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    Re: Positioning of 7 x 35mm monocular on Astra IIIB sextant
    From: Ken Gebhart
    Date: 2012 May 10, 21:31 -0500

    Bill,
    
    Thanks for the comment. Coming from you it is a real complement.
    The scope itself is an exact clone of the (now defunct) Tamaya scope,
    except for the best optics we could find. It should fit on Tamaya,
    Plath, and Astra sextants, with some attention to positioning by the
    user so that he will be looking through the center of the horizon
    mirror.
    
    Ken Gebhart
    On May 10, 2012, at 5:27 PM, bill wrote:
    
    > 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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