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    Re: planned purchase astra IIIB
    From: Alexandre Eremenko
    Date: 2007 Jan 28, 20:51 -0500

    
    On Sun, 28 Jan 2007, coralline algae wrote:
    
    > Upon delivery what should I look
    > for to insure that there are no major
    > problems with the instrument.
    
    Visually inspect all parts to be sure that
    they are unbrocken, that everything which should move
    moves smoothly, and what should not move does not move.
    Try to shake the (clamped) index arm with your hand in
    both directions. It should not shake.
    Check and adjust perpendiculatiry of mirrors.
    Check collimation. (This is not adjustable on Astra!
    If it is out of collimation, return it).
    Determine the IC.
    Then do it again, sextant uspide down
    Then two more times, sextant horizontal.
    It should be the same in all positions.
    Check for backlash.
    
    Finally take some sights from a known position and
    reduce them.
    Take some star distances.
    
    On traditional versus full-view mirrors.
    I feel that traditional mirrors are better.
    They are certainly better for all twilight
    observations. And in the daylight they have no substantial
    advantages. With a 6-8 scope, the picture you see is
    practically the same. With the ordinary scope, traditional
    mirror requires a bit more practice,
    but I do not thing this justifies a full-vew mirror.
    
    Alex.
    
    
    
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