Loading ...
Sorry, an error occurred while loading the content.

Re: [tmboptical] Final squareness/lens test. Problem found

Expand Messages
  • Markus Ludes
    Domique, as I just told you in privat mail, forget the idea you have had. If you rotate the lens cell, you can do it only if you unlock it from the thread,
    Message 1 of 18 , Aug 1 12:55 AM
    • 0 Attachment
      Domique, as I just told you in privat mail, forget the idea you have had. If you rotate the lens cell, you can do it only if you unlock it from the thread, than you get play in the threadsa between cell and tube and you have a working tilt. Do what I told you, make a laser alignment test to find out if focuser and tube is really square

      best wishes

      Markus
      ----- Original Message -----
      From: digidodi
      To: tmboptical@yahoogroups.com
      Sent: Friday, August 01, 2003 1:49 AM
      Subject: [tmboptical] Final squareness/lens test. Problem found


      Well, I did one more test. I rotated the lenscell 90 degrees and the
      error rotates with it.

      So the error is in the lens itself. Although it is spectacularly good
      in the center for Mars, I intended to use the scope for deep-sky
      photography, so I will probably need to swap lenses. Too bad, it had
      lambda 1/11.

      A slight problem of quality control in lens cell or mounting of
      elements?

      What do you suspect Thomas? The lens or the cell. Can I do something
      myself or better send it back?

      Dodi


      Yahoo! Groups Sponsor
      ADVERTISEMENT




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



      Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



      [Non-text portions of this message have been removed]
    • digidodi
      Markus You are wrong. With a 90 degree rotation in thread, there is still absolutely no play with the lens cell in the tube, and no tilt. I tried but cannot
      Message 2 of 18 , Aug 1 1:11 AM
      • 0 Attachment
        Markus

        You are wrong. With a 90 degree rotation in thread, there is still
        absolutely no play with the lens cell in the tube, and no tilt. I
        tried but cannot move the lenscell in any other direction but turning
        it.

        Rotating the lens by 90 degrees produces exactly the same error star
        for star, aberration per aberration.

        I am sorry, it *is* the lens or the cell, or - very unlikely -
        potentially the top end machining of the tube of course.

        Dodi


        --- In tmboptical@yahoogroups.com, "Markus Ludes"
        <apm_telescopes@w...> wrote:
        > Domique, as I just told you in privat mail, forget the idea you
        have had. If you rotate the lens cell, you can do it only if you
        unlock it from the thread, than you get play in the threadsa between
        cell and tube and you have a working tilt. Do what I told you, make a
        laser alignment test to find out if focuser and tube is really square
        >
        > best wishes
        >
        > Markus
        > ----- Original Message -----
        > From: digidodi
        > To: tmboptical@yahoogroups.com
        > Sent: Friday, August 01, 2003 1:49 AM
        > Subject: [tmboptical] Final squareness/lens test. Problem found
        >
        >
        > Well, I did one more test. I rotated the lenscell 90 degrees and
        the
        > error rotates with it.
        >
        > So the error is in the lens itself. Although it is spectacularly
        good
        > in the center for Mars, I intended to use the scope for deep-sky
        > photography, so I will probably need to swap lenses. Too bad, it
        had
        > lambda 1/11.
        >
        > A slight problem of quality control in lens cell or mounting of
        > elements?
        >
        > What do you suspect Thomas? The lens or the cell. Can I do
        something
        > myself or better send it back?
        >
        > Dodi
        >
        >
        > Yahoo! Groups Sponsor
        > ADVERTISEMENT
        >
        >
        >
        >
        > To unsubscribe from this group, send an email to:
        > tmboptical-unsubscribe@egroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
        Service.
        >
        >
        >
        > [Non-text portions of this message have been removed]
      • Markus Ludes
        Hey I installed many lenses in such tubes and all have play . If your lens show on axis at high power zero coma, that it is for shure not the lens best wishes
        Message 3 of 18 , Aug 1 1:45 AM
        • 0 Attachment
          Hey I installed many lenses in such tubes and all have play . If your lens show on axis at high power zero coma, that it is for shure not the lens

          best wishes
          Markus
          ----- Original Message -----
          From: digidodi
          To: tmboptical@yahoogroups.com
          Sent: Friday, August 01, 2003 10:11 AM
          Subject: [tmboptical] Re: Final squareness/lens test. Problem found


          Markus

          You are wrong. With a 90 degree rotation in thread, there is still
          absolutely no play with the lens cell in the tube, and no tilt. I
          tried but cannot move the lenscell in any other direction but turning
          it.

          Rotating the lens by 90 degrees produces exactly the same error star
          for star, aberration per aberration.

          I am sorry, it *is* the lens or the cell, or - very unlikely -
          potentially the top end machining of the tube of course.

