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    Re: Dip Variation by Theodolite
    From: Bruce J. Pennino
    Date: 2014 Jan 3, 17:09 -0500
    
    Hello:
     
    I just check the specifications for the total station: magnification = 30x ; field of view 1 degree 20 minutes. Does this make it to easy? 
     
    Frank, by the way , I'm glad you remembered that we made the vertical angle exactly 90 degrees. Not in my notes.
     
    regards

    Bruce
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
    ----- Original Message -----
    From: Frank Reed
    Sent: Friday, January 03, 2014 4:33 PM
    Subject: [NavList] Re: Dip Variation by Theodolite


    Many of you may recall that Bruce Pennino brought his total station (theodolite) to Beavertail Point at the southern end of Conanicut Island a couple of months ago. We experimented with measuring height of eye and he demonstrated his direct measurements of dip. A large car carrier was headed in, getting ready to sail up into Narragansett Bay, and anchored briefly south of Newport. Bruce aimed the theodolite at the ship for a better look, and I held my phone up to the ocular to snap a few photos. Smartphone cameras take very nice images by this direct eyepiece projection technique since they have infinite focus by design. Here's a photo showing the big ship and the crosshairs. Given that the horizontal crosshair line sits on the true horizon, what can you figure out about this ship and other aspects of the observation? How far away is the ship? How big is it? Do you need to know height of eye (about thirty feet) to figure that out from this photo?

    -FER
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