|
Distribution of the rings, should be the same inside and outside of focus. The ring pattern in an ideal "perfect" telescope should be the dead set same. I have never seen one that fits this criteria, and I have not yet seen a GS or Synta even approach this criteria. The scopes that I have star tested show very well corrected optics (see Star Testing Astronomical Telescopes by Richard Suiter), but never perfect. There was a great article on telescopes and their performance with steps of 1/8 wave deformation done by Roger Ceravolo in an ATM Journal which was duplicated in an S&T magazine a few years back. Check it out for interests sake.
|