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Re: WTD low power Objectives...etc.

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  • Dave Jackson
    Gordon, Very interesting... However, there are a few factors you may wish to consider in your quest. First, true macro lenses for cameras are designed to
    Message 1 of 18 , Dec 1, 2002
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      Gordon,

      Very interesting...

      However, there are a few factors you may wish to consider in your
      quest.

      First, true "macro" lenses for cameras are designed to function over
      a significant range of distances, and also to fully cover the frame
      with with a sharp, well-focused image. Since a 35mm film frame has
      a longest dimension (diagonal) of about 44mm, the image formed by
      these lenses covers at least that much. (This is why the best such
      lenses cost a fortune.)

      Naturally, camera lenses are "fully-corrected" and intended for use
      without an eyepiece.

      Microscope objectives, however, are designed to achieve their best
      performance over a much smaller image. Also, to some extent, the
      objective's performance may be dependent upon using it with a proper
      "matchng" eyepiece. This is because many microscope objectives
      (especially the "better" ones) are not "fully-corrected" by themselves
      and, instead, rely on a "matching' eyepiece to provide some additional
      optical corrections. This is done to allow the objective to achieve
      the highest possible overall performance (on a microscope).

      Now, the simpler microscope objectives (low-power) are somewhat more
      flexible, tend to be relatively insensitive to specific eyepiece
      characteristics, and would probably the best choice for your work. The
      newer and more costly "Plan" types can be fairly fussy about eyepiece
      matching (and other factors) any may not be your a good choice.

      So, just stay with the older objective types, but don't be
      surprised if the image corners are a tad "softer" than the image
      center. (Also, "depth-of-focus" may be quite shallow and most
      low-power objectives will not have a "built-in iris" to fix that
      problem!)

      All this leads to an important issue that few retailers address --
      the fact that the microscope eyepiece is usually an integral part of
      the objective's design, especially with "Plan" optics.

      Not only does the eyepiece often contribute to the "field flattening"
      of the image, but most usually it also compensates for residual color
      errors in the objective's image (so-called "chromatic difference in
      magnification"), which is minimal in the center of the image and gets
      worse toward the edges. This is effect evidenced by a blue "fringe" on
      one side of an object and an orange fringe on the opposite side --
      often quite apparent when you start to look for it.

      This effect is most visible near the edges of the image and is caused
      by a mis-match between the objective and the eyepiece. Some brands
      of objectives are less prone to this problem than others, but it is
      one reason why camera couplers based on "universal" optics (one design
      for everything) must be carefully used to get the best results. If
      the objective selected is a good match, results can be excellent.

      With an eyepiece which is a proper "match" this effect may be nearly
      undetectable. But with an eyepiece with is a poor "match", it can be
      pretty bad. Thus, it is safer to use the maker's "matching" eyepiece
      for the objective if you want the best image -- unless you understand
      the eyepiece "matching" game fairly well. (Or can accept the problem
      and take other measures to minimize it.)

      Many of the camera couplers available which rely on built-in optics
      use the old "Kellner" (telescope eyepiece) design, and are basically
      "non-compensating" -- meaning they do nothing to correct any color
      errors inherent in the objective. Consequently, these will function
      best with those objectives intended to work with "non-compensating"
      eyepieces, and may not give the best results with those objectives
      which require "compensating" eyepieces. (I won't cite examples here.)

      Finally, just to add to the confusion, this color problem will be
      grestest when attempting to image the entire visual field, but will
      become less noticeable if imaging over smaller areas is attempted.
      Thus even a badly "matched" objective-eyepiece combination can give
      acceptable results if the imaging is limited to the central part of
      the total visual field (where the objective performs best anyway).

      Now, "mechanical" couplers which rely on using the microscope's
      eyepiece do not suffer from such limitations, PROVIDED the eyepiece
      you plan to use is already a good match for the objective(s) in use
      AND satisfies the camera's optical requirements (typically, a
      sufficiently high eyepoint).

      In general, the older Bausch & Lomb (B&L) and AO/Spencer objectives
      should give good results in your application. These were intened to
      be used with "non-compensating" eyepieces and should perform well
      in with couplers having built-in optics. B&L made a series of macro
      lenses (the "Micro Tessar" series) which had a microscope thread
      AND an internal iris, and were designed for macro use without an
      eyepiece, but to cover a 4"x5" film size. These might address the
      "depth-of-field" problem but at the cost of less overall sharpness.

      Anyway, I've been down this road (years ago) and these are a few of
      the things I learned along the way. Hope this helps!

      And -- Sorry if all this has been overkill...

      Dave J.


      **************************************
      --- In Microscope@y..., "Gordon Couger" <Gordon@c...> wrote:
      > I am looking to beg, borrow buy or steal a 1x, 2x. or 2.5 x
      objective for
      > exoementing with Mark Simmons'
      > http://www.marksimmons.org/closeup/adapter/adapter.htmlshort
      micorsopes tube
      > "Modular micoscope adaptor." It 47% precent shorter than the 160 mm
      tumbe
      > the lenses are mad for. It extedns teh wroking destiacne an reduces
      the
      > magifiction fo the system. My breiff exprments look very promising
      for low
      > magivications for 2 o 3 to 100 using remote eleconic flash. My breif
      > intoduction to it is far better than stareo scopes for photraphin
      coins and
      > such.
      >
      > Any one with a surplus of thes objective let me know and lets work
      out a
      > trade ro price.
      >
      > Gordon
      > Gordon Couger gcouger@c...
      >
      > I collect links on information related to light microscopes.
      > http://www.couger.com/microscope/links/gclinks.html
      > Please forward any links or information you think might be useful to
      others.
    • Wallace Kelley
      Hi Dave, I just want to welcome you to the Microscope yahoogroup. It is a real pleasure to have someone with your knowledge and background with the group. As
      Message 2 of 18 , Dec 1, 2002
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        Hi Dave,
        I just want to welcome you to the Microscope yahoogroup. It is a real
        pleasure to have someone with your knowledge and background with the group.
        As I have told others in private emails. When you write something, I sit up
        in my seat and pay attention!
        Kind regards,
        Wallace Kelley
        <>
        ----- Original Message -----
        From: Dave Jackson <davinnj@...>
        To: <Microscope@yahoogroups.com>
        Sent: Sunday, December 01, 2002 11:23 AM
        Subject: [Microscope] Re: WTD low power Objectives...etc.


