Quote:
Originally Posted by Peter Ward
John,
When Jones, Ceravolo Christen et al. tell me an optic has a Strehl of 0.96, while you may not accept it, I tend to believe them.
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Peter,
I also believe them as it relates to a relative measure with all the other items they each have tested and certified. My point is this. Is a Ceravolo optic of strehl .98 better than a Christen Optic of .97 strehl? Be rest assured you don't know, I don't know, and most importantly, we are unlikely to get seeing conditions good enough to tell them apart more than once a decade, if we are lucky. The only way to tell them apart is if the one optician was to test both optics under the same conditions and on the same equipment. Consequently, as a relative measure the numbers don't mean much.
I am about to order a mirror from Mark and I won't have a clue what the strehl number is; and I don't care. Suffice to say that I have looked through enough of his mirrors and mirrors from a lot of other premium opticians, to know that he doesn't make any "bad" ones. In fact he is easily in the top 10 glass pushers on the planet and that is more comfort to me than a piece of paper with a number certified under variable test conditions. Similarly, if I buy an optic made by Christen, Zambuto, Steve Kennedy or Peter Ceravolo, I don't need to look at the strehl number to know that it's as good as hands can make it and I am happy to buy it.
Cheers,
John B