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Re: Barrel Distortion

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  • Tony
    Ok, I have the same camera. Tell me what objective and eyepiece you are using and I ll see if I can see the same sort of distortion. I normally use 2.5x or
    Message 1 of 14 , Nov 1, 2010
      Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.

      You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.

      Tony

      Reading UK




      --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
      >
      > HiTony,
      > The camera is a 1000D Cannon, I think for pollen just use the middle
      > of image, for larger subjects like aphids, no eye piece.
      >
      > David
      >
      > ----- Original Message -----
      > From: Tony
      > To: Microscope@yahoogroups.com
      > Sent: Sunday, October 31, 2010 10:10 AM
      > Subject: [Microscope] Re: Barrel Distortion
      >
      >
      >
      > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
      >
      > Tony
      >
      > Reading UK
      >
      > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
      > >
      > > Hi,
      > > I use manly no eye piece on the microscope, focused from computer
      > > screen. Have put an eye piece in, and am getting Barrel Distortion.
      > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
      > > Have tried different power eye pieces, some help.
      > > Thanks,
      > > David
      > >
      > > [Non-text portions of this message have been removed]
      > >
      >
      >
      >
      >
      > ------------------------------------------------------------------------------
      >
      > No virus found in this message.
      > Checked by AVG - www.avg.com
      > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
      >
      >
      > [Non-text portions of this message have been removed]
      >
    • david barriball
      Hi Tony, The objectives are x9,x20,x40. The eyepieces are x8, x15. The objectives are all focused on the grid of a counting chamber dry, it shows up quite
      Message 2 of 14 , Nov 1, 2010
        Hi Tony,
        The objectives are x9,x20,x40. The eyepieces are x8, x15.
        The objectives are all focused on the grid of a counting chamber dry, it shows
        up quite plainly.
        David

        ----- Original Message -----
        From: Tony
        To: Microscope@yahoogroups.com
        Sent: Monday, November 01, 2010 9:01 AM
        Subject: [Microscope] Re: Barrel Distortion



        Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.

        You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.

        Tony

        Reading UK

        --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
        >
        > HiTony,
        > The camera is a 1000D Cannon, I think for pollen just use the middle
        > of image, for larger subjects like aphids, no eye piece.
        >
        > David
        >
        > ----- Original Message -----
        > From: Tony
        > To: Microscope@yahoogroups.com
        > Sent: Sunday, October 31, 2010 10:10 AM
        > Subject: [Microscope] Re: Barrel Distortion
        >
        >
        >
        > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
        >
        > Tony
        >
        > Reading UK
        >
        > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
        > >
        > > Hi,
        > > I use manly no eye piece on the microscope, focused from computer
        > > screen. Have put an eye piece in, and am getting Barrel Distortion.
        > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
        > > Have tried different power eye pieces, some help.
        > > Thanks,
        > > David
        > >
        > > [Non-text portions of this message have been removed]
        > >
        >
        >
        >
        >
        > ----------------------------------------------------------
        >
        > No virus found in this message.
        > Checked by AVG - www.avg.com
        > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
        >
        >
        > [Non-text portions of this message have been removed]
        >




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

        No virus found in this message.
        Checked by AVG - www.avg.com
        Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10


        [Non-text portions of this message have been removed]
      • John
        Are those normal eyepieces or photo relay lenses David? John
        Message 3 of 14 , Nov 1, 2010
          Are those normal eyepieces or photo relay lenses David?