          Dodi


          --- In tmboptical@yahoogroups.com, "Markus Ludes"
          <apm_telescopes@w...> wrote:
          > Domique, as I just told you in privat mail, forget the idea you
          have had. If you rotate the lens cell, you can do it only if you
          unlock it from the thread, than you get play in the threadsa between
          cell and tube and you have a working tilt. Do what I told you, make a
          laser alignment test to find out if focuser and tube is really square
          >
          > best wishes
          >
          > Markus
          > ----- Original Message -----
          > From: digidodi
          > To: tmboptical@yahoogroups.com
          > Sent: Friday, August 01, 2003 1:49 AM
          > Subject: [tmboptical] Final squareness/lens test. Problem found
          >
          >
          > Well, I did one more test. I rotated the lenscell 90 degrees and
          the
          > error rotates with it.
          >
          > So the error is in the lens itself. Although it is spectacularly
          good
          > in the center for Mars, I intended to use the scope for deep-sky
          > photography, so I will probably need to swap lenses. Too bad, it
          had
          > lambda 1/11.
          >
          > A slight problem of quality control in lens cell or mounting of
          > elements?
          >
          > What do you suspect Thomas? The lens or the cell. Can I do
          something
          > myself or better send it back?
          >
          > Dodi
          >
          >
          > Yahoo! Groups Sponsor
          > ADVERTISEMENT
          >
          >
          >
          >
          > To unsubscribe from this group, send an email to:
          > tmboptical-unsubscribe@egroups.com
          >
          >
          >
          > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
          Service.
          >
          >
          >
          > [Non-text portions of this message have been removed]


          Yahoo! Groups Sponsor
          ADVERTISEMENT




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



          Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



          [Non-text portions of this message have been removed]
        • digidodi
          Unless as I suspect the error is lateral in the lens or cell. Then you would still have good on axis performance, but as all photographers know, if you move
          Message 4 of 18 , Aug 1 10:31 AM
          • 0 Attachment
            Unless as I suspect the error is lateral in the lens or cell. Then
            you would still have good on axis performance, but as all
            photographers know, if you move the camera laterally away from the
            axis for one reason or another, you get uneven aberation because you
            are putting part of the image zone outside the aberation free image
            circle. I think this is what's happening.

            Anyway, for the record, Markus accepted to have me send the refractor
            to him and he will test it. I have also had a new tube send to him by
            the tube manufacturer. We'll see, and I'll post the outcome here.

            We bet for a bottle of Champagne that the error is in the lens (my
            bet) or tube (Markus). If I am wrong, I will admit it without problem.

            But Thomas, could you comment if lateral error is a potential problem
            in lens or cell assembly and could explain what I see?

            Dodi


            --- In tmboptical@yahoogroups.com, "Markus Ludes"
            <apm_telescopes@w...> wrote:
            > Hey I installed many lenses in such tubes and all have play . If
            your lens show on axis at high power zero coma, that it is for shure
            not the lens
            >
            > best wishes
            > Markus
            > ----- Original Message -----
            > From: digidodi
            > To: tmboptical@yahoogroups.com
            > Sent: Friday, August 01, 2003 10:11 AM
            > Subject: [tmboptical] Re: Final squareness/lens test. Problem
            found
            >
            >
            > Markus
            >
            > You are wrong. With a 90 degree rotation in thread, there is
            still
            > absolutely no play with the lens cell in the tube, and no tilt. I
            > tried but cannot move the lenscell in any other direction but
            turning
            > it.
            >
            > Rotating the lens by 90 degrees produces exactly the same error
            star
            > for star, aberration per aberration.
            >
            > I am sorry, it *is* the lens or the cell, or - very unlikely -
            > potentially the top end machining of the tube of course.
            >
            > Dodi
            >
            >
            > --- In tmboptical@yahoogroups.com, "Markus Ludes"
            > <apm_telescopes@w...> wrote:
            > > Domique, as I just told you in privat mail, forget the idea you
            > have had. If you rotate the lens cell, you can do it only if you
            > unlock it from the thread, than you get play in the threadsa
            between
            > cell and tube and you have a working tilt. Do what I told you,
            make a
            > laser alignment test to find out if focuser and tube is really
            square
            > >
            > > best wishes
            > >
            > > Markus
            > > ----- Original Message -----
            > > From: digidodi
            > > To: tmboptical@yahoogroups.com
            > > Sent: Friday, August 01, 2003 1:49 AM
            > > Subject: [tmboptical] Final squareness/lens test. Problem
            found
            > >
            > >
            > > Well, I did one more test. I rotated the lenscell 90 degrees
            and
            > the
            > > error rotates with it.
            > >
            > > So the error is in the lens itself. Although it is
            spectacularly
            > good
            > > in the center for Mars, I intended to use the scope for deep-
            sky
            > > photography, so I will probably need to swap lenses. Too bad,
            it
            > had
            > > lambda 1/11.
            > >
            > > A slight problem of quality control in lens cell or mounting
            of
            > > elements?
            > >
            > > What do you suspect Thomas? The lens or the cell. Can I do
            > something
            > > myself or better send it back?
            > >
            > > Dodi
            > >
            > >
            > > Yahoo! Groups Sponsor
            > > ADVERTISEMENT
            > >
            > >
            > >
            > >
            > > To unsubscribe from this group, send an email to:
            > > tmboptical-unsubscribe@egroups.com
            > >
            > >
            > >
            > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
            > Service.
            > >
            > >
            > >
            > > [Non-text portions of this message have been removed]
            >
            >
            > Yahoo! Groups Sponsor
            > ADVERTISEMENT
            >
            >
            >
            >
            > To unsubscribe from this group, send an email to:
            > tmboptical-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
            Service.
            >
            >
            >
            > [Non-text portions of this message have been removed]
          • Richard Chalfan
            ... Dodi, If by lateral error, you mean that the optical axis of the lens does not go down the center of the tube (that is, the optical axis is offset from the
            Message 5 of 18 , Aug 1 12:30 PM
            • 0 Attachment
              --- digidodi <ddierick@...> wrote:

              > Unless as I suspect the error is lateral in the lens
              > or cell. Then
              > you would still have good on axis performance, but
              > as all
              > photographers know, if you move the camera laterally
              > away from the
              > axis for one reason or another, you get uneven
              > aberation because you
              > are putting part of the image zone outside the
              > aberation free image
              > circle. I think this is what's happening.
              >
              Dodi,

              If by lateral error, you mean that the optical axis of
              the lens does not go down the center of the tube (that
              is, the optical axis is offset from the tube's
              mechanical axis, but they are parallel), then yes,
              your CCD images would look like what you posted.

