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    Re: Lunar Scopes
    From: Fred Hebard
    Date: 2005 Feb 13, 23:49 -0500

    On Feb 13, 2005, at 11:10 PM, Frank Reed wrote:
    > Fred you wrote:
    > "There are no alignment adjustment screws in the mounts of all prism
    > scopes of which I am aware. "
    > If I have it right then, the feature that you like about the inverting
    > scopes is not that they're inverting but he fact that they have
    > adjustable alignment (which would make good sense). Yes?
    > And:
    > "If it's out, there's nothing you can do to
    > bring it back.  I bought one about a year ago that was out. "
    > Interesting. Were you able to estimate by how much? Also, I realize
    > that this is a "low-class" solution but did you experiment with
    > shimming it?
    > -FER
    > 42.0N 87.7W, or 41.4N 72.1W.
    > www.HistoricalAtlas.com/lunars
    First, perhaps an expert would know how to adjust the collimation on a
    modern prism sextant scope.  But I see no screws for doing that on
    mine, and disassembled it and examined it carefully.
    I don't think shimming would work.  The fork is u-shaped piece that's
    bolted to the tube of the scope; it's quite narrow and custom cut to
    fit the tube.  I suppose I could grind it, but I'm no instrument
    I'm guessing my prism scope was out about 4 inches at about 20 feet,
    about a degree.
    As well as being adjustable, the SNO-T additionally has cross hairs and
    is reasonably light, since lacking prisms.
    My main point was to check any scope before doing lunars or other
    high-precision work.  I believe Joel Jacobs would allow return on an
    item were it unsatisfactory.

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