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: Navigation instruments from Paris, Maskelyne
    From: Brooke Clarke
    Date: 2004 Jul 20, 21:02 -0700
    Hi Peter:

    Although the screen resolution limits what  you can see in one frame, that does not mean you need to limit photos to a screen size.

    I've found that the best results come from starting with the highest resolution image you can muster, say 6 mega bytes from my camera, or 25 mega bytes from the flat bead scanner (which does a very nice job on many 3 dimensional objects).  Then do the cropping, background erasing, etc. in photoshop (or the OEM free version photoshop elements), then make one jpg at the highest possible resolution, and another where the DPI is around 60 to 70 and use the "medium" jpg compression.  This last "small" version might have a linear dimension of a few inches and will look nice on the computer screen.  The small image can be linked to a larger image so when you click on the thumbnail you then see the larger image and it's all on screen.  But when you mouse over that image the cursor tip changes to a "+" and when you click in the image it expands.  This allows seeing all the very fine detail.

    For an example go to my product page:
    scroll down to the CLP-PP (Cigarette Lighter to Power Pole cable) and look at the image.
    Then click on the image to get to the next size up on a new page.
    Now click on that image to see very fine detail.
    This image was made using a scanner and the process described above.  I don't remember the original file size, but would guess maybe 6 mega bytes.

    Have Fun,

    Brooke Clarke, N6GCE


    Peter Fogg wrote:
    Photoshop is the most well known (and possibly the most demanding to use well) image management
    software. Since computer screens only output at about 72 pixels per inch (they vary) there usually is no
    reason to send pics for viewing on a monitor at a resolution any higher than this. In Photoshop,
    choose 'image size' then save a copy of your pic at this resolution and at an appropriate size for viewing.
    Then convert it to .jpg file format, but only after you have completed all other operations, as this step
    loses image quality each time, the effects are accumulative. If your camera records in .jpg then convert to
    another lossless format as the first step, then reconvert as the last. I wouldn't be surprised to learn that
    there is software freely available that could do all this. Photoshop is really a professional application and is
    quite expensive, although there are different versions available.
    "how to diminish them and not to degrade them too much" Photoshop certainly has wonderful tools. One of
    the most useful is a histogram, called 'levels', which is like a statistical map of the amount of dark and light
    tones. Almost every picture can be improved by playing with its 'levels'. But this is hardly scratching the
    surface of what is possible with computer image manipulation. There is much information online. Its a big
    Quoting Jan Kalivoda <Jan.Kalivoda@FF.CUNI.CZ>:
    Hello, Joel,
    thank you for your remark. I am fully aware of your troubles, but working
    only from internet cafes in Paris, I cannot help you and me now. I will be
    able to redress and republish my pictures only in August from Prague.
    Meanwhile, can you give me advice about software and modes that shall I use?
    I tried higher compression ratios for these JPG's, but the quality suffered.
    And as these pictures are not the best even uncompressed (it was a bit
    difficult to take them in an unsuitable room, deep behind the glass), I
    wonder, how to diminish them and not to degrade them too much.
    Thanks, Jan Kalivoda
    Joel Jacobs writes:
    Hello Jan,
    Thank you for the invitation. But, the file sizes of you pictures average
    about 2 Megs. For some of us they take too long to load even with
    Simple photo editing software would allow you to get the file size down to
    20 KB and still have good pictures.
    BTW, The first picture is still working on opening.
    I very interested in what you published, but haven't more time,
    Joel Jacobs
    ----- Original Message -----
    From: "Jan Kalivoda" <Jan.Kalivoda@FF.CUNI.CZ>
    Sent: Monday, July 19, 2004 5:39 PM
    Subject: Navigation instruments from Paris, Maskelyne
    if anybody wants, login to "http://www.xdrive.com" under the login
    "navigation@seznam.cz" (XDRIVE allows only valid e-mail addresses as
    as you probably know), password "celnav".
    You have 60 MB photos of some historical navigation instruments kept in
    Marine Museum in Paris (directory "Musee de la Marine") there. I tried to
    create the logical sequence of them from the nocturnal and the Jacob
    to repeating lunar circles.
    Of course, I am not a professional photographer and I didn't have the
    instruments available "au plain air".
    At the end of this week, I shall obtain some copies of Maskelyne's less
    known works printed in the 18th century. It would be interesting to chat
    about them a bit in the list.
    Jan Kalivoda

    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