[ATM] Which diameter gets worked for a given stroke direction?

[J Killea <jkillea@yahoo.com>]

My 8" f/6.4 appears to have rather different ROCs along 2 perpendicular axes, 2604mm vs 2606mm.  More disturbing is that "b" is about 1.3 for the long ROC axis and about 1.09 for the short (Strehl is .980 for the short ROC, and 0.891 for the long).  So, I would like to get things a bit more even-keeled ( using the average of both axes, of which I took 4 measurement sets each) this mirror is at worst 1/6 wave (spherical wavefront error).  
 
So if I want to work primarily on the one diameter's figure, I am still wondering which direction to stroke.  I can see either argument - stroking parallel to a given diameter changes it preferentially, or the other argument that stroking perpendicular to that diameter is the one that changes its ROC more.  Since we generally talk in terms of surfaces of revolution (which apparently this isn't) we usually don't actually consider what happens in just one stroke.  
 
The strokes I would use would be of even, probably light, pressure.  Clearly when bearing down on a local spot, that spot gets worked more, but that isn't what I plan to do.
 
If you decide to reply (much appreciated!), please use unambiguous language; I think words like "parallel" and "perpendicular" are narrower in meaning than words like "across" and "along" whose meaning can sometimes go either way.  Sorry for the pickiness - just don't want to pester folks with avoidable followup questions.
 
Thanks!
Jay

		
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