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: Lunar contrast
    From: Geoffrey Kolbe
    Date: 2016 Sep 11, 19:46 +0100

    Where would be the best location for a polarizer in the sextant's light path?

    ​ ​
    I taped a polarizer directly to the objective end of the sextant telescope.

    When the moon is waxing you would want to view the moon through the horizon mirror so the handle of the sextant will be underneath the sextant. When the moon is waning, you will want to view the moon through via the index mirror for the same reason. ​It follows that either of the mirrors is NOT the place to put the polarizing element. The rubber eyepiece of the sextant might have a little lip around it in which a small glass or plastic filter element can be placed. Otherwise, polarizing elements for cameras can be obtained for very reasonable prices in many different diameters and some means of fixing these in front of the object lens can be contrived. Once in place and adjusted, it probably need never be removed.

    ​Geoffrey Kolbe​

       
    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