        > Gordon,
        >
        > Very interesting...
        >
        > However, there are a few factors you may wish to consider in your
        > quest.
        >
        > First, true "macro" lenses for cameras are designed to function over
        > a significant range of distances, and also to fully cover the frame
        > with with a sharp, well-focused image. Since a 35mm film frame has
        > a longest dimension (diagonal) of about 44mm, the image formed by
        > these lenses covers at least that much. (This is why the best such
        > lenses cost a fortune.)
        >
        > Naturally, camera lenses are "fully-corrected" and intended for use
        > without an eyepiece.
        >
        > Microscope objectives, however, are designed to achieve their best
        > performance over a much smaller image. Also, to some extent, the
        > objective's performance may be dependent upon using it with a proper
        > "matchng" eyepiece. This is because many microscope objectives
        > (especially the "better" ones) are not "fully-corrected" by themselves
        > and, instead, rely on a "matching' eyepiece to provide some additional
        > optical corrections. This is done to allow the objective to achieve
        > the highest possible overall performance (on a microscope).
        >
        > Now, the simpler microscope objectives (low-power) are somewhat more
        > flexible, tend to be relatively insensitive to specific eyepiece
        > characteristics, and would probably the best choice for your work. The
        > newer and more costly "Plan" types can be fairly fussy about eyepiece
        > matching (and other factors) any may not be your a good choice.
        >
        > So, just stay with the older objective types, but don't be
        > surprised if the image corners are a tad "softer" than the image
        > center. (Also, "depth-of-focus" may be quite shallow and most
        > low-power objectives will not have a "built-in iris" to fix that
        > problem!)
        >
        > All this leads to an important issue that few retailers address --
        > the fact that the microscope eyepiece is usually an integral part of
        > the objective's design, especially with "Plan" optics.
        >
        > Not only does the eyepiece often contribute to the "field flattening"
        > of the image, but most usually it also compensates for residual color
        > errors in the objective's image (so-called "chromatic difference in
        > magnification"), which is minimal in the center of the image and gets
        > worse toward the edges. This is effect evidenced by a blue "fringe" on
        > one side of an object and an orange fringe on the opposite side --
        > often quite apparent when you start to look for it.
        >
        > This effect is most visible near the edges of the image and is caused
        > by a mis-match between the objective and the eyepiece. Some brands
        > of objectives are less prone to this problem than others, but it is
        > one reason why camera couplers based on "universal" optics (one design
        > for everything) must be carefully used to get the best results. If
        > the objective selected is a good match, results can be excellent.
        >
        > With an eyepiece which is a proper "match" this effect may be nearly
        > undetectable. But with an eyepiece with is a poor "match", it can be
        > pretty bad. Thus, it is safer to use the maker's "matching" eyepiece
        > for the objective if you want the best image -- unless you understand
        > the eyepiece "matching" game fairly well. (Or can accept the problem
        > and take other measures to minimize it.)
        >
        > Many of the camera couplers available which rely on built-in optics
        > use the old "Kellner" (telescope eyepiece) design, and are basically
        > "non-compensating" -- meaning they do nothing to correct any color
        > errors inherent in the objective. Consequently, these will function
        > best with those objectives intended to work with "non-compensating"
        > eyepieces, and may not give the best results with those objectives
        > which require "compensating" eyepieces. (I won't cite examples here.)
        >
        > Finally, just to add to the confusion, this color problem will be
        > grestest when attempting to image the entire visual field, but will
        > become less noticeable if imaging over smaller areas is attempted.
        > Thus even a badly "matched" objective-eyepiece combination can give
        > acceptable results if the imaging is limited to the central part of
        > the total visual field (where the objective performs best anyway).
        >
        > Now, "mechanical" couplers which rely on using the microscope's
        > eyepiece do not suffer from such limitations, PROVIDED the eyepiece
        > you plan to use is already a good match for the objective(s) in use
        > AND satisfies the camera's optical requirements (typically, a
        > sufficiently high eyepoint).
        >
        > In general, the older Bausch & Lomb (B&L) and AO/Spencer objectives
        > should give good results in your application. These were intened to
        > be used with "non-compensating" eyepieces and should perform well
        > in with couplers having built-in optics. B&L made a series of macro
        > lenses (the "Micro Tessar" series) which had a microscope thread
        > AND an internal iris, and were designed for macro use without an
        > eyepiece, but to cover a 4"x5" film size. These might address the
        > "depth-of-field" problem but at the cost of less overall sharpness.
        >
        > Anyway, I've been down this road (years ago) and these are a few of
        > the things I learned along the way. Hope this helps!
        >
        > And -- Sorry if all this has been overkill...
        >
        > Dave J.
        >
        >
        > **************************************
        > --- In Microscope@y..., "Gordon Couger" <Gordon@c...> wrote:
        > > I am looking to beg, borrow buy or steal a 1x, 2x. or 2.5 x
        > objective for
        > > exoementing with Mark Simmons'
        > > http://www.marksimmons.org/closeup/adapter/adapter.htmlshort
        > micorsopes tube
        > > "Modular micoscope adaptor." It 47% precent shorter than the 160 mm
        > tumbe
        > > the lenses are mad for. It extedns teh wroking destiacne an reduces
        > the
        > > magifiction fo the system. My breiff exprments look very promising
        > for low
        > > magivications for 2 o 3 to 100 using remote eleconic flash. My breif
        > > intoduction to it is far better than stareo scopes for photraphin
        > coins and
        > > such.
        > >
        > > Any one with a surplus of thes objective let me know and lets work
        > out a
        > > trade ro price.
        > >
        > > Gordon
        > > Gordon Couger gcouger@c...
        > >
        > > I collect links on information related to light microscopes.
        > > http://www.couger.com/microscope/links/gclinks.html
        > > Please forward any links or information you think might be useful to
        > others.
        >
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
        >
      • Frez
        Hi Gordon and Dave You guys will always give me something to do on an afternoon at home. :} I m experimenting with the objective setup that you guys are
        Message 3 of 18 , Dec 1, 2002
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          Hi Gordon and Dave

