Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Which diameter of the sun in digital photos ?
    From: Greg Rudzinski
    Date: 2009 Aug 21, 13:25 -0700

    Yes I have compared and cross checked DSLR vertical and horizontal
    terrestrial angles with Sun diameter measurements. I haven't had any
    problems getting 2 minutes of arc accuracy (precision about 1 MOA) or
    better using a 50mm lens. I confidently trust the digital camera
    celestial navigation concept for practical use aboard small craft even
    in rough weather.
    On filtering: If the circular polarizing or neutral density filters
    are hand held in front of the lens so that only the Sun is filtered
    and not the horizon then you should get some useful images.
    One other thing to try is the varying of exposure with photo software.
    The changing diameter of the Sun with over exposure is obvious during
    this manipulation process.
    On Aug 21, 12:38�pm, Marcel Tschudin 
    > Greg, thank you for your suggestions.
    > For this exercise I'm using always the same camera having always the
    > same lenses.The sun's diameter is measured in a photo-program after
    > removing all colours except green and in some cases even removing all
    > but blue. I fear to put an other hand-held filter in front since I
    > have to measure the distance to the horizon which still must be
    > visible, since the main purpose is to measure the sun's distance to
    > the horizon. I have so many only faintly visible sun pictures
    > confirming the obtained scale that I'm fairly confident that the value
    > corresponds to what the camera 'sees'.
    > Have you ever tried with the same lenses to compare the pixels per
    > degree you obtained for the sun with those of landscape features?
    > Marcel
    NavList message boards: www.fer3.com/arc
    Or post by email to: NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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