          John

          --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
          >
          > Hi Tony,
          > The objectives are x9,x20,x40. The eyepieces are x8, x15.
          > The objectives are all focused on the grid of a counting chamber dry, it shows
          > up quite plainly.
          > David
          >
          > ----- Original Message -----
          > From: Tony
          > To: Microscope@yahoogroups.com
          > Sent: Monday, November 01, 2010 9:01 AM
          > Subject: [Microscope] Re: Barrel Distortion
          >
          >
          >
          > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
          >
          > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
          >
          > Tony
          >
          > Reading UK
          >
          > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
          > >
          > > HiTony,
          > > The camera is a 1000D Cannon, I think for pollen just use the middle
          > > of image, for larger subjects like aphids, no eye piece.
          > >
          > > David
          > >
          > > ----- Original Message -----
          > > From: Tony
          > > To: Microscope@yahoogroups.com
          > > Sent: Sunday, October 31, 2010 10:10 AM
          > > Subject: [Microscope] Re: Barrel Distortion
          > >
          > >
          > >
          > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
          > >
          > > Tony
          > >
          > > Reading UK
          > >
          > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
          > > >
          > > > Hi,
          > > > I use manly no eye piece on the microscope, focused from computer
          > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
          > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
          > > > Have tried different power eye pieces, some help.
          > > > Thanks,
          > > > David
          > > >
          > > > [Non-text portions of this message have been removed]
          > > >
          > >
          > >
          > >
          > >
          > > ----------------------------------------------------------
          > >
          > > No virus found in this message.
          > > Checked by AVG - www.avg.com
          > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
          > >
          > >
          > > [Non-text portions of this message have been removed]
          > >
          >
          >
          >
          >
          > ------------------------------------------------------------------------------
          >
          > No virus found in this message.
          > Checked by AVG - www.avg.com
          > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
          >
          >
          > [Non-text portions of this message have been removed]
          >
        • david barriball
          Normal ones John. David ... From: John To: Microscope@yahoogroups.com Sent: Monday, November 01, 2010 7:47 PM Subject: [Microscope] Re: Barrel Distortion Are
          Message 4 of 14 , Nov 1, 2010
            Normal ones John.
            David
            ----- Original Message -----
            From: John
            To: Microscope@yahoogroups.com
            Sent: Monday, November 01, 2010 7:47 PM
            Subject: [Microscope] Re: Barrel Distortion



            Are those normal eyepieces or photo relay lenses David?

            John

            --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
            >
            > Hi Tony,
            > The objectives are x9,x20,x40. The eyepieces are x8, x15.
            > The objectives are all focused on the grid of a counting chamber dry, it shows
            > up quite plainly.
            > David
            >
            > ----- Original Message -----
            > From: Tony
            > To: Microscope@yahoogroups.com
            > Sent: Monday, November 01, 2010 9:01 AM
            > Subject: [Microscope] Re: Barrel Distortion
            >
            >
            >
            > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
            >
            > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
            >
            > Tony
            >
            > Reading UK
            >
            > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
            > >
            > > HiTony,
            > > The camera is a 1000D Cannon, I think for pollen just use the middle
            > > of image, for larger subjects like aphids, no eye piece.
            > >
            > > David
            > >
            > > ----- Original Message -----
            > > From: Tony
            > > To: Microscope@yahoogroups.com
            > > Sent: Sunday, October 31, 2010 10:10 AM
            > > Subject: [Microscope] Re: Barrel Distortion
            > >
            > >
            > >
            > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
            > >
            > > Tony
            > >
            > > Reading UK
            > >
            > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
            > > >
            > > > Hi,
            > > > I use manly no eye piece on the microscope, focused from computer
            > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
            > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
            > > > Have tried different power eye pieces, some help.
            > > > Thanks,
            > > > David
            > > >
            > > > [Non-text portions of this message have been removed]
            > > >
            > >
            > >
            > >
            > >
            > > ----------------------------------------------------------
            > >
            > > No virus found in this message.
            > > Checked by AVG - www.avg.com
            > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
            > >
            > >
            > > [Non-text portions of this message have been removed]
            > >
            >
            >
            >
            >
            > ----------------------------------------------------------
            >
            > No virus found in this message.
            > Checked by AVG - www.avg.com
            > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
            >
            >
            > [Non-text portions of this message have been removed]
            >




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

            No virus found in this message.
            Checked by AVG - www.avg.com
            Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10


            [Non-text portions of this message have been removed]
          • John
            That s likely to be your problem in 2 ways. The eye copes well with field curvature within reason so eyepieces may not fully correct for it. When an eyepiece
            Message 5 of 14 , Nov 1, 2010
              That's likely to be your problem in 2 ways. The eye copes well with field curvature within reason so eyepieces may not fully correct for it. When an eyepiece is spaced out for use in projection mode the curvature increases. If you look carefully you may also see increased fuzziness in places, it wont be dead sharp across the entire field. Even if it's a highly corrected eyepiece it's unlikely to produce a flat image when used for projection. The technique is often used on astro scopes and the same problem limits the useful amount of magnification that can be obtained. In that case some eyepieces work better than others. It might be worth asking that question on the basis of what make of objectives you use but personally I would be inclined to get a matching photo relay lens. Those are designed to give a flat distortion free image. That's the other possible problem with using normal eyepieces for projection - they will be corrected for normal viewing. Alter the position of the focal plain and all sorts of things could happen including barrel distortion, field curvature changes and a worsening of all of the other optical aberrations.

