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    Re: Polaris in daytime
    From: Geoffrey Kolbe
    Date: 2012 Jan 26, 18:17 +0000

    Thankyou Dave, your explanation is convincing. Perhaps the thing to
    do is actually stop down the object lens of my theodolite then.
    
    Geoffrey
    
    
    At 15:20 26/01/2012, you wrote:
    
    >Frank is right about magnification being the important parameter in
    >seeing stars during the daytime.
    >
    >For any magnifcation, a star shows as a point source of light in the
    >background of scattered light from the atmosphere. The higher the
    >magnification the smaller the field of view and the less scattered
    >light is picked up.
    >
    >Increased objective diameter picks up more starlight but also more
    >scattered light, no improvement in contrast.
    >
    >The higher the magnification, the smaller the field of view and the
    >harder it is to find the star but as Frank suggests a computer
    >controlled scope will sove that.
    >
    >Dave F
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