              Your pictures model my earlier suggestion too. The
              aberrations on one side are more pronounced than those
              on the other side if the CCD is perpendicular to, but
              not centered on, the mechanical (and optical) axis of
              the scope.

              But if the lens is perfect and the optical axis of the
              lens is perpendicular to the CCD chip, though
              laterally offset, you should be able to see that in a
              star test.

              The Airy disk rings will only be perfectly concentric
              ON the objective's optical axis. With a laterally
              offset axis, you would see perfectly concentric rings
              off of the center of the field, and non-concentric
              rings when the star was in the middle of the field.

              The reason I earlier suggested an offset chip, is
              because that condition still gives a perfect star test
              in a perfect scope. It is the only condition I can
              think of off hand, where you get a perfect star test,
              but your CCD image is both properly focused and
              abberationally unsymmetrical.

              If the lens is tilted (the objective axis is at an
              angle to the tube's mechanical axis and to the
              eyepiece axis) then you will see an Airy disk with
              off-axis aberrations. And your CCD chip should have a
              band of good focus, going slightly out of focus on
              either side of the band.

              If the lens elements are not mounted properly within
              the cell, then you will not see a "perfect" Airy disk
              even on axis. I think it would look rather
              astigmatic.

              So your symptoms sound slightly conflicting. However,
              if the errors are small the "theoretical" symptoms may
              be hard to detect. I think sending the tube back to
              Marcus is a reasonable start. It is possible though,
              that he will find no problem with the lens or the
              tube.

              Please let us know how this turns out.

              Good luck!!!!

              Richard
              >

              __________________________________
              Do you Yahoo!?
              Yahoo! SiteBuilder - Free, easy-to-use web site design software
              http://sitebuilder.yahoo.com
            • digidodi
              Hi Richard, Thanks for your valued comments. I can surely exclude a chip offset. I tried with my AstroPhysics 155 refractor and the stars are pinpoints to the
              Message 6 of 18 , Aug 1 1:49 PM
              • 0 Attachment
                Hi Richard,

                Thanks for your valued comments.

                I can surely exclude a chip offset. I tried with my AstroPhysics 155
                refractor and the stars are pinpoints to the edge. I think it would
                show up there too otherwise. I used the same camera adapter.

                I am pretty convinced it is not tilt, for the reason you mention.
                Tilt would give gradual errors on both sides. Not assymetrical as
                this one.

                I have done the startest, but did not pay much attention yet to being
                in the center of the field exactly. That may explain the conflict. I
                will give it a try tonite before packing in the tube for shipment.

                Hopefully Markus can fix it or give another tube. Because this one is
                helas unusable for photography for the moment.

                Dodi

                --- In tmboptical@yahoogroups.com, Richard Chalfan <rchalfan@y...>
                wrote:
                >
                > --- digidodi <ddierick@h...> wrote:
                >
                > > Unless as I suspect the error is lateral in the lens
                > > or cell. Then
                > > you would still have good on axis performance, but
                > > as all
                > > photographers know, if you move the camera laterally
                > > away from the
                > > axis for one reason or another, you get uneven
                > > aberation because you
                > > are putting part of the image zone outside the
                > > aberation free image
                > > circle. I think this is what's happening.
                > >
                > Dodi,
                >
                > If by lateral error, you mean that the optical axis of
                > the lens does not go down the center of the tube (that
                > is, the optical axis is offset from the tube's
                > mechanical axis, but they are parallel), then yes,
                > your CCD images would look like what you posted.
                >
                > Your pictures model my earlier suggestion too. The
                > aberrations on one side are more pronounced than those
                > on the other side if the CCD is perpendicular to, but
                > not centered on, the mechanical (and optical) axis of
                > the scope.
                >
                > But if the lens is perfect and the optical axis of the
                > lens is perpendicular to the CCD chip, though
                > laterally offset, you should be able to see that in a
                > star test.
                >
                > The Airy disk rings will only be perfectly concentric
                > ON the objective's optical axis. With a laterally
                > offset axis, you would see perfectly concentric rings
                > off of the center of the field, and non-concentric
                > rings when the star was in the middle of the field.
                >
                > The reason I earlier suggested an offset chip, is
                > because that condition still gives a perfect star test
                > in a perfect scope. It is the only condition I can
                > think of off hand, where you get a perfect star test,
                > but your CCD image is both properly focused and
                > abberationally unsymmetrical.
                >
                > If the lens is tilted (the objective axis is at an
                > angle to the tube's mechanical axis and to the
                > eyepiece axis) then you will see an Airy disk with
                > off-axis aberrations. And your CCD chip should have a
                > band of good focus, going slightly out of focus on
                > either side of the band.
                >
                > If the lens elements are not mounted properly within
                > the cell, then you will not see a "perfect" Airy disk
                > even on axis. I think it would look rather
                > astigmatic.
                >
                > So your symptoms sound slightly conflicting. However,
                > if the errors are small the "theoretical" symptoms may
                > be hard to detect. I think sending the tube back to
                > Marcus is a reasonable start. It is possible though,
                > that he will find no problem with the lens or the
                > tube.
                >
                > Please let us know how this turns out.
                >
                > Good luck!!!!
                >
                > Richard
                > >
                >
                > __________________________________
                > Do you Yahoo!?
                > Yahoo! SiteBuilder - Free, easy-to-use web site design software
                > http://sitebuilder.yahoo.com
              • digidodi
                I tried it with a startest with a bit more care now. On axis image is good. Off axis image is *quite* symmetrical with a 7mm Nagler (I used this one because
                Message 7 of 18 , Aug 1 2:43 PM
                • 0 Attachment
                  I tried it with a startest with a bit more care now. On axis image is
                  good. Off axis image is *quite* symmetrical with a 7mm Nagler (I used
                  this one because it' a compromise between FOV and magnification), but
                  not perfect. Stars get a bit more elongated on one side than on the
                  other side of the FOV. Very hard to tell, but it is not symmetrical
                  100%.

