ATM Spot marking the secondary

[Billy Rudock <Billy_Rudock@notes.seagate.com>]

The ATM archives (7/95 and 3/96) cover spot marking the secondary mirror to aid 
in collimation.  Since the discussions were "lively", I would appreciate a 
quick confirmation to my understanding of the method.  

(my simple scope:  8" f/6, 1.83" secondary)  
1. the dot is placed on the optical center (using an offset) of the secondary 
mirror, not the geometrical center.  
2. since the offset is away from the focuser and down towards the primary 
mirror, the optical spot mark ends up being slightly higher (on the mirror's 
center line) than the geometrical center.  
3. in use, the new secondary spot is centered exactly underneath the sight tube 
crosshairs.

(Since the calculated offset for my setup is ~.07", is it noticeable?)  Thanks 
for the terrific help!

Chin and eyes up!
Billy Rudock
Santa Cruz, CA