From: "Dwight K. Elvey" 
To: atm{at}shore.net
Reply-To: "Dwight K. Elvey" 


>From: "James Lerch" 

---snip---

Hi James
 When I measure by eye, I don't set a predetermined
intensity. What I look for is that a particular zone grays at the same rate
from both sides as I move the edge laterally. This seems different than
what your code is doing.
 Perhaps you can do the same by measuring several pictures
as you move the lateral position of the KE and look to see what zones on
both sides change at the same rate. You should find that on either side of
the correct zone, the light will be stagered when the intensity changes.
One side will lead and the other will lag. The two sides don't even have to
be the same exact intensity since errors in the camera and light source
contribute to this while the change rate is only related to the zones
distance from KE. You can even normalize the curves from total illumination
to total dark to compensate for any errors.
 I realize that this is quite different than what you
are doing but it is the only way that I've been able to finely pin down
Foucault readings. Dwight

Some ascii art follows:

Light curves for zones with lateral KE motion:

Zones not matched:

   ____
R      \_____
   _____
L       \____


Zones matched:

   ____
R      \_____
   ____
L      \_____

--- BBBS/NT v4.00 MP