          You guys will always give me something to do on an afternoon
          at home. :}

          I'm experimenting with the objective setup that you guys are
          discussing and getting good results with a convertible Hertel &
          Reuss 5x/10x. Removing the outer lens that makes the 5x part
          into a 10x objective and placing it inverted near the MDS100 CCD,
          the setup is producing a decent image. I'm assuming this
          objective part is magnifying 2x. Oddly it seems to work best with
          a 40x objective. Samples here:

          http://groups.yahoo.com/group/frezsmicromovies/files/

          Frez
        • Gordon Couger
          Dave, Thanks for the informative post to my post that slipped by my spell checker. My interest is to be able to photograph a nearly continuous range
          Message 4 of 18 , Dec 1, 2002
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            Dave,

            Thanks for the informative post to my post that slipped by my spell checker.

            My interest is to be able to photograph a nearly continuous range
            magnifications in the feild. I know one tube length and two objectives are
            not going to cover it all. But several tube lengths or an adjustable tube
            and several objectives should cover good deal from 5x to 200x or a little
            more for a portable system spanning the range of a stereo and the low end of
            compound microscopes in the feild

            Before build one I got the short tube from Mark because it was easy to see
            how it worked. I am going to build one from the nose piece of a reflected
            light microscope that has beam splitter that is easy to remove and build a
            light source that has a built in electronic flash to solve the problems of
            rigidity. The light source will be removable to use for oblique and
            eventually transmitted lighting.

            I am building it out of this:
            http://www.couger.com/microscope/pix/BLreflected%20_light.jpg

            Gordon

            :
            : Very interesting...
            :
            : However, there are a few factors you may wish to consider in your
            : quest.
            :
            : First, true "macro" lenses for cameras are designed to function over
            : a significant range of distances, and also to fully cover the frame
            : with with a sharp, well-focused image. Since a 35mm film frame has
            : a longest dimension (diagonal) of about 44mm, the image formed by
            : these lenses covers at least that much. (This is why the best such
            : lenses cost a fortune.)
            :
            : Naturally, camera lenses are "fully-corrected" and intended for use
            : without an eyepiece.
            :
            : Microscope objectives, however, are designed to achieve their best
            : performance over a much smaller image. Also, to some extent, the
            : objective's performance may be dependent upon using it with a proper
            : "matchng" eyepiece. This is because many microscope objectives
            : (especially the "better" ones) are not "fully-corrected" by themselves
            : and, instead, rely on a "matching' eyepiece to provide some additional
            : optical corrections. This is done to allow the objective to achieve
            : the highest possible overall performance (on a microscope).
            :
            : Now, the simpler microscope objectives (low-power) are somewhat more
            : flexible, tend to be relatively insensitive to specific eyepiece
            : characteristics, and would probably the best choice for your work. The
            : newer and more costly "Plan" types can be fairly fussy about eyepiece
            : matching (and other factors) any may not be your a good choice.
            :
            : So, just stay with the older objective types, but don't be
            : surprised if the image corners are a tad "softer" than the image
            : center. (Also, "depth-of-focus" may be quite shallow and most
            : low-power objectives will not have a "built-in iris" to fix that
            : problem!)
            :
            : All this leads to an important issue that few retailers address --
            : the fact that the microscope eyepiece is usually an integral part of
            : the objective's design, especially with "Plan" optics.
            :
            : Not only does the eyepiece often contribute to the "field flattening"
            : of the image, but most usually it also compensates for residual color
            : errors in the objective's image (so-called "chromatic difference in
            : magnification"), which is minimal in the center of the image and gets
            : worse toward the edges. This is effect evidenced by a blue "fringe" on
            : one side of an object and an orange fringe on the opposite side --
            : often quite apparent when you start to look for it.
            :
            : This effect is most visible near the edges of the image and is caused
            : by a mis-match between the objective and the eyepiece. Some brands
            : of objectives are less prone to this problem than others, but it is
            : one reason why camera couplers based on "universal" optics (one design
            : for everything) must be carefully used to get the best results. If
            : the objective selected is a good match, results can be excellent.
            :
            : With an eyepiece which is a proper "match" this effect may be nearly
            : undetectable. But with an eyepiece with is a poor "match", it can be
            : pretty bad. Thus, it is safer to use the maker's "matching" eyepiece
            : for the objective if you want the best image -- unless you understand
            : the eyepiece "matching" game fairly well. (Or can accept the problem
            : and take other measures to minimize it.)
            :
            : Many of the camera couplers available which rely on built-in optics
            : use the old "Kellner" (telescope eyepiece) design, and are basically
            : "non-compensating" -- meaning they do nothing to correct any color
            : errors inherent in the objective. Consequently, these will function
            : best with those objectives intended to work with "non-compensating"
            : eyepieces, and may not give the best results with those objectives
            : which require "compensating" eyepieces. (I won't cite examples here.)
            :
            : Finally, just to add to the confusion, this color problem will be
            : grestest when attempting to image the entire visual field, but will
            : become less noticeable if imaging over smaller areas is attempted.
            : Thus even a badly "matched" objective-eyepiece combination can give
            : acceptable results if the imaging is limited to the central part of
            : the total visual field (where the objective performs best anyway).
            :
            : Now, "mechanical" couplers which rely on using the microscope's
            : eyepiece do not suffer from such limitations, PROVIDED the eyepiece
            : you plan to use is already a good match for the objective(s) in use
            : AND satisfies the camera's optical requirements (typically, a
            : sufficiently high eyepoint).
            :
            : In general, the older Bausch & Lomb (B&L) and AO/Spencer objectives
            : should give good results in your application. These were intened to
            : be used with "non-compensating" eyepieces and should perform well
            : in with couplers having built-in optics. B&L made a series of macro
            : lenses (the "Micro Tessar" series) which had a microscope thread
            : AND an internal iris, and were designed for macro use without an
            : eyepiece, but to cover a 4"x5" film size. These might address the
            : "depth-of-field" problem but at the cost of less overall sharpness.
            :
            : Anyway, I've been down this road (years ago) and these are a few of
            : the things I learned along the way. Hope this helps!
            :
            : And -- Sorry if all this has been overkill...
            :
            : Dave J.
            :
            :
            : **************************************
            : --- In Microscope@y..., "Gordon Couger" <Gordon@c...> wrote:
            : > I am looking to beg, borrow buy or steal a 1x, 2x. or 2.5 x
            : objective for
            : > exoementing with Mark Simmons'
            : > http://www.marksimmons.org/closeup/adapter/adapter.htmlshort
            : micorsopes tube
            : > "Modular micoscope adaptor." It 47% precent shorter than the 160 mm
            : tumbe
            : > the lenses are mad for. It extedns teh wroking destiacne an reduces
            : the
            : > magifiction fo the system. My breiff exprments look very promising
            : for low
            : > magivications for 2 o 3 to 100 using remote eleconic flash. My breif
            : > intoduction to it is far better than stareo scopes for photraphin
            : coins and
            : > such.
            : >
            : > Any one with a surplus of thes objective let me know and lets work
            : out a
            : > trade ro price.
            : >
            : > Gordon
            : > Gordon Couger gcouger@c...
            : >
            : > I collect links on information related to light microscopes.
            : > http://www.couger.com/microscope/links/gclinks.html
            : > Please forward any links or information you think might be useful to
            : others.
            :
            :
            :
            :
            : Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            :
            :
          • Gordon Couger
            I haven t thought about an inverted microscope objective. I believe that is what Dancer did to make his microphotographs. He put an objective where the
            Message 5 of 18 , Dec 1, 2002
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              I haven't thought about an inverted microscope objective. I believe that is
              what Dancer did to make his microphotographs. He put an objective where the
              condenser normally is and used a microscope to focus the image of a
              illuminated negative on a slide of albumen sensitized with silver salts to
              make a positive. When he made the first microfilm.