              John

              --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
              >
              > Normal ones John.
              > David
              > ----- Original Message -----
              > From: John
              > To: Microscope@yahoogroups.com
              > Sent: Monday, November 01, 2010 7:47 PM
              > Subject: [Microscope] Re: Barrel Distortion
              >
              >
              >
              > Are those normal eyepieces or photo relay lenses David?
              >
              > John
              >
              > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
              > >
              > > Hi Tony,
              > > The objectives are x9,x20,x40. The eyepieces are x8, x15.
              > > The objectives are all focused on the grid of a counting chamber dry, it shows
              > > up quite plainly.
              > > David
              > >
              > > ----- Original Message -----
              > > From: Tony
              > > To: Microscope@yahoogroups.com
              > > Sent: Monday, November 01, 2010 9:01 AM
              > > Subject: [Microscope] Re: Barrel Distortion
              > >
              > >
              > >
              > > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
              > >
              > > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
              > >
              > > Tony
              > >
              > > Reading UK
              > >
              > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
              > > >
              > > > HiTony,
              > > > The camera is a 1000D Cannon, I think for pollen just use the middle
              > > > of image, for larger subjects like aphids, no eye piece.
              > > >
              > > > David
              > > >
              > > > ----- Original Message -----
              > > > From: Tony
              > > > To: Microscope@yahoogroups.com
              > > > Sent: Sunday, October 31, 2010 10:10 AM
              > > > Subject: [Microscope] Re: Barrel Distortion
              > > >
              > > >
              > > >
              > > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
              > > >
              > > > Tony
              > > >
              > > > Reading UK
              > > >
              > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
              > > > >
              > > > > Hi,
              > > > > I use manly no eye piece on the microscope, focused from computer
              > > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
              > > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
              > > > > Have tried different power eye pieces, some help.
              > > > > Thanks,
              > > > > David
              > > > >
              > > > > [Non-text portions of this message have been removed]
              > > > >
              > > >
              > > >
              > > >
              > > >
              > > > ----------------------------------------------------------
              > > >
              > > > No virus found in this message.
              > > > Checked by AVG - www.avg.com
              > > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
              > > >
              > > >
              > > > [Non-text portions of this message have been removed]
              > > >
              > >
              > >
              > >
              > >
              > > ----------------------------------------------------------
              > >
              > > No virus found in this message.
              > > Checked by AVG - www.avg.com
              > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
              > >
              > >
              > > [Non-text portions of this message have been removed]
              > >
              >
              >
              >
              >
              > ------------------------------------------------------------------------------
              >
              > No virus found in this message.
              > Checked by AVG - www.avg.com
              > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
              >
              >
              > [Non-text portions of this message have been removed]
              >
            • david barriball
              Yes the x20 and x40 are Banner objectives, the x15 is a Lomo should be strain free!! David ... From: John To: Microscope@yahoogroups.com Sent: Monday, November
              Message 6 of 14 , Nov 1, 2010
                Yes the x20 and x40 are Banner objectives, the x15 is a Lomo should be strain
                free!!
                David


                ----- Original Message -----
                From: John
                To: Microscope@yahoogroups.com
                Sent: Monday, November 01, 2010 10:32 PM
                Subject: [Microscope] Re: Barrel Distortion



                That's likely to be your problem in 2 ways. The eye copes well with field curvature within reason so eyepieces may not fully correct for it. When an eyepiece is spaced out for use in projection mode the curvature increases. If you look carefully you may also see increased fuzziness in places, it wont be dead sharp across the entire field. Even if it's a highly corrected eyepiece it's unlikely to produce a flat image when used for projection. The technique is often used on astro scopes and the same problem limits the useful amount of magnification that can be obtained. In that case some eyepieces work better than others. It might be worth asking that question on the basis of what make of objectives you use but personally I would be inclined to get a matching photo relay lens. Those are designed to give a flat distortion free image. That's the other possible problem with using normal eyepieces for projection - they will be corrected for normal viewing. Alter the position of the focal plain and all sorts of things could happen including barrel distortion, field curvature changes and a worsening of all of the other optical aberrations.

