Re: ATM How to find the optical center

["Brian K. Schantz" <bschantz@execpc.com>]

At 09:23 AM 7/8/97 -0400, Bill Fries wrote:

<snip>
>with a spirit level and done in a pair of opposite directions,  90 degrees to
>each other to average out inaccuracies in the level itself. This also assumes
<snip>

What you want to do is reverse the spirit level (rotate it 180 degrees),
and split the difference. Then turn it 90 degrees and repeat. That will
level the mirror along a horizontal plane and remove any errors introduced
by the level.

Brian Schantz
former Air Force surveyor.