              You are replacing the sensitized slide with your camera.

              You have come up with something that will eat up some of my time. If it
              doesn't have distortion problems that may solve some problems with the small
              size of the CCD and short working distance for macro work with video
              cameras. From your pictures look like it doesn't distortion problems. If
              that holds up when the objective is moved away from the CCD surface in will
              be handy for macro work. Working the angles out in my head I think it might
              be very useful for some things. Your pictures sure look good.

              Exactly what is your set up? You are taking a picture of a picture aren't
              you? If your not I sure want to know how you are illuminating those diatoms
              and getting that kind of contrast and white background?

              Gordon
              ----- Original Message -----
              From: "Frez" <dtetreault61@...>
              To: <Microscope@yahoogroups.com>
              Sent: Sunday, December 01, 2002 4:23 PM
              Subject: Re: [Microscope] WTD low power Objectives...etc.


              : Hi Gordon and Dave
              :
              : You guys will always give me something to do on an afternoon
              : at home. :}
              :
              : I'm experimenting with the objective setup that you guys are
              : discussing and getting good results with a convertible Hertel &
              : Reuss 5x/10x. Removing the outer lens that makes the 5x part
              : into a 10x objective and placing it inverted near the MDS100 CCD,
              : the setup is producing a decent image. I'm assuming this
              : objective part is magnifying 2x. Oddly it seems to work best with
              : a 40x objective. Samples here:
              :
              : http://groups.yahoo.com/group/frezsmicromovies/files/
              :
              : Frez
              :
              :
              :
              :
              :
              : Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              :
              :
            • Frez
              ... diatoms ... Hi Gordon Those are done with the Apophot. The MDS100 is at the trinoc port. The H&R objective part is taking the place of a relay lens and is
              Message 6 of 18 , Dec 1, 2002
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                >
                > Exactly what is your set up? You are taking a picture of a picture aren't
                > you? If your not I sure want to know how you are illuminating those
                diatoms
                > and getting that kind of contrast and white background?
                >
                > Gordon

                Hi Gordon

                Those are done with the Apophot. The MDS100 is at the trinoc port.
                The H&R objective part is taking the place of a relay lens and is in the
                butchered Kodak clamping system that came with the camera. It's
                clamped as close to the CCD as possible without vignetting. The
                magnifying factor is still too high and it's definately the wrong tool for
                the job. It was a fun way to kill the afternoon though. A lot of the pics
                were taken in oblique lighting. The Nikon condenser has an aperture
                offset adjustment that makes it easy. The lamp is a 30w tungsten.
                The oblique lighting causes a good deal of secondary color. Coupled
                with the refractive nature of the cleaned diatoms things looked pretty
                kaleidoscopic hence the B&W photos.

                Levels adjustments, background smoothing and unsharping masking are
                done in Photoshop. Sometimes I remembered to clone out that stupid
                speck of dirt to the right of center that was driving me nuts. :)

                Thanks
                Frez
              • Gordon Couger
                I am curious how much aberration it takes to show up on a Nikon CoolPix? I have done some things that I think should be causing problems that aren t causing
                Message 7 of 18 , Dec 1, 2002
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                  I am curious how much aberration it takes to show up on a Nikon CoolPix? I
                  have done some things that I think should be causing problems that aren't
                  causing any I can see. I know that what I see on the monitor is not what I
                  get in the picture due to image processing. Sometimes the results are better
                  sometimes not as good. The image processing seems to get rid of small points
                  of reflection very well. It also seems to mute some high contrast images
                  more than the usual contrast loss in digital. Of course I can get the most
                  of contrast back with some addition of artifacts from the process.

                  The resolving power of 4.2 megapixal camera is not very good compared to
                  film. It is just barley good enough for publication in most venues. I think
                  trying to make an image larger than 5x7 would be pretty iffy for anything
                  but a newspaper. I guess I need to try one of the gadgets at the photo
                  stores that make a print from a digital file an find out.

