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: Whole Horizon Mirrors
    From: Geoffrey Kolbe
    Date: 2011 Apr 25, 07:06 +0100
    At 20:44 24/04/2011, Gary wrote:

    50% throughput, on the average for both the horizon and the star for the whole horizon mirror. But for the split mirror almost 100% throughput of the dim horizon and almost 100% reflected of the dim star.


    Ya-but.... When using a telescope of reasonable power only half the light input to the scope is coming from the star and half from the horizon, so there should be no difference whether whole-horizon or split-mirror horizon mirrors are used.

    I can see that when using a sighting tube the eye will see an uninterrupted view of the horizon on one side and of the star on the other. For low power sighting systems the images will not be super-imposed with a split mirror system but at least you will see the star.

    But.... When trying to see faint stars, it would be better to avail yourself of the increased light gathering power of a telescope - would it not? In that case, does it matter which system you use?

    Geoffrey
       
    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