical train as possible. Thus reducing the off axis errors that may be created across of the field to a minimum.
                            The tilt mechanism does not work like the tilt mechanism on the front of a system.

                            The tilt mechanism is there to allow for very minor changes to the center wavelength to compensate for changes in air pressure and altitude. Some Doppler shifting can be done but due to the fact that Doppler shifting is done by tilting the etalon plane at an angle you will notice a "banding" effect across image. As you tilt more, the banding effect will tighten.

                            When the tilt of the LS60T internal etalon is all the way to the right when at the eyepiece, the mechanism will be loose. This is the point where the tilt rod is disengaged from the etalon housing to assure that the etalon is sitting flat with no mechanical influence.
                            As the tilt knob is moved to the left, it will engage the etalon housing. The etalon should be, or come on band, within 1 turn of the knob. If you are using the system between 1500 and 3500 feet, no tilt may be needed. We provide far more range than necassary due to mechnical tolerances of the tilt parts.
                            The tilt will allow the user to fine tune the center wavelength and flatten the field. This works well at lower magnifications.
                            At higher magnifications, tilting the etalon will tighten that band I talked about earlier. I cannot explain the physics of the ray tracing in an e-mail but the result is a slight improvement of the contrast in a band across the etalon which is parallel to the etalon pivot point. This may allow for a slightly better view of small surface detail. At higher magnifications the system can be tweaked to look at small surface detail. The lost contrast will not be visible.

                            When the system is being used for full disk images and the tilt is adjusted the Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of the system outside these parameters will increase contrast at what people refer to as a sweet spot at the loss of contrast elsewhere.

                            Double Stacking.

                            If you doublestack the LS60T, you are reducing the bandpass to about 0.55 Angstroms.
                            When doublestacked, the proms generally fade and the surface has more contrast and has better detail.

                            If the field was flattened well in single mode, the field should be fairly flat in DS mode.

                            There are a few subtle things that can be done to improve the system's performance.

                            Make sure the area you wish to observe is in the center of the eyepiece.
                            Tune the LS60T to the furthest to the right position possible with the tilt knob.
                            Place the LS50F on the front and tune for the best surface detail.
                            Very VERY slowly move the LS60T tilt knob to the left. It will not take much (<1/4 turn)
                            Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall off! It doesn't have to go more than 1/2 a turn).
                            An O-ring or some felt may help if it goes more than 1/4 turn.

                            You will note the surface contrast will alter. Getting better and then worse as you turn.
                            There will be a point where the surface should pop a little better and the "band" almost eliminated.

                            Because the etalon on the front is tilted and the etalon inside is tilted we do have some ray angles to deal with. It is possible to re-optimize the system with a little rotation.

                            Lunt Solar are moving forward on a patent pending design for an internal pressure tuned system.
                            This system is currently available on our LS100T and really works well.

                            Because we place the etalon internally in the normal position we can really optimize the rays with the collimating system.
                            Air pressure allows us to increase and decrease the refractive index of the air gap without tilt. This allows for true Doppler shifting toward and away from the user instead of up and down.

                            I hope the above explains a little of what is going on.
                            We have worked very hard to optimize an internal system in order to bring it to a price point where people can enjoy a 60mm aperture. Alternate front mount systems do cost more due to the larger etalon, but as I have described above, most of the compromises are gone. Air tuning, off course, will take internal systems to a whole new level of performance.

                            Andrew Lunt
                            Lunt Solar Systems LLC
                            2520 N. Coyote Drive. Suite 111
                            Tucson, AZ 85745
                            USA
                            Tel: (520) 344 7348
                            Fax: (520) 344 7352
                            www.luntsolarsystems.com

                            Andrew Lunt
                            Lunt Solar Systems LLC
                            2520 N. Coyote Drive. Suite 111
                            Tucson, AZ 85745
                            USA
                            Tel: (520) 344 7348
                            Fax: (520) 344 7352
                            www.luntsolarsystems.com


                          • jacquesfrr
                            Hello Emmanuel, You said : This afternoon I had the chance to look through a LS60T single stack. It was one with serial nr : 20093.. (forgot the last
                            Message 13 of 15 , Apr 6 12:38 AM
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                              Hello Emmanuel,

                              You said :
                              "This afternoon I had the chance to look through a LS60T single stack.
                              It was one with serial nr : 20093.. (forgot the last numbers). So this one should have the new Ethalon filter build in.
                              I can't compare to a 2008 manufactured LS60T but only with two 50mm front filters I own (made in 2008).
                              To be honest, I don't see any difference, both have still banding. You could easy see this by moving the sun through the field of view (20mm plössel Meade eyepiece). There was a nice protuberance visible and you could see it very well, and when you moved the sun through the field of view (back and forward) it appeared and disappeared completely (moved only a bit out of center, so not fully to the edge)."