                  Dodi
                • Markus Ludes
                  the tube arrived here. A laser test showed that the mechanical parts have been straight. A coolimation test of the lens showed both reflections to be 100%
                  Message 8 of 18 , Aug 7 11:32 PM
                  • 0 Attachment
                    the tube arrived here. A laser test showed that the mechanical parts have been straight. A coolimation test of the lens showed both reflections to be 100% concentric too, the startest used up to any power was also perfect.

                    As dominique wished I have send him back his tube with another which passed the test in same way.

                    To be honest I have no idea whats going on here, but in my opinion it cannot be the tube and it cannot be the lens, otherwise one of both must show a fault.

                    will be interested to see the new images from Dodi

                    Markus
                    ----- Original Message -----
                    From: Richard Chalfan
                    To: tmboptical@yahoogroups.com
                    Sent: Friday, August 01, 2003 9:30 PM
                    Subject: Re: [tmboptical] Re: Final squareness/lens test. Problem found



                    --- digidodi <ddierick@...> wrote:

                    > Unless as I suspect the error is lateral in the lens
                    > or cell. Then
                    > you would still have good on axis performance, but
                    > as all
                    > photographers know, if you move the camera laterally
                    > away from the
                    > axis for one reason or another, you get uneven
                    > aberation because you
                    > are putting part of the image zone outside the
                    > aberation free image
                    > circle. I think this is what's happening.
                    >
                    Dodi,

                    If by lateral error, you mean that the optical axis of
                    the lens does not go down the center of the tube (that
                    is, the optical axis is offset from the tube's
                    mechanical axis, but they are parallel), then yes,
                    your CCD images would look like what you posted.

                    Your pictures model my earlier suggestion too. The
                    aberrations on one side are more pronounced than those
                    on the other side if the CCD is perpendicular to, but
                    not centered on, the mechanical (and optical) axis of
                    the scope.

                    But if the lens is perfect and the optical axis of the
                    lens is perpendicular to the CCD chip, though
                    laterally offset, you should be able to see that in a
                    star test.

                    The Airy disk rings will only be perfectly concentric
                    ON the objective's optical axis. With a laterally
                    offset axis, you would see perfectly concentric rings
                    off of the center of the field, and non-concentric
                    rings when the star was in the middle of the field.

                    The reason I earlier suggested an offset chip, is
                    because that condition still gives a perfect star test
                    in a perfect scope. It is the only condition I can
                    think of off hand, where you get a perfect star test,
                    but your CCD image is both properly focused and
                    abberationally unsymmetrical.

                    If the lens is tilted (the objective axis is at an
                    angle to the tube's mechanical axis and to the
                    eyepiece axis) then you will see an Airy disk with
                    off-axis aberrations. And your CCD chip should have a
                    band of good focus, going slightly out of focus on
                    either side of the band.

                    If the lens elements are not mounted properly within
                    the cell, then you will not see a "perfect" Airy disk
                    even on axis. I think it would look rather
                    astigmatic.

                    So your symptoms sound slightly conflicting. However,
                    if the errors are small the "theoretical" symptoms may
                    be hard to detect. I think sending the tube back to
                    Marcus is a reasonable start. It is possible though,
                    that he will find no problem with the lens or the
                    tube.

                    Please let us know how this turns out.

                    Good luck!!!!

                    Richard
                    >

                    __________________________________
                    Do you Yahoo!?
                    Yahoo! SiteBuilder - Free, easy-to-use web site design software
                    http://sitebuilder.yahoo.com

                    Yahoo! Groups Sponsor
                    ADVERTISEMENT




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



                    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



                    [Non-text portions of this message have been removed]
                  • Markus Ludes
                    Dodi, I have an startest field part from Zeiss and visual the image is symmetrical. I know only 1 method to test more accurate than visuel the off axis
                    Message 9 of 18 , Aug 7 11:35 PM
                    • 0 Attachment
                      Dodi,

                      I have an startest field part from Zeiss and visual the image is symmetrical. I know only 1 method to test more accurate than visuel the off axis performance and that is by Zygo, but Its hart to believe that a camera can see something which the eye cannot see

                      best wishes

                      Markus
                      ----- Original Message -----
                      From: digidodi
                      To: tmboptical@yahoogroups.com
                      Sent: Friday, August 01, 2003 11:43 PM
                      Subject: [tmboptical] Re: Final squareness/lens test. Problem found



                      I tried it with a startest with a bit more care now. On axis image is
                      good. Off axis image is *quite* symmetrical with a 7mm Nagler (I used
                      this one because it' a compromise between FOV and magnification), but
                      not perfect. Stars get a bit more elongated on one side than on the
                      other side of the FOV. Very hard to tell, but it is not symmetrical
                      100%.

