Re: [ATM] Stubborn TDE

["Jerry" <wa4guu@verizon.net>]

Maybe you did not put the accented pressure in the right place. Closer to
the edge might work. Or maybe just a bit on the other side of the edge.

You put the pressure on the area just inside the turn down and made it
worse. You probably thought that you would wear that area to a longer radius
more like the edge. Sounds like it should work... but it went the other way.
Accept what really happens when you do that and think about where you could
apply the same action that would produce the same result it did before but
in the right place.

The zone you put the pressure on will shorten in radius compared to the zone
outside the work. The correction from the zone inward to the one worked will
be reduced.

Some strange logic says to me that if your edge had been 1/2 inch closer to
the center of the mirror, what you did would have improved the edge.

Jerry

 


-----Original Message-----
From: David Steinhauer
 
I've been trying to get rid of the TDE in my 6" f5 mirror, without success.

Here's my original Ronchi photo, before I tried tackling the TDE.  It is 
quite spherical, but has a
narrow TDE.  Note that all my Ronchigrams are outside of focus, and all 
my KE photos have the
knife edge approaching from the right.
http://www.atmlist.net/contrib/desteinhauer-at-verizon-dot-net/060829_6inch/
060521-Ronchi1-sm.JPG

First I tried using accented pressure just inside the edge, with TOT.  
All I did was increase the TDE
and create a central hill:
http://www.atmlist.net/contrib/desteinhauer-at-verizon-dot-net/060829_6inch/
060529-Ronchi-sm.JPG
http://www.atmlist.net/contrib/desteinhauer-at-verizon-dot-net/060829_6inch/
060529-KE-sm.JPG



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