Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    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.
    Why?
    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?
    
    Alex.
    
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site