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    Re: Dipmeter: was [NAV-L] Wires, back sights and collimation
    From: Alexandre Eremenko
    Date: 2004 Dec 1, 19:01 -0500

    And another related question:
    On Wed, 1 Dec 2004, Frank Reed wrote:
    > why do they never fix  the
    > mirrors rigidly on a sextant,
    > Presumably because the mirrors have to be re-silvered now and then.
    The older sextants apparently had collimation adjustment.
    The newer do not.
    One can argue that this is because with modern technology
    they can make sure that the telescope mounting is rigid
    enough... But then another interesting question
    SNO-T is produced with two telescopes:
    7x30 inverting (Kepler) with wires, and
    4x50 upright (Galileo) like on most modern sextants.
    The inverting one has collimation adjustment while
    the upright one has none. The mountings are of course
    absolutely similar.
    Is this related somehow with higher magnification
    of the inverting scope? But then why the 6x or 7x prismatic scopes
    of modern sextants don't have it?

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