                John

                --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
                >
                > Normal ones John.
                > David
                > ----- Original Message -----
                > From: John
                > To: Microscope@yahoogroups.com
                > Sent: Monday, November 01, 2010 7:47 PM
                > Subject: [Microscope] Re: Barrel Distortion
                >
                >
                >
                > Are those normal eyepieces or photo relay lenses David?
                >
                > John
                >
                > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                > >
                > > Hi Tony,
                > > The objectives are x9,x20,x40. The eyepieces are x8, x15.
                > > The objectives are all focused on the grid of a counting chamber dry, it shows
                > > up quite plainly.
                > > David
                > >
                > > ----- Original Message -----
                > > From: Tony
                > > To: Microscope@yahoogroups.com
                > > Sent: Monday, November 01, 2010 9:01 AM
                > > Subject: [Microscope] Re: Barrel Distortion
                > >
                > >
                > >
                > > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
                > >
                > > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
                > >
                > > Tony
                > >
                > > Reading UK
                > >
                > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                > > >
                > > > HiTony,
                > > > The camera is a 1000D Cannon, I think for pollen just use the middle
                > > > of image, for larger subjects like aphids, no eye piece.
                > > >
                > > > David
                > > >
                > > > ----- Original Message -----
                > > > From: Tony
                > > > To: Microscope@yahoogroups.com
                > > > Sent: Sunday, October 31, 2010 10:10 AM
                > > > Subject: [Microscope] Re: Barrel Distortion
                > > >
                > > >
                > > >
                > > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
                > > >
                > > > Tony
                > > >
                > > > Reading UK
                > > >
                > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                > > > >
                > > > > Hi,
                > > > > I use manly no eye piece on the microscope, focused from computer
                > > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
                > > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
                > > > > Have tried different power eye pieces, some help.
                > > > > Thanks,
                > > > > David
                > > > >
                > > > > [Non-text portions of this message have been removed]
                > > > >
                > > >
                > > >
                > > >
                > > >
                > > > ----------------------------------------------------------
                > > >
                > > > No virus found in this message.
                > > > Checked by AVG - www.avg.com
                > > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
                > > >
                > > >
                > > > [Non-text portions of this message have been removed]
                > > >
                > >
                > >
                > >
                > >
                > > ----------------------------------------------------------
                > >
                > > No virus found in this message.
                > > Checked by AVG - www.avg.com
                > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                > >
                > >
                > > [Non-text portions of this message have been removed]
                > >
                >
                >
                >
                >
                > ----------------------------------------------------------
                >
                > No virus found in this message.
                > Checked by AVG - www.avg.com
                > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                >
                >
                > [Non-text portions of this message have been removed]
                >




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

                No virus found in this message.
                Checked by AVG - www.avg.com
                Version: 10.0.1153 / Virus Database: 424/3231 - Release Date: 11/01/10


                [Non-text portions of this message have been removed]
              • Tony
                Hmm, I ve tried a selection of different eyepieces but I haven t found a combination that gives any noticable distortion. Given the format of the camera, the
                Message 7 of 14 , Nov 2, 2010
                  Hmm,
                  I've tried a selection of different eyepieces but I haven't found a combination that gives any noticable distortion. Given the format of the camera, the x8 and x15 are quite high magnifications. What was noticable when I tried the same numbers was increased chromatic abberations.
                  Is the camera on a trinocular port, with parfocality beween visual and camera views? If there is a large difference it probably means that the photo eyepiece, or the distance from the photo tube to camera is not correct. On my Olympus the distance from the top of the photo-tube to the camera lens mount is about 104mm.
                  The usual photo eyepiece mags when using the Canon are 2.5x or 3.5x. A 1.5x would be good if I could find one.

                  Brunel do quite a reasonable 2.5x photo eyepiece for about £25 as I remember.

