Re: ATM How to find the optical center

[Brian Nestel <blast@aloha.net>]

Richard Schwartz wrote:
> What is the relation between the period of the motion and the focal
> length?  I know it depends on whether the round bead is solid or hollow.
Hi:
Last time I did it was on a 18" f6 with a about 20mm artifical pearl
I didn't measure the period as I was more interested in the end 
product, but its a good question, when I did it I released it about
5" from center so it wouldn't it roll back and forth forever
and when it stopped most of time the spots were almost on top of each
other, rolling friction also has something to do where it stops. Only
once did it stop off center, this was because it stopped on the string
hole. I am going to be doing a 8" f6 soon and will make a period 
experiment. BTW real pearls are worthless because they are not
really spherical.
-- 
Aloha   159 36 W, 21 58 45 N
Brian   Middle of the Pacific,
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