                              Emmanuel, was it a LS60T BF600 or BF1200 ? Do you remember if the Halpha area was rather centered in the field of view ? I own a LST60T-Ha BF1200 and last saturday I did the same test with a 20mm Plossl. The H-alpha area is not at all centered, it is largely off-axis. So I think my system has a collimation issue. I wonder if something can be done to fix this issue.

                              Jacques
                            • Emmanuel Thienpont
                              Hi Jacques, It was a LS60T BF600 and the H-alfa region was quite centered. I have a BF1200 so maybe next week when I m on holiday and wheather is ok, I can do
                              Message 14 of 15 , Apr 6 12:50 AM
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                                Hi Jacques,

                                It was a LS60T BF600 and the H-alfa region was quite centered.
                                I have a BF1200 so maybe next week when I'm on holiday and wheather is ok, I can do a test
                                with a BF1200 if you want.
                                Let me know.

                                Greetz
                                Manu

                                On Mon, Apr 6, 2009 at 9:38 AM, jacquesfrr <jacques-gorry@...> wrote:

                                Hello Emmanuel,

                                You said :

                                "This afternoon I had the chance to look through a LS60T single stack.
                                It was one with serial nr : 20093.. (forgot the last numbers). So this one should have the new Ethalon filter build in.
                                I can't compare to a 2008 manufactured LS60T but only with two 50mm front filters I own (made in 2008).
                                To be honest, I don't see any difference, both have still banding. You could easy see this by moving the sun through the field of view (20mm plössel Meade eyepiece). There was a nice protuberance visible and you could see it very well, and when you moved the sun through the field of view (back and forward) it appeared and disappeared completely (moved only a bit out of center, so not fully to the edge)."

                                Emmanuel, was it a LS60T BF600 or BF1200 ? Do you remember if the Halpha area was rather centered in the field of view ? I own a LST60T-Ha BF1200 and last saturday I did the same test with a 20mm Plossl. The H-alpha area is not at all centered, it is largely off-axis. So I think my system has a collimation issue. I wonder if something can be done to fix this issue.

                                Jacques


                              • jacquesfrr
                                Thank you Emmanuel, If the Halpha is centered with a BF600, it will be centered too with a BF1200. So, thank you but no need to do another test with a BF1200,
                                Message 15 of 15 , Apr 6 10:30 AM
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                                  Thank you Emmanuel,

                                  If the Halpha is centered with a BF600, it will be centered too with a BF1200. So, thank you but no need to do another test with a BF1200, unless it is with another LS60T.

                                  Jacques


                                  --- In luntsolar@yahoogroups.com, Emmanuel Thienpont <emmanuel.thienpont@...> wrote:
                                  >
                                  > Hi Jacques,
                                  >
                                  > It was a LS60T BF600 and the H-alfa region was quite centered.
                                  > I have a BF1200 so maybe next week when I'm on holiday and wheather is ok, I
                                  > can do a test
                                  > with a BF1200 if you want.
                                  > Let me know.
                                  >
                                  > Greetz
                                  > Manu
                                  >
                                  > On Mon, Apr 6, 2009 at 9:38 AM, jacquesfrr <jacques-gorry@...> wrote:
                                  >
                                  > > Hello Emmanuel,
                                  > >
                                  > > You said :
                                  > > "This afternoon I had the chance to look through a LS60T single stack.
                                  > > It was one with serial nr : 20093.. (forgot the last numbers). So this one
                                  > > should have the new Ethalon filter build in.
                                  > > I can't compare to a 2008 manufactured LS60T but only with two 50mm front
                                  > > filters I own (made in 2008).
                                  > > To be honest, I don't see any difference, both have still banding. You
                                  > > could easy see this by moving the sun through the field of view (20mm
                                  > > plössel Meade eyepiece). There was a nice protuberance visible and you could
                                  > > see it very well, and when you moved the sun through the field of view (back
                                  > > and forward) it appeared and disappeared completely (moved only a bit out of
                                  > > center, so not fully to the edge)."
                                  > >
                                  > > Emmanuel, was it a LS60T BF600 or BF1200 ? Do you remember if the Halpha
                                  > > area was rather centered in the field of view ? I own a LST60T-Ha BF1200 and
                                  > > last saturday I did the same test with a 20mm Plossl. The H-alpha area is
                                  > > not at all centered, it is largely off-axis. So I think my system has a
                                  > > collimation issue. I wonder if something can be done to fix this issue.
                                  > >
                                  > > Jacques
                                  > >
                                  > >
                                  > >
                                  >
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