                  I am not trying to cover a wide range of distace but a wide range of
                  magnification with a reasonalbe working distance. Not with one lens but use
                  serveral. I know not to use optices that rely on he eyepiece for part of the
                  correction. Even in the case of the normal objectives I expect I may find I
                  need a funnel stop to reduce the appature of the lens so I am only using the
                  center portion of the lens just as you stop down a camera lens to get the
                  best resoluting out of it if I start using them much beyond what they are
                  designed for. Changing the tube length changes the magnification and working
                  distance of the objective. It will be intersting to see how far it goes
                  before things start to break down.

                  Gordon
                  : Very interesting...
                  :
                  : However, there are a few factors you may wish to consider in your
                  : quest.
                  :
                  : First, true "macro" lenses for cameras are designed to function over
                  : a significant range of distances, and also to fully cover the frame
                  : with with a sharp, well-focused image. Since a 35mm film frame has
                  : a longest dimension (diagonal) of about 44mm, the image formed by
                  : these lenses covers at least that much. (This is why the best such
                  : lenses cost a fortune.)
                  :
                  : Naturally, camera lenses are "fully-corrected" and intended for use
                  : without an eyepiece.
                  :
                  : Microscope objectives, however, are designed to achieve their best
                  : performance over a much smaller image. Also, to some extent, the
                  : objective's performance may be dependent upon using it with a proper
                  : "matchng" eyepiece. This is because many microscope objectives
                  : (especially the "better" ones) are not "fully-corrected" by themselves
                  : and, instead, rely on a "matching' eyepiece to provide some additional
                  : optical corrections. This is done to allow the objective to achieve
                  : the highest possible overall performance (on a microscope).
                  :
                  : Now, the simpler microscope objectives (low-power) are somewhat more
                  : flexible, tend to be relatively insensitive to specific eyepiece
                  : characteristics, and would probably the best choice for your work. The
                  : newer and more costly "Plan" types can be fairly fussy about eyepiece
                  : matching (and other factors) any may not be your a good choice.
                  :
                  : So, just stay with the older objective types, but don't be
                  : surprised if the image corners are a tad "softer" than the image
                  : center. (Also, "depth-of-focus" may be quite shallow and most
                  : low-power objectives will not have a "built-in iris" to fix that
                  : problem!)
                  :
                  : All this leads to an important issue that few retailers address --
                  : the fact that the microscope eyepiece is usually an integral part of
                  : the objective's design, especially with "Plan" optics.
                  :
                  : Not only does the eyepiece often contribute to the "field flattening"
                  : of the image, but most usually it also compensates for residual color
                  : errors in the objective's image (so-called "chromatic difference in
                  : magnification"), which is minimal in the center of the image and gets
                  : worse toward the edges. This is effect evidenced by a blue "fringe" on
                  : one side of an object and an orange fringe on the opposite side --
                  : often quite apparent when you start to look for it.
                  :
                  : This effect is most visible near the edges of the image and is caused
                  : by a mis-match between the objective and the eyepiece. Some brands
                  : of objectives are less prone to this problem than others, but it is
                  : one reason why camera couplers based on "universal" optics (one design
                  : for everything) must be carefully used to get the best results. If
                  : the objective selected is a good match, results can be excellent.
                  :
                  : With an eyepiece which is a proper "match" this effect may be nearly
                  : undetectable. But with an eyepiece with is a poor "match", it can be
                  : pretty bad. Thus, it is safer to use the maker's "matching" eyepiece
                  : for the objective if you want the best image -- unless you understand
                  : the eyepiece "matching" game fairly well. (Or can accept the problem
                  : and take other measures to minimize it.)
                  :
                  : Many of the camera couplers available which rely on built-in optics
                  : use the old "Kellner" (telescope eyepiece) design, and are basically
                  : "non-compensating" -- meaning they do nothing to correct any color
                  : errors inherent in the objective. Consequently, these will function
                  : best with those objectives intended to work with "non-compensating"
                  : eyepieces, and may not give the best results with those objectives
                  : which require "compensating" eyepieces. (I won't cite examples here.)
                  :
                  : Finally, just to add to the confusion, this color problem will be
                  : grestest when attempting to image the entire visual field, but will
                  : become less noticeable if imaging over smaller areas is attempted.
                  : Thus even a badly "matched" objective-eyepiece combination can give
                  : acceptable results if the imaging is limited to the central part of
                  : the total visual field (where the objective performs best anyway).
                  :
                  : Now, "mechanical" couplers which rely on using the microscope's
                  : eyepiece do not suffer from such limitations, PROVIDED the eyepiece
                  : you plan to use is already a good match for the objective(s) in use
                  : AND satisfies the camera's optical requirements (typically, a
                  : sufficiently high eyepoint).
                  :
                  : In general, the older Bausch & Lomb (B&L) and AO/Spencer objectives
                  : should give good results in your application. These were intened to
                  : be used with "non-compensating" eyepieces and should perform well
                  : in with couplers having built-in optics. B&L made a series of macro
                  : lenses (the "Micro Tessar" series) which had a microscope thread
                  : AND an internal iris, and were designed for macro use without an
                  : eyepiece, but to cover a 4"x5" film size. These might address the
                  : "depth-of-field" problem but at the cost of less overall sharpness.
                  :
                  : Anyway, I've been down this road (years ago) and these are a few of
                  : the things I learned along the way. Hope this helps!
                  :
                  : And -- Sorry if all this has been overkill...
                  :
                  : Dave J.
                  :
                  :
                  : **************************************
                  : --- In Microscope@y..., "Gordon Couger" <Gordon@c...> wrote:
                  : > I am looking to beg, borrow buy or steal a 1x, 2x. or 2.5 x
                  : objective for
                  : > exoementing with Mark Simmons'
                  : > http://www.marksimmons.org/closeup/adapter/adapter.htmlshort
                  : micorsopes tube
                  : > "Modular micoscope adaptor." It 47% precent shorter than the 160 mm
                  : tumbe
                  : > the lenses are mad for. It extedns teh wroking destiacne an reduces
                  : the
                  : > magifiction fo the system. My breiff exprments look very promising
                  : for low
                  : > magivications for 2 o 3 to 100 using remote eleconic flash. My breif
                  : > intoduction to it is far better than stareo scopes for photraphin
                  : coins and
                  : > such.
                  : >
                  : > Any one with a surplus of thes objective let me know and lets work
                  : out a
                  : > trade ro price.
                  : >
                  : > Gordon
                  : > Gordon Couger gcouger@c...
                  : >
                  : > I collect links on information related to light microscopes.
                  : > http://www.couger.com/microscope/links/gclinks.html
                  : > Please forward any links or information you think might be useful to
                  : others.
                  :
                  :
                  :
                  :
                  : Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                  :
                  :
                • Gordon Couger
                  It is getting real good pictures of diatoms for a MDS100. Try using it as a stand alone lens there should be a point on some of them focus on a on a distant
                  Message 8 of 18 , Dec 1, 2002
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                    It is getting real good pictures of diatoms for a MDS100.