                  Tony

                  Reading UK

                  --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
                  >
                  > Yes the x20 and x40 are Banner objectives, the x15 is a Lomo should be strain
                  > free!!
                  > David
                  >
                  >
                  > ----- Original Message -----
                  > From: John
                  > To: Microscope@yahoogroups.com
                  > Sent: Monday, November 01, 2010 10:32 PM
                  > Subject: [Microscope] Re: Barrel Distortion
                  >
                  >
                  >
                  > That's likely to be your problem in 2 ways. The eye copes well with field curvature within reason so eyepieces may not fully correct for it. When an eyepiece is spaced out for use in projection mode the curvature increases. If you look carefully you may also see increased fuzziness in places, it wont be dead sharp across the entire field. Even if it's a highly corrected eyepiece it's unlikely to produce a flat image when used for projection. The technique is often used on astro scopes and the same problem limits the useful amount of magnification that can be obtained. In that case some eyepieces work better than others. It might be worth asking that question on the basis of what make of objectives you use but personally I would be inclined to get a matching photo relay lens. Those are designed to give a flat distortion free image. That's the other possible problem with using normal eyepieces for projection - they will be corrected for normal viewing. Alter the position of the focal plain and all sorts of things could happen including barrel distortion, field curvature changes and a worsening of all of the other optical aberrations.
                  >
                  > John
                  >
                  > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                  > >
                  > > Normal ones John.
                  > > David
                  > > ----- Original Message -----
                  > > From: John
                  > > To: Microscope@yahoogroups.com
                  > > Sent: Monday, November 01, 2010 7:47 PM
                  > > Subject: [Microscope] Re: Barrel Distortion
                  > >
                  > >
                  > >
                  > > Are those normal eyepieces or photo relay lenses David?
                  > >
                  > > John
                  > >
                  > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                  > > >
                  > > > Hi Tony,
                  > > > The objectives are x9,x20,x40. The eyepieces are x8, x15.
                  > > > The objectives are all focused on the grid of a counting chamber dry, it shows
                  > > > up quite plainly.
                  > > > David
                  > > >
                  > > > ----- Original Message -----
                  > > > From: Tony
                  > > > To: Microscope@yahoogroups.com
                  > > > Sent: Monday, November 01, 2010 9:01 AM
                  > > > Subject: [Microscope] Re: Barrel Distortion
                  > > >
                  > > >
                  > > >
                  > > > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
                  > > >
                  > > > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
                  > > >
                  > > > Tony
                  > > >
                  > > > Reading UK
                  > > >
                  > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                  > > > >
                  > > > > HiTony,
                  > > > > The camera is a 1000D Cannon, I think for pollen just use the middle
                  > > > > of image, for larger subjects like aphids, no eye piece.
                  > > > >
                  > > > > David
                  > > > >
                  > > > > ----- Original Message -----
                  > > > > From: Tony
                  > > > > To: Microscope@yahoogroups.com
                  > > > > Sent: Sunday, October 31, 2010 10:10 AM
                  > > > > Subject: [Microscope] Re: Barrel Distortion
                  > > > >
                  > > > >
                  > > > >
                  > > > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
                  > > > >
                  > > > > Tony
                  > > > >
                  > > > > Reading UK
                  > > > >
                  > > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                  > > > > >
                  > > > > > Hi,
                  > > > > > I use manly no eye piece on the microscope, focused from computer
                  > > > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
                  > > > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
                  > > > > > Have tried different power eye pieces, some help.
                  > > > > > Thanks,
                  > > > > > David
                  > > > > >
                  > > > > > [Non-text portions of this message have been removed]
                  > > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > > ----------------------------------------------------------
                  > > > >
                  > > > > No virus found in this message.
                  > > > > Checked by AVG - www.avg.com
                  > > > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
                  > > > >
                  > > > >
                  > > > > [Non-text portions of this message have been removed]
                  > > > >
                  > > >
                  > > >
                  > > >
                  > > >
                  > > > ----------------------------------------------------------
                  > > >
                  > > > No virus found in this message.
                  > > > Checked by AVG - www.avg.com
                  > > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                  > > >
                  > > >
                  > > > [Non-text portions of this message have been removed]
                  > > >
                  > >
                  > >
                  > >
                  > >
                  > > ----------------------------------------------------------
                  > >
                  > > No virus found in this message.
                  > > Checked by AVG - www.avg.com
                  > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                  > >
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                  > >
                  >
                  >
                  >
                  >
                  > ------------------------------------------------------------------------------
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                  > Checked by AVG - www.avg.com
                  > Version: 10.0.1153 / Virus Database: 424/3231 - Release Date: 11/01/10
                  >
                  >
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                  >
                • John
                  Hi Tony. I think David is using ordinary eyepieces rather than photo types. This can be done by spacing the eyepiece out of the tube. I think I remember some
                  Message 8 of 14 , Nov 2, 2010
                    Hi Tony. I think David is using ordinary eyepieces rather than photo types. This can be done by spacing the eyepiece out of the tube. I think I remember some one saying they use an 8mms spacer with a 10x periplan for their dslr. Have to wonder about a 170mms scope and 160mms eyepiece mixes as it's Leitz. Anyway it's possible to find and roughly size and locate the position of the image with a loupe or magnifying glass. I'm slowly getting round to trying this but suspect I will find that a proper photo eyepiece is the best option.

                    He could try varying the spacing but that means refocusing the camera as well each time it's changed. The objective should always be focused by eye as far as I'm aware.

