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  1. #1
    MJ Eickhoff's Avatar
    MJ Eickhoff Guest

    Default How to determine barlow magnification



    I recently acquired a used 3.5 Questar. Does anyone know of a good way to
    to determine the magnification provided by the internal barlow? Is it as
    simple as observing the field width and if the barlow causes the field to
    shrink to 1/2 the diameter, it is 2x, if it causes the field to shrink to
    2/3 the diameter, it 1.5x? I'm about to venture forth to find a nice long
    railing with vertical slats to sight on. If there is trick to doing this,
    I'd appreciate learning about it.

    Thanks in advance,
    Mark



  2. #2
    Daniel Drabek's Avatar
    Daniel Drabek Guest

    Default How to determine barlow magnification

    The internal barlow in the 3.5 Questar doubles the magnification of the
    eyepiece.

    In article <gHVNc.17$U_3.9100@news20.bellglobal.com>,
    "MJ Eickhoff" <mjeick@sympatico.ca> wrote:


  3. #3
    William Hamblen's Avatar
    William Hamblen Guest

    Default How to determine barlow magnification

    On 2004-07-28, MJ Eickhoff <mjeick@sympatico.ca> wrote:


    The field of view is inversely proportional to the magnification, so
    your idea works. Besides using a fence, you could point the Questar at
    a star near the celestial equator, turn off the star drive and measure
    the time it takes a star to cross the field of view. The built in barlow
    is supposed to be about 2x, but that can vary.


  4. #4
    MJ Eickhoff's Avatar
    MJ Eickhoff Guest

    Default How to determine barlow magnification

    That's what I thought too, but I've subsequently read it could be 1.5x
    or/thru 2x. It looks to be more like 1.5x to my eye. Not knowing just
    slays me.

    Mark
    "Daniel Drabek" <danieldNS@cruzio.com> wrote in message
    news:danieldNS-764197.21570128072004@cnews.newsguy.com...
    to
    as
    to
    to
    long
    this,



  5. #5
    MJ Eickhoff's Avatar
    MJ Eickhoff Guest

    Default How to determine barlow magnification

    Thanks - Your star drift approach will be more accurate and will involve
    less travel.

    Greatly appreciated.
    Mark
    "William Hamblen" <william.hamblen@comcast.net> wrote in message
    news:ZbidnaX8V-Ga8pTcRVn-hg@comcast.com...
    to
    as
    to
    to
    long
    this,



 

 

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