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Re: Sky-90

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  • KC Kong
    Tony and All I have uploaded 2 drawings of Sky90 in the Sky 90 file. KC Kong ... click on ... right to ... will even ... to me
    Message 1 of 35 , Nov 1, 2000
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      Tony and All

      I have uploaded 2 drawings of Sky90 in the Sky 90 file.

      KC Kong

      > KC,
      > Thanks for the info. You can go to the home page for this list and
      click on
      > files. Once you are on the page there is a link for posting images
      right to
      > the groups files so anyone wanting to see can go there and look. It
      will even
      > send a post to us telling us of the new post.
      > If you have any trouble with this feel free to e-mail a jpeg image
      to me
      > privately and I will post it for you.
      > Best,
      > Tony
      >
      > ANTHONY D. MILLER & Co.
      > ~ The Tintype Artist ~
      > Ambrotypes & Ferrotypes
      > 34 Perryfalls Place
      > Baltimore, Maryland 21236
      > 410-256-7442
      > www.tintype-artist.com
    • Gene Horr
      ... The index of refraction is not exactly the same for each filter. The difference is minor, but changing filters requires a slight tweak of focus. ... For
      Message 35 of 35 , Nov 2, 2000
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        "Lawrence M. Geary" wrote:

        > It isn't obvious to me why a color filter would change the focal position.

        The index of refraction is not exactly the same for each filter. The
        difference is minor, but changing filters requires a slight tweak of
        focus.

        > If so, then I have a problem with my eclipse photography technique (Questar
        > 3.5"), because I focus on the sun using a filter, then of course remove it
        > for totality.

        For this I wouldn't worry about it.
        1) You aren't dealing with point sources and if the focus is off 1/500" you
        probably couldn't even notice the difference
        2) I assume you are doing film photography. Since you are dealing with
        a curved field anyway any focus shift is merely moving the ring
        of perfect focus.

        Gene Horr
        genehorr@...
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