                    Try using it as a stand alone lens there should be a point on some of them
                    focus on a on a distant object depending on the distance from the CCD.

                    See how dancer made his slides.
                    http://www.microscopy-uk.org.uk/mag/articles/winmicph.html

                    Gordon
                    ----- Original Message -----
                    From: "Frez" <dtetreault61@...>
                    To: <Microscope@yahoogroups.com>
                    Sent: Sunday, December 01, 2002 11:41 PM
                    Subject: Re: [Microscope] WTD low power Objectives...etc.


                    :
                    : >
                    : > Exactly what is your set up? You are taking a picture of a picture
                    aren't
                    : > you? If your not I sure want to know how you are illuminating those
                    : diatoms
                    : > and getting that kind of contrast and white background?
                    : >
                    : > Gordon
                    :
                    : Hi Gordon
                    :
                    : Those are done with the Apophot. The MDS100 is at the trinoc port.
                    : The H&R objective part is taking the place of a relay lens and is in the
                    : butchered Kodak clamping system that came with the camera. It's
                    : clamped as close to the CCD as possible without vignetting. The
                    : magnifying factor is still too high and it's definately the wrong tool for
                    : the job. It was a fun way to kill the afternoon though. A lot of the
                    pics
                    : were taken in oblique lighting. The Nikon condenser has an aperture
                    : offset adjustment that makes it easy. The lamp is a 30w tungsten.
                    : The oblique lighting causes a good deal of secondary color. Coupled
                    : with the refractive nature of the cleaned diatoms things looked pretty
                    : kaleidoscopic hence the B&W photos.
                    :
                    : Levels adjustments, background smoothing and unsharping masking are
                    : done in Photoshop. Sometimes I remembered to clone out that stupid
                    : speck of dirt to the right of center that was driving me nuts. :)
                    :
                    : Thanks
                    : Frez
                    :
                    :
                    :
                    :
                    :
                    :
                    :
                    :
                    : Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                    :
                    :
                  • v45bob
                    Gordon, Low power ie low na objectives are very tolerant of tube length changes. Change in the tube length is strickly dependant on the na. For dry objectives
                    Message 9 of 18 , Dec 2, 2002
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                      Gordon,

                      Low power ie low na objectives are very tolerant of tube length
                      changes.

                      Change in the tube length is strickly dependant on the na. For dry
                      objectives the tolerance ranges from of 1mm for a na of .9 to 1000mm
                      for a na of approx .18. The range for immersion objectives is 1 mm
                      for a na of 1.55 to 1000mm for a na of .55. This info is from a book
                      on photomicrography.

                      With a low power objective you have a lot of room to play with, have
                      fun.

                      Bob
                    • Gordon Couger
                      Thanks Bob, So funnel stops and a bigger electronic flash will probably moderately extend the tube length that can be used. But since I am only interested in
                      Message 10 of 18 , Dec 2, 2002
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                        Thanks Bob,

                        So funnel stops and a bigger electronic flash will probably moderately
                        extend the tube length that can be used. But since I am only interested in
                        low magnifications and the objectives will have low n.a. I should be all
                        right. Once I get into high magnification the area is pretty well covered
                        with objectives.

                        I would hate to have to pay for a objective and condenser set with a n.a. of
                        1.55 if it is possible to make one. I wonder how big it would be? I have a
                        300 mm camera lens with a n.a. of 1 that must weigh 50 pounds and it is not
                        color corrected. It is on a 9.5 inch aerial camera. Some day I mean to make
                        a telescope of it. It should make a great moon scope.

                        Gordon
                        :
                        : Low power ie low na objectives are very tolerant of tube length
                        : changes.
                        :
                        : Change in the tube length is strickly dependant on the na. For dry
                        : objectives the tolerance ranges from of 1mm for a na of .9 to 1000mm
                        : for a na of approx .18. The range for immersion objectives is 1 mm
                        : for a na of 1.55 to 1000mm for a na of .55. This info is from a book
                        : on photomicrography.
                        :
                        : With a low power objective you have a lot of room to play with, have
                        : fun.
                        :
                        : Bob
                        :
                        :
                        :
                        :
                        :
                        : Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                        :
                        :
                      • Ron
                        Okay Gordon, that does it. I now declare a moratorium on all fun and exciting things done by the members of this group. No more stereo stuff, no more fancy
                        Message 11 of 18 , Dec 2, 2002
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                          Okay Gordon, that does it. I now declare a moratorium on all fun and
                          exciting things done by the members of this group. No more stereo
                          stuff, no more fancy pictures and certainly no making moon scopes
                          until I get caught up and get to participate. Everyone must sit on
                          their hands or read boring things like trig and things to do with
                          infinity.

                          Sorry, but that's just the way it has to be.

