Anyone wanting a less biased appraisal of performance might find these interesring:
https://www.cloudynights.com/topic/5...luorite-vs-ed/
And this comprehensive look at various objective materials in combination (note the Strehl figures from #15 onward).
http://telescope-optics.net/semiapo_...o_examples.htm
Eddgie's examples of comparative Strehl figures for FPL-53 and Flourite are worth a look, see posts # 13 and 14 in the CN thread.
What i take from the chart is that any historical (or hysterical) flourite advantage is no longer relevant if your choosing FPL-53, even to my guide dog,