                      Dodi




                      Yahoo! Groups Sponsor
                      ADVERTISEMENT




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



                      Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



                      [Non-text portions of this message have been removed]
                    • digidodi
                      Well, it s not the camera either. I made pictures last night with an MK69 Intes, full frame with the D100, and in all directions the image is tacksharp. I used
                      Message 10 of 18 , Aug 8 11:04 AM
                      • 0 Attachment
                        Well, it's not the camera either. I made pictures last night with an
                        MK69 Intes, full frame with the D100, and in all directions the image
                        is tacksharp. I used the same camera and adapter. The only thing
                        which is not the same is the Televue reducer. I have now also a Borg
                        flattener to rule out the Televue.

                        It puzzles me as much as it puzzles you. I will do the test with the
                        new tube as soon as possible!

                        Dodi


                        --- In tmboptical@yahoogroups.com, "Markus Ludes"
                        <apm_telescopes@w...> wrote:
                        > the tube arrived here. A laser test showed that the mechanical
                        parts have been straight. A coolimation test of the lens showed both
                        reflections to be 100% concentric too, the startest used up to any
                        power was also perfect.
                        >
                        > As dominique wished I have send him back his tube with another
                        which passed the test in same way.
                        >
                        > To be honest I have no idea whats going on here, but in my opinion
                        it cannot be the tube and it cannot be the lens, otherwise one of
                        both must show a fault.
                        >
                        > will be interested to see the new images from Dodi
                        >
                        > Markus
                        > ----- Original Message -----
                        > From: Richard Chalfan
                        > To: tmboptical@yahoogroups.com
                        > Sent: Friday, August 01, 2003 9:30 PM
                        > Subject: Re: [tmboptical] Re: Final squareness/lens test. Problem
                        found
                        >
                        >
                        >
                        > --- digidodi <ddierick@h...> wrote:
                        >
                        > > Unless as I suspect the error is lateral in the lens
                        > > or cell. Then
                        > > you would still have good on axis performance, but
                        > > as all
                        > > photographers know, if you move the camera laterally
                        > > away from the
                        > > axis for one reason or another, you get uneven
                        > > aberation because you
                        > > are putting part of the image zone outside the
                        > > aberation free image
                        > > circle. I think this is what's happening.
                        > >
                        > Dodi,
                        >
                        > If by lateral error, you mean that the optical axis of
                        > the lens does not go down the center of the tube (that
                        > is, the optical axis is offset from the tube's
                        > mechanical axis, but they are parallel), then yes,
                        > your CCD images would look like what you posted.
                        >
                        > Your pictures model my earlier suggestion too. The
                        > aberrations on one side are more pronounced than those
                        > on the other side if the CCD is perpendicular to, but
                        > not centered on, the mechanical (and optical) axis of
                        > the scope.
                        >
                        > But if the lens is perfect and the optical axis of the
                        > lens is perpendicular to the CCD chip, though
                        > laterally offset, you should be able to see that in a
                        > star test.
                        >
                        > The Airy disk rings will only be perfectly concentric
                        > ON the objective's optical axis. With a laterally
                        > offset axis, you would see perfectly concentric rings
                        > off of the center of the field, and non-concentric
                        > rings when the star was in the middle of the field.
                        >
                        > The reason I earlier suggested an offset chip, is
                        > because that condition still gives a perfect star test
                        > in a perfect scope. It is the only condition I can
                        > think of off hand, where you get a perfect star test,
                        > but your CCD image is both properly focused and
                        > abberationally unsymmetrical.
                        >
                        > If the lens is tilted (the objective axis is at an
                        > angle to the tube's mechanical axis and to the
                        > eyepiece axis) then you will see an Airy disk with
                        > off-axis aberrations. And your CCD chip should have a
                        > band of good focus, going slightly out of focus on
                        > either side of the band.
                        >
                        > If the lens elements are not mounted properly within
                        > the cell, then you will not see a "perfect" Airy disk
                        > even on axis. I think it would look rather
                        > astigmatic.
                        >
                        > So your symptoms sound slightly conflicting. However,
                        > if the errors are small the "theoretical" symptoms may
                        > be hard to detect. I think sending the tube back to
                        > Marcus is a reasonable start. It is possible though,
                        > that he will find no problem with the lens or the
                        > tube.
                        >
                        > Please let us know how this turns out.
                        >
                        > Good luck!!!!
                        >
                        > Richard
                        > >
                        >
                        > __________________________________
                        > Do you Yahoo!?
                        > Yahoo! SiteBuilder - Free, easy-to-use web site design software
                        > http://sitebuilder.yahoo.com
                        >
                        > Yahoo! Groups Sponsor
                        > ADVERTISEMENT
                        >
                        >
                        >
                        >
                        > To unsubscribe from this group, send an email to:
                        > tmboptical-unsubscribe@egroups.com
                        >
                        >
                        >
                        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                        Service.
                        >
                        >
                        >
                        > [Non-text portions of this message have been removed]
                      • Richard Chalfan
                        Dodi, ... I think the reducer is an important part of the problem. The following things come to mind. 1. The reducer is almost at the focal plane. So it
                        Message 11 of 18 , Aug 8 2:06 PM
                        • 0 Attachment
                          Dodi,

