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Re: [Microscope] Thoughts on resolution and resolution testing

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  • Mike Whittome
    A suggestion for you that may or may not work, satisfy your goal.   Try finding a small piece of paper, one that has been run thru a copy machine, that has
    Message 1 of 49 , Aug 1, 2008
      A suggestion for you that may or may not work, satisfy your goal.
       
      Try finding a small piece of paper, one that has been run thru a copy machine, that has "dithered" printing on it and see if the scope with better clearity can resolve items on the paper that the others cannot.
       
      The printing I describe is usually on copies that were not flat on the glass and have that shadowed or dither greyed or slightly blacked areas.
      This will be printed, scattered very fine particles adheared to the paper. If the resolution and clearity is good, you will most likely see more items of smaller size. The scope that is less clear and has lower resolving power, will meld the smaller particles into gray diffused marks barely discernable. You can use the good scope to circle these areas with a good fine tip pen so you know the locations. Keep you test sheet in a safe container that will go in your pocket. Perhaps a small plastic box etc.
       
      Just an idea......
       
      Regards,
       
      Mike

      --- On Thu, 7/31/08, David L. Jones <dljones@...> wrote:

      From: David L. Jones <dljones@...>
      Subject: Re: [Microscope] Thoughts on resolution and resolution testing
      To: Microscope@yahoogroups.com
      Date: Thursday, July 31, 2008, 3:58 PM






      Don,

      What I was trying to do is quite simple, in concept. I was looking to
      evaluate, through quantifiable measurements, the difference between 3
      different stereo microscopes that are at three different locations (that
      later became two as the third one is now unavailable) .

      I have found I can easily quantify both field of view and depth of field.
      But when I was doing that, I discovered that my quite old Nikon stereo
      microscope had a "clarity" of image that was "noticably" superior to the
      "clarity" of image of a brand new AmScope that was just purchased.

      This noticable difference led to the question of how could I quantify this
      difference and the idea to quantify the resolution of the instrument
      became the new subject. To quantify the resolution of a stereo microscope
      is also quite simple, in concept. But unless you own a target that has a
      fine enough structure, it will be difficult to do across a wide range of
      stereo microscope geometries and locations. The stumbling block here is
      essentially money.

      Mattbrin came up with a very interesting way to do it optically, but a
      mirror system is needed that I don't have although I'm seeing about trying
      to put one together. That method however, is not easily portable and I
      originally was thinking I'd like to do it with two or three items in my
      shirt pocket that I could use on whatever microscope I might happen to run
      across, like at a flea market or auction, etc.

      dj

      On Wed, 30 Jul 2008, DonH wrote:

      >
      > Hi all,
      >
      > I've been skimming this thread off an on, given my limited time. It
      > raises the question: what are you trying to do with the stereo scope?
      > Most stereo scopes are used at relatively low power to view features of
      > 3D specimens. I find depth of field, flatness of field of view,
      > chromatic aberration, usability features, and working distance far more
      > important than absolute flatfield resolution.
      >
      > The perceived resolution will vary depending upon the surface texture of
      > the 3D object. I often look at small minerals, which have a lot of
      > depth and drastic surface topography. I run out of depth of field long
      > before I run out of resolution. If I ever buy another stereo scope, I
      > am going to pay attention to the nominal depth of field specs more than
      > any other optical property.
      >
      > So then, it is a matter of asking yourself if you need such a fine-scale
      > resolution test in the first place. Just food for thought.
      >
      > Good luck,
      > Don
      >
      >
      >
      >
      >
      >
      > ------------ --------- --------- ------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >

















      [Non-text portions of this message have been removed]
    • mattbrin
      ... tell, ... You neglected to mention the price: $3300 not traceable and without the recommended $200 retaining ring. However, this is will within the
      Message 49 of 49 , Aug 4, 2008
        --- In Microscope@yahoogroups.com, "David L. Jones" <dljones@...> wrote:

        >
        > The MRS-5 standard that they are also working on is, as far as I can
        tell,
        > not very useful for light microscopists but is really made for
        >ultra-high
        > resolution instrumentation. But if anyone is interested, here's the
        >link
        > to that standard as well:
        > http://www.gellermicro.com/mag_standards/MRS-5_1-brochure-prelim.pdf
        >

        You neglected to mention the price: $3300 not traceable and without
        the recommended $200 retaining ring. However, this is will within the
        typical rate of $1 per line per mm since the smallest target is
        pitched at 12,500 lines/mm. Quite a bargain.
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