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    Re: Positioning of 7 x 35mm monocular on Astra IIIB sextant
    From: Bill B
    Date: 2012 May 10, 18:27 -0400

    On 5/10/2012 1:28 PM, Alan S wrote:
    
    > 1. I have an Astra IIIB, which came with a 3.5 x 40mm straight scope. No
    > problems with it, other than the sometimes questionable nature of my
    > sextant technique.
    
    I have the same set up. Love Celestaire's 7 x 35.  Tack sharp. Nice job Ken.
    >
    > 2. I recently purchased a 7 X 35 mm monocular. There is a dimensional
    > difference between the mounting brackets on the two scopes which if you
    > will bear with me on a semantic point, I will describe as "two tined
    > forks". The length dimension of the monocular's fork is, as I measured
    > it, 5/16" longer than the mounting fork on he straight scope.
    
    The fork tines are indeed longer on the 7x35, and the slot is deeper
    too. That is not really important if the distance from the center of the
    scope to the interior end (closest to the scope) of the slots are equal.
    I did a quick check, and both the 3.5 x 40 and 7 x 35 are approximately
    equal; about 15mm.
    >
    > 3. How should one position the monocular on the sextant so as to get a
    > proper horizon image, respecting the dimensional difference betwween the
    > mounting forks?
    
    If Celestaire, just put it all the way until it touches the lug and you
    are good to go. If the scopes' center to slot end distances are
    different, then Greg's idea is a good solution.  I do find it is
    important to look down the center of 7 x 35 scope, or the glass/mirror
    image split can shift quite a bit--much more so than with the 3.5 x 40 IMHO.
    
    Bill B
    
    
    
    

       
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