                          --- digidodi <ddierick@...> wrote:
                          > Well, it's not the camera either. I made pictures
                          > last night with an
                          > MK69 Intes, full frame with the D100, and in all
                          > directions the image
                          > is tacksharp. I used the same camera and adapter.
                          > The only thing
                          > which is not the same is the Televue reducer. I have
                          > now also a Borg
                          > flattener to rule out the Televue.
                          >
                          > It puzzles me as much as it puzzles you. I will do
                          > the test with the
                          > new tube as soon as possible!
                          >
                          > Dodi
                          --------

                          I think the reducer is an important part of the
                          problem.

                          The following things come to mind.

                          1. The reducer is almost at the focal plane. So it
                          could be very sensitive to lateral displacement of
                          it's optical axis from the objective's optical axis.

                          2. The reducer is adding its own aberrations.
                          Without the reducer, the sharp field of view is
                          probably a good deal larger than your CCD chip. With
                          the reducer, the sharp field of view may be almost the
                          same size as your CCD chip.

                          If that is the case, the system could be VERY
                          SENSITIVE to the CCD chip being slightly offset
                          laterally from the optical axis WITH THE REDUCER in
                          place. But the same chip offset error could be
                          undetectible without the reducer in the system. And
                          the sensitivity could be different with different
                          reducers.

                          3. A Maksutov has different residual aberrations than
                          a refractor, and your reducer may not perform
                          identically with the two very different optical
                          systems.

                          4. The two reducers could perform noticeably
                          differently from each other.

                          So I am suggesting you be cautious about eliminating
                          certain possibilities unless you are controlling all
                          variables except the one you know you are changing.

                          I am also making suggestions from a very theoretical
                          point of view. I have no tools at hand to judge HOW
                          MUCH any of the things I mentioned above would affect
                          your image.

                          Since Markus' tests seem to rule out the
                          tube/objective part of the system, my best guess from
                          all you have said is still that your CCD chip is not
                          exactly centered in the middle of the eyepiece tube.

                          Richard

                          __________________________________
                          Do you Yahoo!?
                          Yahoo! SiteBuilder - Free, easy-to-use web site design software
                          http://sitebuilder.yahoo.com
                        • Adrian Catterall
                          I have forgotten the details of your tests, but one possibility is that the focuser is sagging a little. I have this on the TMB 80 and tested with an ST10. The
                          Message 12 of 18 , Aug 8 2:37 PM
                          • 0 Attachment
                            I have forgotten the details of your tests, but one possibility is that
                            the focuser is sagging a little. I have this on the TMB 80 and tested
                            with an ST10. The focal plane is quite a way back from the focuser.
                            Hopefully Markus can make an OTA extension to get round this problem.