                          --- In Microscope@y..., "Gordon Couger" <Gordon@c...> wrote:
                          > Thanks Bob,
                          >
                          > So funnel stops and a bigger electronic flash will probably
                          moderately
                          > extend the tube length that can be used. But since I am only
                          interested in
                          > low magnifications and the objectives will have low n.a. I should
                          be all
                          > right. Once I get into high magnification the area is pretty well
                          covered
                          > with objectives.
                          >
                          > I would hate to have to pay for a objective and condenser set with
                          a n.a. of
                          > 1.55 if it is possible to make one. I wonder how big it would be? I
                          have a
                          > 300 mm camera lens with a n.a. of 1 that must weigh 50 pounds and
                          it is not
                          > color corrected. It is on a 9.5 inch aerial camera. Some day I mean
                          to make
                          > a telescope of it. It should make a great moon scope.
                          >
                          > Gordon
                          > :
                          > : Low power ie low na objectives are very tolerant of tube length
                          > : changes.
                          > :
                          > : Change in the tube length is strickly dependant on the na. For
                          dry
                          > : objectives the tolerance ranges from of 1mm for a na of .9 to
                          1000mm
                          > : for a na of approx .18. The range for immersion objectives is 1
                          mm
                          > : for a na of 1.55 to 1000mm for a na of .55. This info is from a
                          book
                          > : on photomicrography.
                          > :
                          > : With a low power objective you have a lot of room to play with,
                          have
                          > : fun.
                          > :
                          > : Bob
                          > :
                          > :
                          > :
                          > :
                          > :
                          > : Your use of Yahoo! Groups is subject to
                          http://docs.yahoo.com/info/terms/
                          > :
                          > :
                        • Dave Jackson
                          Bob/Gordon, One needs to be careful not to read too much into charts in books without understanding exactly what it is they are trying to depict as such things
                          Message 12 of 18 , Dec 2, 2002
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                            Bob/Gordon,

                            One needs to be careful not to read too much into charts in books
                            without understanding exactly what it is they are trying to depict
                            as such things almost always apply to only a very specific set of
                            conditions.

                            Admittedly, the text accompanying that chart in Loveland's book is
                            a bit vague, however, it seems safe to assume that what's shown is
                            meant to depict only the objective's "on-axis" performance relative
                            to the Airy disc (or, to Loveland's favorite, the "Star Test").

                            While this is acceptable support for the argument he is making at
                            that point in the chapter, there are a number of important factors
                            which are not reflected at all in that chart, and thus can lead to
                            some confusion over the point he is trying to make -- and trouble,
                            perhaps, if one accepts that chart simply at face value.

                            The basic problem is that Loveland omits all off-axis considerations
                            in order to make his point as simply as possible. Unfortunately, in
                            the real world "off axis" is where most of the image actually is!

                            Most people won't care how "good" the center (on-axis part) of an
                            image is if the rest of it (off-axis) is a mess... (except maybe
                            a few theorists...?).

                            There are some very genuine "real world" limitations to just how much
                            tube length variation can be useful, even at low power/low-NA.

                            For example:

                            (a) As the tube length is made shorter the point can be reached
                            where the objective's image becomes too small to even fill the
                            eyepiece. (Image "vignetting" sets in.) At first, just the image
                            corners start to darken. But as tube length is reduced further the
                            image just grows smaller and becomed surrounded by black.) Also,
                            many objectives incorporate built-in "glare stops" which can make
                            this problem even worse.

                            (b) With a shortened tube length, more and more of the image becomes
                            "off axis" (as the eyepiece "sees" more and more of the poorly-
                            corrected parts of the image) and overall image quality diminishes
                            because of this. In other words, the outer areas of the image appear
                            to get worse as the original image area gets smaller and smaller.
                            How quickly this becomes objectionable depends a lot on the off-axis
                            performance of the objective in use. Reducing the lens aperture (NA)
                            can help with this problem, but at the cost of some resolution.

                            (c) As the tube length is made longer the lens must be moved closer
                            to the object to remain in focus. There are physical limits to just
                            how close this can be, but usually the illumination (if reflected)
                            is the first limitation here. (And, with some highly-corrected
                            objective designs focus becomes impossible if the tube length is
                            too long, as the object focus can actually move inside the lens!)

                            (d) With longer tube length there is more magnification, but the
                            point may quickly be reached where the "empty magnification" limit
                            is exceeded -- especially with low-NA objectives. Thus the image just
                            becomes larger and more blurred with no increase in detail, making
                            any further increases in tube length pointless. Unless you are using
                            a low-resolution camera, you are usually better off with a lot less
                            magnification (tube length) and then just "cropping" the image to
                            extract what you want -- at least that way something will be sharp.

                            (e) In either direction, departure from the design tube length will
                            result in diminished off-axis optical performance and increased
                            aberrations. The specifics depend on the lens design, its NA, and
                            how much the tube length deviates from nominal. ("On-axis" may remain
                            perfectly acceptable, but that is not where most of the image is.)

                            So, despite what that chart first seems to show, there are some
                            "real world" limits to the usable tube length range for a given
                            objective, even for "simple" objectives. (And, for "highly corrected"
                            objectives like "Plan" types, there can be even more problems...)

                            As with most things, there's only so much you can get for free
                            (and only so far you can stretch/shrink things...)

                            This is not to meant dissuade you from what you are attempting --
                            just to point out a few things you might wish to consider.

                            Some "quick-and-easy" testing should allow you to demonstrate the
                            above points for yourself, using whatever optics you already have.

                            This should give you a good sense of just what the limitations may
                            be in your application. And, if your range of tube lengths is limited
                            enough, you might not encounter any significant problems at all!

                            Finally (as if this would never end..!), with some setups it may be
                            easier just to rely on the "digital zoom" feature of the camera
                            rather than constantly have to fiddle with the tube length.

                            Good luck!! (And have fun...)

                            Dave J.


                            *******************************************************
                            --- In Microscope@y..., "v45bob" <rosunley@s...> wrote:
                            > Gordon,
                            >
                            > Low power ie low na objectives are very tolerant of tube length
                            > changes.
                            >
                            > Change in the tube length is strickly dependant on the na. For dry
                            > objectives the tolerance ranges from of 1mm for a na of .9 to 1000mm
                            > for a na of approx .18. The range for immersion objectives is 1 mm
                            > for a na of 1.55 to 1000mm for a na of .55. This info is from a book
                            > on photomicrography.
                            >
                            > With a low power objective you have a lot of room to play with, have
                            > fun.
                            >
                            > Bob
                          • Dave Jackson
                            Ron, Perhaps the stuff most nearly extending to infinity in this Group are some of my replies! Sorry to get so wordy guys -- I ll try to restrain myself...
                            Message 13 of 18 , Dec 2, 2002
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                              Ron,

                              Perhaps the stuff most nearly extending to "infinity" in this
                              Group are some of my replies!