                    John

                    --- In Microscope@yahoogroups.com, "Tony" <tony.pattinson@...> wrote:
                    >
                    > Hmm,
                    > I've tried a selection of different eyepieces but I haven't found a combination that gives any noticable distortion. Given the format of the camera, the x8 and x15 are quite high magnifications. What was noticable when I tried the same numbers was increased chromatic abberations.
                    > Is the camera on a trinocular port, with parfocality beween visual and camera views? If there is a large difference it probably means that the photo eyepiece, or the distance from the photo tube to camera is not correct. On my Olympus the distance from the top of the photo-tube to the camera lens mount is about 104mm.
                    > The usual photo eyepiece mags when using the Canon are 2.5x or 3.5x. A 1.5x would be good if I could find one.
                    >
                    > Brunel do quite a reasonable 2.5x photo eyepiece for about �25 as I remember.
                    >
                    > Tony
                    >
                    > Reading UK
                    >
                    > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                    > >
                    > > Yes the x20 and x40 are Banner objectives, the x15 is a Lomo should be strain
                    > > free!!
                    > > David
                    > >
                    > >
                    > > ----- Original Message -----
                    > > From: John
                    > > To: Microscope@yahoogroups.com
                    > > Sent: Monday, November 01, 2010 10:32 PM
                    > > Subject: [Microscope] Re: Barrel Distortion
                    > >
                    > >
                    > >
                    > > That's likely to be your problem in 2 ways. The eye copes well with field curvature within reason so eyepieces may not fully correct for it. When an eyepiece is spaced out for use in projection mode the curvature increases. If you look carefully you may also see increased fuzziness in places, it wont be dead sharp across the entire field. Even if it's a highly corrected eyepiece it's unlikely to produce a flat image when used for projection. The technique is often used on astro scopes and the same problem limits the useful amount of magnification that can be obtained. In that case some eyepieces work better than others. It might be worth asking that question on the basis of what make of objectives you use but personally I would be inclined to get a matching photo relay lens. Those are designed to give a flat distortion free image. That's the other possible problem with using normal eyepieces for projection - they will be corrected for normal viewing. Alter the position of the focal plain and all sorts of things could happen including barrel distortion, field curvature changes and a worsening of all of the other optical aberrations.
                    > >
                    > > John
                    > >
                    > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                    > > >
                    > > > Normal ones John.
                    > > > David
                    > > > ----- Original Message -----
                    > > > From: John
                    > > > To: Microscope@yahoogroups.com
                    > > > Sent: Monday, November 01, 2010 7:47 PM
                    > > > Subject: [Microscope] Re: Barrel Distortion
                    > > >
                    > > >
                    > > >
                    > > > Are those normal eyepieces or photo relay lenses David?
                    > > >
                    > > > John
                    > > >
                    > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                    > > > >
                    > > > > Hi Tony,
                    > > > > The objectives are x9,x20,x40. The eyepieces are x8, x15.
                    > > > > The objectives are all focused on the grid of a counting chamber dry, it shows
                    > > > > up quite plainly.
                    > > > > David
                    > > > >
                    > > > > ----- Original Message -----
                    > > > > From: Tony
                    > > > > To: Microscope@yahoogroups.com
                    > > > > Sent: Monday, November 01, 2010 9:01 AM
                    > > > > Subject: [Microscope] Re: Barrel Distortion
                    > > > >
                    > > > >
                    > > > >
                    > > > > Ok, I have the same camera. Tell me what objective and eyepiece you are using and I'll see if I can see the same sort of distortion. I normally use 2.5x or 3.5x photo eyepieces and up to 60x objectives.
                    > > > >
                    > > > > You didn't say how you noticed it. I wouldn't have thought any geometric distortion would be that noticable on normal subjects. I suppose a straight edge might show it up.
                    > > > >
                    > > > > Tony
                    > > > >
                    > > > > Reading UK
                    > > > >
                    > > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                    > > > > >
                    > > > > > HiTony,
                    > > > > > The camera is a 1000D Cannon, I think for pollen just use the middle
                    > > > > > of image, for larger subjects like aphids, no eye piece.
                    > > > > >
                    > > > > > David
                    > > > > >
                    > > > > > ----- Original Message -----
                    > > > > > From: Tony
                    > > > > > To: Microscope@yahoogroups.com
                    > > > > > Sent: Sunday, October 31, 2010 10:10 AM
                    > > > > > Subject: [Microscope] Re: Barrel Distortion
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > What is the setup - camera format etc.? It sounds as though you are using a very large area of the image if the distortion is great enough to be obvious. For comparative purposes, a grid is the usual object. If high mags are what you want, then it may be diffcult to find one fine enough.
                    > > > > >
                    > > > > > Tony
                    > > > > >
                    > > > > > Reading UK
                    > > > > >
                    > > > > > --- In Microscope@yahoogroups.com, "david barriball" <focusball3@> wrote:
                    > > > > > >
                    > > > > > > Hi,
                    > > > > > > I use manly no eye piece on the microscope, focused from computer
                    > > > > > > screen. Have put an eye piece in, and am getting Barrel Distortion.
                    > > > > > > There was none before. I wanted higher magnification, and greater working distance. So would shortening the tube help?
                    > > > > > > Have tried different power eye pieces, some help.
                    > > > > > > Thanks,
                    > > > > > > David
                    > > > > > >
                    > > > > > > [Non-text portions of this message have been removed]
                    > > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > ----------------------------------------------------------
                    > > > > >
                    > > > > > No virus found in this message.
                    > > > > > Checked by AVG - www.avg.com
                    > > > > > Version: 10.0.1153 / Virus Database: 424/3228 - Release Date: 10/30/10
                    > > > > >
                    > > > > >
                    > > > > > [Non-text portions of this message have been removed]
                    > > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > > ----------------------------------------------------------
                    > > > >
                    > > > > No virus found in this message.
                    > > > > Checked by AVG - www.avg.com
                    > > > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                    > > > >
                    > > > >
                    > > > > [Non-text portions of this message have been removed]
                    > > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > > ----------------------------------------------------------
                    > > >
                    > > > No virus found in this message.
                    > > > Checked by AVG - www.avg.com
                    > > > Version: 10.0.1153 / Virus Database: 424/3230 - Release Date: 10/31/10
                    > > >
                    > > >
                    > > > [Non-text portions of this message have been removed]
                    > > >
                    > >
                    > >
                    > >
                    > >
                    > > ------------------------------------------------------------------------------
                    > >
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                    > > Checked by AVG - www.avg.com
                    > > Version: 10.0.1153 / Virus Database: 424/3231 - Release Date: 11/01/10
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                    >
                  • david barriball
                    I have measured the distance from eyepiece (x15) to camera chip about 3 or 4 cm, to stop vignetting. from the bottom of the objective (x9) to the eyepiece it
                    Message 9 of 14 , Nov 3, 2010
                      I have measured the distance from eyepiece (x15) to camera chip about 3 or 4 cm, to stop
                      vignetting.
                      from the bottom of the objective (x9) to the eyepiece it is 18cm.
                      There is no prism on the microscope straight through, no other glass.
                      David

