Quote:
Originally Posted by Peter Ward
John,
So are you saying test data provided by (skilled) opticians is some sort of random number that in no way correlates to the quality of the optic?
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I am saying the numbers are a lot less relevant and meaningful than many people perceive. They are good to compare optics tested by the one person, under identical test conditions. They are not good to compare optics made and tested by different people under different conditions, because of inconsistency in test methods and test conditions.
Quote:
Originally Posted by Peter Ward
In fact Ceravolo did a piece for Sky and Telescope (March 92?) where telescopes with mirrors of varying (but known) quality were used side by side to see if anyone could tell the difference visually.
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The article did appear in the March 1992 edition of Sky and Telescope. It was in fact a joint article by Peter Ceravolo, Terence Dickinson and Douglas George. I have read it many times.
Quote:
Originally Posted by Peter Ward
In this case the numbers were not just relevant, they demonstrated perfectly the difference between "bad, fair, good and excellent optics"
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Of course they demonstrated things perfectly. All the mirrors were made and tested by the same skilled person (Ceravolo) on the exact same equipment, using the same methods and conditions. This is the exact point I am trying to make and that Aster, Mark and others also referred to, and you are missing.
Cheers,
John B