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  1. #1
    Pere Sanz's Avatar
    Pere Sanz Guest

    Default 9mm illuminated reticle box size




    Hi,

    I have a Meade 9mm illuminated reticle guiding eyepiece and want to
    calculate the guiding tolerances. Does anybody know the size of the
    double crosshair box?

    Thanks

    Pere


  2. #2
    Thad Floryan's Avatar
    Thad Floryan Guest

    Default 9mm illuminated reticle box size

    Pere Sanz <peresanz@salbus.es> wrote in message news:<bl1hac$g8sv74@news1s.iddeo.es>...

    The size (in arcseconds) is a function of that eyepiece in your specific
    brand/model scope. For example, in a scope whose focal length (FL) is 900mm
    that eyepiece has a magnification of 100x and in a scope with a 2000mm FL the
    magnification is 222x; the box's size in the FL(900mm) scope is more than twice
    that in the FL(2000mm) scope in terms of arcseconds of sky. In other words more
    "area" of sky is bracketed by the reticule box in the FL(900mm) scope than in
    the FL(2000) scope.

    What you want to do is find 2 stars each of which "sits" on one of the parallel
    lines of the box and look up (or use a chart/planetarium program) the angular
    separation of the two stars and that'll be the box's size in arcseconds for that
    scope. Note you can rotate the eyepiece to facilitate positioning stars "on"
    the reticule lines. Might be easier to do this with "common" doubles for which
    the separations are well known; Albireo might be a good first target to get a
    "handle" on this technique.

  3. #3
    Bob May's Avatar
    Bob May Guest

    Default 9mm illuminated reticle box size

    What does Meade say the size of the box is? That will determine, in
    addition to the focal length of the scope of what the size of the box in
    arcseconds.

    --
    There are more Democrats on the Calif. Special Election than Republicans!
    Go count if you don't believe me!
    Bob May



 

 

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