                            Adrian


                            In message <bh0omu+q8jl@...>, digidodi <ddierick@...>
                            writes
                            >Well, it's not the camera either. I made pictures last night with an
                            >MK69 Intes, full frame with the D100, and in all directions the image
                            >is tacksharp. I used the same camera and adapter. The only thing
                            >which is not the same is the Televue reducer. I have now also a Borg
                            >flattener to rule out the Televue.
                            >
                            >It puzzles me as much as it puzzles you. I will do the test with the
                            >new tube as soon as possible!
                            >
                            >Dodi
                            >
                            >
                            >--- In tmboptical@yahoogroups.com, "Markus Ludes"
                            ><apm_telescopes@w...> wrote:
                            >> the tube arrived here. A laser test showed that the mechanical
                            >parts have been straight. A coolimation test of the lens showed both
                            >reflections to be 100% concentric too, the startest used up to any
                            >power was also perfect.
                            >>
                            >> As dominique wished I have send him back his tube with another
                            >which passed the test in same way.
                            >>
                            >> To be honest I have no idea whats going on here, but in my opinion
                            >it cannot be the tube and it cannot be the lens, otherwise one of
                            >both must show a fault.
                            >>
                            >> will be interested to see the new images from Dodi
                            >>
                            >> Markus
                            >>   ----- Original Message -----
                            >>   From: Richard Chalfan
                            >>   To: tmboptical@yahoogroups.com
                            >>   Sent: Friday, August 01, 2003 9:30 PM
                            >>   Subject: Re: [tmboptical] Re: Final squareness/lens test. Problem
                            >found
                            >>
                            >>
                            >>
                            >>   --- digidodi <ddierick@h...> wrote:
                            >>
                            >>   > Unless as I suspect the error is lateral in the lens
                            >>   > or cell. Then
                            >>   > you would still have good on axis performance, but
                            >>   > as all
                            >>   > photographers know, if you move the camera laterally
                            >>   > away from the
                            >>   > axis for one reason or another, you get uneven
                            >>   > aberation because you
                            >>   > are putting part of the image zone outside the
                            >>   > aberation free image
                            >>   > circle. I think this is what's happening.
                            >>   >
                            >>   Dodi,
                            >>
                            >>   If by lateral error, you mean that the optical axis of
                            >>   the lens does not go down the center of the tube (that
                            >>   is, the optical axis is offset from the tube's
                            >>   mechanical axis, but they are parallel), then yes,
                            >>   your CCD images would look like what you posted. 
                            >>
                            >>   Your pictures model my earlier suggestion too.  The
                            >>   aberrations on one side are more pronounced than those
                            >>   on the other side if the CCD is perpendicular to, but
                            >>   not centered on, the mechanical (and optical) axis of
                            >>   the scope.
                            >>
                            >>   But if the lens is perfect and the optical axis of the
                            >>   lens is perpendicular to the CCD chip, though
                            >>   laterally offset, you should be able to see that in a
                            >>   star test. 
                            >>
                            >>   The Airy disk rings will only be perfectly concentric
                            >>   ON the objective's optical axis.  With a laterally
                            >>   offset axis, you would see perfectly concentric rings
                            >>   off of the center of the field, and non-concentric
                            >>   rings when the star was in the middle of the field.
                            >>
                            >>   The reason I earlier suggested an offset chip, is
                            >>   because that condition still gives a perfect star test
                            >>   in a perfect scope.  It is the only condition I can
                            >>   think of off hand, where you get a perfect star test,
                            >>   but your CCD image is both properly focused and
                            >>   abberationally unsymmetrical.
                            >>
                            >>   If the lens is tilted (the objective axis is at an
                            >>   angle to the tube's mechanical axis and to the
                            >>   eyepiece axis) then you will see an Airy disk with
                            >>   off-axis aberrations.  And your CCD chip should have a
                            >>   band of good focus, going slightly out of focus on
                            >>   either side of the band.
                            >>
                            >>   If the lens elements are not mounted properly within
                            >>   the cell, then you will not see a "perfect" Airy disk
                            >>   even on axis.  I think it would look rather
                            >>   astigmatic.
                            >>
                            >>   So your symptoms sound slightly conflicting.  However,
                            >>   if the errors are small the "theoretical" symptoms may
                            >>   be hard to detect.  I think sending the tube back to
                            >>   Marcus is a reasonable start.  It is possible though,
                            >>   that he will find no problem with the lens or the
                            >>   tube.
                            >>
                            >>   Please let us know how this turns out.
                            >>
                            >>   Good luck!!!!
                            >>
                            >>   Richard
                            >>   >
                            >>
                            >>   __________________________________
                            >>   Do you Yahoo!?
                            >>   Yahoo! SiteBuilder - Free, easy-to-use web site design software
                            >>   http://sitebuilder.yahoo.com
                            >>
                            >>         Yahoo! Groups Sponsor
                            >>               ADVERTISEMENT
                            >>             
                            >>       
                            >>       
                            >>
                            >>   To unsubscribe from this group, send an email to:
                            >>   tmboptical-unsubscribe@egroups.com
                            >>
                            >>
                            >>
                            >>   Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                            >Service.
                            >>
                            >>
                            >>
                            >> [Non-text portions of this message have been removed]
                            >
                            >
                            >Yahoo! Groups Sponsor ADVERTISEMENT
                            >click here
                            >http://us.adserver.yahoo.com/l?M=251812.3170658.4537139.1261774/D=egroupmail/S=:HM/A=1693353/rand=460575369
                            >To unsubscribe from this group, send an email to:
                            >tmboptical-unsubscribe@egroups.com
                            >
                            >
                            >
                            >Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

                            --
                            Adrian Catterall
                            Amateur Astronomer
                            Hertfordshire UK
                            http://www.observatory.demon.co.uk/
                          • digidodi
                            Hi Adrian, I don t need any extension with the TV reducer, only one tube, the first one to reach focus with my D100 and the TMB. But read my other post for
                            Message 13 of 18 , Aug 8 2:49 PM
                            • 0 Attachment
                              Hi Adrian,

                              I don't need any extension with the TV reducer, only one tube, the
                              first one to reach focus with my D100 and the TMB.

                              But read my other post for interesting info.

