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Re: DCL-52 & TV85

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  • danieldgj <danieldgj@yahoo.com>
    The point is, no flattening is necessary for through-the-eyepiece photography. The field of a good refractor such as a TV85 is flat across the reltively small
    Message 1 of 5 , Mar 1, 2003
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      The point is, no flattening is necessary for through-the-eyepiece
      photography. The field of a good refractor such as a TV85 is flat
      across the reltively small area of typical eyepiece fields, and that
      is what your camera will see. If your eye sees pinpoint images
      through an eyepiece, so will your camera. If you can see pinpoint
      images across the eyepiece field visually but they're blurred in your
      digital photos, then either you're out of focus or the camera itself
      has optical aberrations. Field flattening is necessary only for very-
      wide-field film photography, or for the use of very-wide-field
      eyepieces such as Al Nagler's biggest monsters. Worst case scenario:
      you'll have good images at the center, but a bit of blurring at the
      edges. In practice, there are many other things that will be more
      limiting to your digital photos with a Coolpix (vignetting, thermal
      noise on long exposures unless the temperature is below freezing,
      etc.), and I suspect you'll find that the TV85 has fewer aberrations
      than your camera.

      --- In William-Optics@yahoogroups.com, "davetyrer <davetyrer@y...>"
      <davetyrer@y...> wrote:
      > Hi Daniel
      > I expect the DCL-52 is the eyepiece you are talking about. see this
      > links. Would this eyepiece help flatten the field then?
    • davetyrer <davetyrer@yahoo.co.uk>
      Thanks for the explanation Daniel now I understand, but I ve just managed to get my hands on an NP-101 which is already flatfield so it s not much really an
      Message 2 of 5 , Mar 1, 2003
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        Thanks for the explanation Daniel now I understand, but I've just
        managed to get my hands on an NP-101 which is already flatfield so
        it's not much really an issue any more. Hopefully I'll have it by
        next weekend - only problem is my mount isn't available for 2
        months - cel la vie!



        --- In William-Optics@yahoogroups.com, "danieldgj <danieldgj@y...>"
        <danieldgj@y...> wrote:
        > The point is, no flattening is necessary for through-the-eyepiece
        > photography. The field of a good refractor such as a TV85 is flat
        > across the reltively small area of typical eyepiece fields, and
        that
        > is what your camera will see. If your eye sees pinpoint images
        > through an eyepiece, so will your camera. If you can see pinpoint
        > images across the eyepiece field visually but they're blurred in
        your
        > digital photos, then either you're out of focus or the camera
        itself
        > has optical aberrations. Field flattening is necessary only for
        very-
        > wide-field film photography, or for the use of very-wide-field
        > eyepieces such as Al Nagler's biggest monsters. Worst case
        scenario:
        > you'll have good images at the center, but a bit of blurring at
        the
        > edges. In practice, there are many other things that will be more
        > limiting to your digital photos with a Coolpix (vignetting,
        thermal
        > noise on long exposures unless the temperature is below freezing,
        > etc.), and I suspect you'll find that the TV85 has fewer
        aberrations
        > than your camera.
        >
        > --- In William-Optics@yahoogroups.com, "davetyrer
        <davetyrer@y...>"
        > <davetyrer@y...> wrote:
        > > Hi Daniel
        > > I expect the DCL-52 is the eyepiece you are talking about. see
        this
        > > links. Would this eyepiece help flatten the field then?
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