From: astroelectronic@t-online.de   
      
   Phil,   
      
   I did make some raytracing simulations and came to the conclusion that it   
   doesn't care on which surface an aberration is produced. The result in the   
   focal plane is always the same. One wave of spherical aberration in the   
   eyepiece gives the same result as    
   one wave of spherical aberration in the telescope mirror. One wave of   
   astigmatism produced near the secondary in a Newton telescope gives the same   
   result as one wave of astigmatism in the primary mirror.    
   Under the assumption that the Zernike polynomial is defined over the acutal   
   diameter of the light cone at that surface.      
   http://www.astro-electronic.de/Zernike_in_Systems.pdf    
      
   Michael   
      
   --- SoupGate-Win32 v1.05   
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