                              Dodi


                              --- In tmboptical@yahoogroups.com, Adrian Catterall <Catterall@o...>
                              wrote:
                              > I have forgotten the details of your tests, but one possibility is
                              that
                              > the focuser is sagging a little. I have this on the TMB 80 and
                              tested
                              > with an ST10. The focal plane is quite a way back from the focuser.
                              > Hopefully Markus can make an OTA extension to get round this
                              problem.
                              >
                              > Adrian
                              >
                              >
                              > In message <bh0omu+q8jl@e...>, digidodi <ddierick@h...>
                              > writes
                              > >Well, it's not the camera either. I made pictures last night with
                              an
                              > >MK69 Intes, full frame with the D100, and in all directions the
                              image
                              > >is tacksharp. I used the same camera and adapter. The only thing
                              > >which is not the same is the Televue reducer. I have now also a
                              Borg
                              > >flattener to rule out the Televue.
                              > >
                              > >It puzzles me as much as it puzzles you. I will do the test with
                              the
                              > >new tube as soon as possible!
                              > >
                              > >Dodi
                              > >
                              > >
                              > >--- In tmboptical@yahoogroups.com, "Markus Ludes"
                              > ><apm_telescopes@w...> wrote:
                              > >> the tube arrived here. A laser test showed that the mechanical
                              > >parts have been straight. A coolimation test of the lens showed
                              both
                              > >reflections to be 100% concentric too, the startest used up to any
                              > >power was also perfect.
                              > >>
                              > >> As dominique wished I have send him back his tube with another
                              > >which passed the test in same way.
                              > >>
                              > >> To be honest I have no idea whats going on here, but in my
                              opinion
                              > >it cannot be the tube and it cannot be the lens, otherwise one of
                              > >both must show a fault.
                              > >>
                              > >> will be interested to see the new images from Dodi
                              > >>
                              > >> Markus
                              > >>   ----- Original Message -----
                              > >>   From: Richard Chalfan
                              > >>   To: tmboptical@yahoogroups.com
                              > >>   Sent: Friday, August 01, 2003 9:30 PM
                              > >>   Subject: Re: [tmboptical] Re: Final squareness/lens test.
                              Problem
                              > >found
                              > >>
                              > >>
                              > >>
                              > >>   --- digidodi <ddierick@h...> wrote:
                              > >>
                              > >>   > Unless as I suspect the error is lateral in the lens
                              > >>   > or cell. Then
                              > >>   > you would still have good on axis performance, but
                              > >>   > as all
                              > >>   > photographers know, if you move the camera laterally
                              > >>   > away from the
                              > >>   > axis for one reason or another, you get uneven
                              > >>   > aberation because you
                              > >>   > are putting part of the image zone outside the
                              > >>   > aberation free image
                              > >>   > circle. I think this is what's happening.
                              > >>   >
                              > >>   Dodi,
                              > >>
                              > >>   If by lateral error, you mean that the optical axis of
                              > >>   the lens does not go down the center of the tube (that
                              > >>   is, the optical axis is offset from the tube's
                              > >>   mechanical axis, but they are parallel), then yes,
                              > >>   your CCD images would look like what you posted. 
                              > >>
                              > >>   Your pictures model my earlier suggestion too.  The
                              > >>   aberrations on one side are more pronounced than those
                              > >>   on the other side if the CCD is perpendicular to, but
                              > >>   not centered on, the mechanical (and optical) axis of
                              > >>   the scope.
                              > >>
                              > >>   But if the lens is perfect and the optical axis of the
                              > >>   lens is perpendicular to the CCD chip, though
                              > >>   laterally offset, you should be able to see that in a
                              > >>   star test. 
                              > >>
                              > >>   The Airy disk rings will only be perfectly concentric
                              > >>   ON the objective's optical axis.  With a laterally
                              > >>   offset axis, you would see perfectly concentric rings
                              > >>   off of the center of the field, and non-concentric
                              > >>   rings when the star was in the middle of the field.
                              > >>
                              > >>   The reason I earlier suggested an offset chip, is
                              > >>   because that condition still gives a perfect star test
                              > >>   in a perfect scope.  It is the only condition I can
                              > >>   think of off hand, where you get a perfect star test,
                              > >>   but your CCD image is both properly focused and
                              > >>   abberationally unsymmetrical.
                              > >>
                              > >>   If the lens is tilted (the objective axis is at an
                              > >>   angle to the tube's mechanical axis and to the
                              > >>   eyepiece axis) then you will see an Airy disk with
                              > >>   off-axis aberrations.  And your CCD chip should have a
                              > >>   band of good focus, going slightly out of focus on
                              > >>   either side of the band.
                              > >>
                              > >>   If the lens elements are not mounted properly within
                              > >>   the cell, then you will not see a "perfect" Airy disk
                              > >>   even on axis.  I think it would look rather
                              > >>   astigmatic.
                              > >>
                              > >>   So your symptoms sound slightly conflicting.  However,
                              > >>   if the errors are small the "theoretical" symptoms may
                              > >>   be hard to detect.  I think sending the tube back to
                              > >>   Marcus is a reasonable start.  It is possible though,
                              > >>   that he will find no problem with the lens or the
                              > >>   tube.
                              > >>
                              > >>   Please let us know how this turns out.
                              > >>
                              > >>   Good luck!!!!
                              > >>
                              > >>   Richard
                              > >>   >
                              > >>
                              > >>   __________________________________
                              > >>   Do you Yahoo!?
                              > >>   Yahoo! SiteBuilder - Free, easy-to-use web site design software
                              > >>   http://sitebuilder.yahoo.com
                              > >>
                              > >>         Yahoo! Groups Sponsor
                              > >>               ADVERTISEMENT
                              > >>             
                              > >>       
                              > >>       
                              > >>
                              > >>   To unsubscribe from this group, send an email to:
                              > >>   tmboptical-unsubscribe@egroups.com
                              > >>
                              > >>
                              > >>
                              > >>   Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                              > >Service.
                              > >>
                              > >>
                              > >>
                              > >> [Non-text portions of this message have been removed]
                              > >
                              > >
                              > >Yahoo! Groups Sponsor ADVERTISEMENT
                              > >click here
                              > >http://us.adserver.yahoo.com/l?
                              M=251812.3170658.4537139.1261774/D=egroupmail/S=:HM/A=1693353/rand=460
                              575369
                              > >To unsubscribe from this group, send an email to:
                              > >tmboptical-unsubscribe@egroups.com
                              > >
                              > >
                              > >
                              > >Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                              Service.
                              >
                              > --
                              > Adrian Catterall
                              > Amateur Astronomer
                              > Hertfordshire UK
                              > http://www.observatory.demon.co.uk/
                            Your message has been successfully submitted and would be delivered to recipients shortly.