                              Sorry to get so wordy guys -- I'll try to restrain myself...
                              (and they're probably "boring" as well -- another fix long overdue?)

                              Dave J.


                              **********************************************

                              --- In Microscope@y..., "Ron" <sdss_1044_0125@y...> wrote:
                              > Okay Gordon, that does it. I now declare a moratorium on all fun
                              and
                              > exciting things done by the members of this group. No more stereo
                              > stuff, no more fancy pictures and certainly no making moon scopes
                              > until I get caught up and get to participate. Everyone must sit on
                              > their hands or read boring things like trig and things to do with
                              > infinity.
                              >
                              > Sorry, but that's just the way it has to be.
                              >
                            • Julian Smith III
                              They re hardly boring Dave--at least from my end of the table, they re very welcome and informative JSIII ... -- Julian Smith III Rock Hill, SC
                              Message 14 of 18 , Dec 2, 2002
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                                They're hardly boring Dave--at least from my end of the table,
                                they're very welcome and informative
                                JSIII

                                >Ron,
                                >
                                >Perhaps the stuff most nearly extending to "infinity" in this
                                >Group are some of my replies!
                                >
                                >Sorry to get so wordy guys -- I'll try to restrain myself...
                                >(and they're probably "boring" as well -- another fix long overdue?)
                                >
                                >Dave J.
                                >
                                >
                                >**********************************************
                                >
                                >--- In Microscope@y..., "Ron" <sdss_1044_0125@y...> wrote:
                                >> Okay Gordon, that does it. I now declare a moratorium on all fun
                                >and
                                >> exciting things done by the members of this group. No more stereo
                                >> stuff, no more fancy pictures and certainly no making moon scopes
                                >> until I get caught up and get to participate. Everyone must sit on
                                >> their hands or read boring things like trig and things to do with
                                >> infinity.
                                >>
                                >> Sorry, but that's just the way it has to be.
                                >>
                                >
                                >
                                >
                                >
                                >
                                >
                                >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


                                --
                                Julian Smith III
                                Rock Hill, SC
                              • Frez
                                Same here. Even the most obscure piece of knowledge will at some time be useful. Keep it up. Frez
                                Message 15 of 18 , Dec 2, 2002
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                                  Same here. Even the most obscure piece of knowledge
                                  will at some time be useful. Keep it up.

                                  Frez


                                  > They're hardly boring Dave--at least from my end of the table,
                                  > they're very welcome and informative
                                  > JSIII
                                  >
                                  > >Ron,
                                  > >
                                  > >Perhaps the stuff most nearly extending to "infinity" in this
                                  > >Group are some of my replies!
                                  > >
                                  > >Sorry to get so wordy guys -- I'll try to restrain myself...
                                  > >(and they're probably "boring" as well -- another fix long overdue?)
                                  > >
                                  > >Dave J.
                                  > >
                                  > >
                                  > >**********************************************
                                  > >
                                  > >--- In Microscope@y..., "Ron" <sdss_1044_0125@y...> wrote:
                                  > >> Okay Gordon, that does it. I now declare a moratorium on all fun
                                  > >and
                                  > >> exciting things done by the members of this group. No more stereo
                                  > >> stuff, no more fancy pictures and certainly no making moon scopes
                                  > >> until I get caught up and get to participate. Everyone must sit on
                                  > >> their hands or read boring things like trig and things to do with
                                  > >> infinity.
                                  > >>
                                  > >> Sorry, but that's just the way it has to be.
                                  > >>
                                  > >
                                  > >
                                  > >
                                  > >
                                  > >
                                  > >
                                  > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                                  >
                                  >
                                  > --
                                  > Julian Smith III
                                  > Rock Hill, SC
                                  >
                                  >
                                  >
                                  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                                  >
                                  >
                                • Manuel del Cerro
                                  ... Best regards, ... Yahoo! Groups Sponsor ADVERTISEMENT Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
                                  Message 16 of 18 , Dec 3, 2002
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                                    on 02/12/02 19:41, Frez at dtetreault61@... wrote:
                                    > >
                                    > >Sorry to get so wordy guys -- I'll try to restrain myself...
                                    > >
                                    > >Dave J.
                                    > >
                                    > >
                                    > >**********************************************
                                    > >
                                    > >--- Please, Dave don't! Informal, friendly chat is the life of this place!
                                    > >>
                                    Best regards,
                                    > >
                                    > > Manuel

                                    >
                                    >
                                    >
                                    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                                    >
                                    >



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                                  • Dave Jackson
                                    Manuel, Thanks -- it s nice to know that at least one member takes the time to wade through what I write. However, I have also heard that my stiff makes a
                                    Message 17 of 18 , Dec 3, 2002
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                                      Manuel,

                                      Thanks -- it's nice to know that at least one member takes the time
                                      to wade through what I write.

                                      However, I have also heard that my stiff makes a great "sleep-aid"!
                                      (Perhaps there are others but they just couldn't stay awake?)

                                      [just kidding...]

                                      Dave J.


                                      **********************************
                                      --- In Microscope@y..., Manuel del Cerro <m.delcerro@a...> wrote:
                                      > on 02/12/02 19:41, Frez at dtetreault61@a... wrote:
                                      > > >
                                      > > >Sorry to get so wordy guys -- I'll try to restrain myself...
                                      > > >
                                      > > >Dave J.
                                      > > >
                                      > > >
                                      > > >**********************************************
                                      > > >
                                      > > >--- Please, Dave don't! Informal, friendly chat is the life of
                                      this place!
                                      > > >>
                                      > Best regards,
                                      > > >
                                      > > > Manuel
                                      >
                                      > >
                                      > >
                                      > >
                                      > > Your use of Yahoo! Groups is subject to
                                      http://docs.yahoo.com/info/terms/
                                      > >
                                      > >
                                      >
                                      >
                                      >
                                      > Yahoo! Groups Sponsor ADVERTISEMENT
                                      >
                                      > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
                                      > <http://docs.yahoo.com/info/terms/> .
                                      >
                                      >
                                      >
                                      >
                                      > [Non-text portions of this message have been removed]
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