Re: [ATM] RE: [atm_free] The zonal Foucault test isfreeofinherentcorrection bias - some supporting graphs

["Bob May" <bobmay@nethere.com>]

Read the last paragraph of Linfoot's treatise and you will note one little
comment on reading the zones where he says that you want to be looking at
the zones as the knife cuts the beam for which side darkens first.  It seems
that a lot of people think that reading the zone by strict comparing of the
two shades of gray as a static display as the camera will show is the way to
do it but I think that watching the two zones as they darken as Linfoot says
is the more proper way to do the test.
With the static setting of the KE, you are comparing two brightness levels
which may or may not be exactly right.  Watching the shadow flicker across
the two zones is something that the eye can spot a lot easier as which one
starts and finishes first.  I can get to within maybe .003" by comparing the
two zones by a static display but get a lot closer when looking at how the
two zones flicker dark and light when the KE is moving.  I suspect that
James is doing it this way to get the half thou readings that he is
claiming.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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