                      -----


                      Hmm,
                      I've tried a selection of different eyepieces but I haven't found a combination that gives any noticable distortion. Given the format of the camera, the x8 and x15 are quite high magnifications. What was noticable when I tried the same numbers was increased chromatic abberations.
                      Is the camera on a trinocular port, with parfocality beween visual and camera views? If there is a large difference it probably means that the photo eyepiece, or the distance from the photo tube to camera is not correct. On my Olympus the distance from the top of the photo-tube to the camera lens mount is about 104mm.
                      The usual photo eyepiece mags when using the Canon are 2.5x or 3.5x. A 1.5x would be good if I could find one.

                      Brunel do quite a reasonable 2.5x photo eyepiece for about £25 as I remember.

                      Tony

                      Reading UK

                      - Release Date: 11/02/10


                      [Non-text portions of this message have been removed]
                    • mervhob
                      Hi David, I have just uploaded to the Files section a PDF entitled HartingOrtho . This is a description by the lens designer Harting of the reasons why lens
                      Message 10 of 14 , Nov 3, 2010
                        Hi David,

                        I have just uploaded to the 'Files' section a PDF entitled 'HartingOrtho'. This is a description by the lens designer Harting of the reasons why lens systems are non - orthoscopic and therefore show pin cushion or barrel distortion. The problem will be worse with high magnification eyepieces, due to the curvature of the elements close to the entrance pupil. As Harting explains, only symmetrical optical systems have minimal aberration - he cites the case of the pin-hole camera where both the entrance pupil and the exit pupil are in effect at the centre of the stop. Distortion is then independant of the object and image distances from the centre of the optical system, which is why pinhole cameras give fantastic depth of field. This is definitely not the case with eyepiece projection, unless it is a properly designed photo-eyepiece, and even then the field coverage will be limited. With a small area photosensor, such as that on a webcam, you will never notice it, but projection onto the large area of the D1000 sensor is a totally different situation. Just out of interest, as I use mainly small area sensor cameras, I projected the image from a x18 Zeiss photo ocular onto a large ground glass screen - and got barrel distortion. But I would never notice it on a 5x5mm CCD!

