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Re: [atm_free] Re: Sun testing a polished mirror

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  • jc.v@sympatico.ca
    Hugues, Tu as eu les bonnes explications. Je suis québécois, on pourra s en parler en privé dans notre langue. Amités Hi everybody, have agreat day.
    Message 1 of 4 , Mar 1, 2003
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      Hugues,
      Tu as eu les bonnes explications. Je suis québécois, on pourra s'en parler en privé dans notre langue.
      Amités
      Hi everybody, have agreat day.

      Jean-Charles


      > De: "Ken Hunter <atm_ken_hunter@...>" <atm_ken_hunter@...>
      > Date: 2003/02/28 ven. AM 11:10:57 GMT-05:00
      > À: atm_free@yahoogroups.com
      > Subject: [atm_free] Re: Sun testing a polished mirror
      >
      > Mark...
      >
      >
      > NOT TO WORRY!
      >
      > The sun would produce a point focussed dot if it were itself a point
      > focussed dot like any other star. Unfortunately for testing scopes,
      > (fortunately for us) it is MUCH closer and shows up as an extended
      > object here on this planet. It is about 1/2 degree wide and there is
      > a formula for figuring the extended angle that it should be at the
      > focal plane. I'm at work now so don't have it handy but I suspect
      > that your are seeing the correct view which will also be the size of
      > the moon when imaged by your scope.
      >
      > Ken Hunter
      >
      > --- In atm_free@yahoogroups.com, "mschaffroth <mark.schaffroth@t...>"
      > <mark.schaffroth@t...> wrote:
      > > Hello.
      > >
      > > I'm about finished polishing my 8" f/7 blank and took it outside to
      > > see how it focuses the sunlight. I was surprised (and a bit
      > > concerned) that the smallest spot it could make was about the size
      > of
      > > a dime (1.2cm), or perhaps a bit smaller. I thought it would make
      > a
      > > pin point dot. Is what I'm experiencing expected and does it
      > > indicate anything about the quality of my blank?
      > >
      > > About half way through my polishing I looked at the Ronchi lines
      > and
      > > they all looked parallel, but somewhat fuzzy around the edges.
      > >
      > > Thanks!
      > > Mark S.
      >
      >
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