NavList:

Bill wrote:

>> I do feel confident that the astigmatisms play a large role in
>> the shift from tangent horizontal vertical to tangent
>> horizontal.  That I can see, and to some degree measure.
>>
Richard replied:

> Now if there were only some easy way you could keep the position
> of the sextant the same, and tip your head from upright to
> horizontal, then you would be testing only the astigmatism of the
> one eye.  A clamp and sturdy tripod, perhaps?

That's some very nice thinking.  I have the equipment (photo kludge) and
have used it in my earlier and more shaky days.  I can do that with relative
ease, with the minor exception of keeping tangency in the middle of the
scope over any prolonged period of time.  Your experiment should not take a
prolonged period of time.

If I understand, that will eliminate any possible vertical/horizontal,
frame/mirror/gravity effects and get it down to my eyeball/optical system.
(Old neck a bit stiff about now, but what the heck.)

Thank you so much,

Bill


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