                        Cheers,

                        Merv

                        --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
                        >
                        > I have measured the distance from eyepiece (x15) to camera chip about 3 or 4 cm, to stop
                        > vignetting.
                        > from the bottom of the objective (x9) to the eyepiece it is 18cm.
                        > There is no prism on the microscope straight through, no other glass.
                        > David
                        >
                        > -----
                        >
                        >
                        > Hmm,
                        > I've tried a selection of different eyepieces but I haven't found a combination that gives any noticable distortion. Given the format of the camera, the x8 and x15 are quite high magnifications. What was noticable when I tried the same numbers was increased chromatic abberations.
                        > Is the camera on a trinocular port, with parfocality beween visual and camera views? If there is a large difference it probably means that the photo eyepiece, or the distance from the photo tube to camera is not correct. On my Olympus the distance from the top of the photo-tube to the camera lens mount is about 104mm.
                        > The usual photo eyepiece mags when using the Canon are 2.5x or 3.5x. A 1.5x would be good if I could find one.
                        >
                        > Brunel do quite a reasonable 2.5x photo eyepiece for about £25 as I remember.
                        >
                        > Tony
                        >
                        > Reading UK
                        >
                        > - Release Date: 11/02/10
                        >
                        >
                        > [Non-text portions of this message have been removed]
                        >
                      • david barriball
                        Thanks to ALL,who have helped. David ... From: mervhob To: Microscope@yahoogroups.com Sent: Wednesday, November 03, 2010 4:24 PM Subject: [Microscope] Re:
                        Message 11 of 14 , Nov 3, 2010
                          Thanks to ALL,who have helped.

                          David


                          ----- Original Message -----
                          From: mervhob
                          To: Microscope@yahoogroups.com
                          Sent: Wednesday, November 03, 2010 4:24 PM
                          Subject: [Microscope] Re: Barrel Distortion





                          Hi David,

                          I have just uploaded to the 'Files' section a PDF entitled 'HartingOrtho'. This is a description by the lens designer Harting of the reasons why lens systems are non - orthoscopic and therefore show pin cushion or barrel distortion. The problem will be worse with high magnification eyepieces, due to the curvature of the elements close to the entrance pupil. As Harting explains, only symmetrical optical systems have minimal aberration - he cites the case of the pin-hole camera where both the entrance pupil and the exit pupil are in effect at the centre of the stop. Distortion is then independant of the object and image distances from the centre of the optical system, which is why pinhole cameras give fantastic depth of field. This is definitely not the case with eyepiece projection, unless it is a properly designed photo-eyepiece, and even then the field coverage will be limited. With a small area photosensor, such as that on a webcam, you will never notice it, but projection onto the large area of the D1000 sensor is a totally different situation. Just out of interest, as I use mainly small area sensor cameras, I projected the image from a x18 Zeiss photo ocular onto a large ground glass screen - and got barrel distortion. But I would never notice it on a 5x5mm CCD!

                          Cheers,

                          Merv

                          --- In Microscope@yahoogroups.com, "david barriball" <focusball3@...> wrote:
                          >
                          > I have measured the distance from eyepiece (x15) to camera chip about 3 or 4 cm, to stop
                          > vignetting.
                          > from the bottom of the objective (x9) to the eyepiece it is 18cm.
                          > There is no prism on the microscope straight through, no other glass.
                          > David
                          >
                          > -----
                          >
                          >
                          > Hmm,
                          > I've tried a selection of different eyepieces but I haven't found a combination that gives any noticable distortion. Given the format of the camera, the x8 and x15 are quite high magnifications. What was noticable when I tried the same numbers was increased chromatic abberations.
                          > Is the camera on a trinocular port, with parfocality beween visual and camera views? If there is a large difference it probably means that the photo eyepiece, or the distance from the photo tube to camera is not correct. On my Olympus the distance from the top of the photo-tube to the camera lens mount is about 104mm.
                          > The usual photo eyepiece mags when using the Canon are 2.5x or 3.5x. A 1.5x would be good if I could find one.
                          >
                          > Brunel do quite a reasonable 2.5x photo eyepiece for about £25 as I remember.
                          >
                          > Tony
                          >
                          > Reading UK
                          >
                          > - Release Date: 11/02/10
                          >
                          >
                          > [Non-text portions of this message have been removed]
                          >




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