Visual Test of Apo with Strehl Ratio 0.96 vs 0.99

I am considering to get a 6" apo, and I am wondering what is the visual performance difference for two of the same high-end apo from AP, Tak, TMB etc with similar interferometric test reports but having slightly different strehl ratios, say 0.96 vs. 0.99? Assume the test results are accurate & reliable. Has anyone done a side-by-side observational comparison at high magnification under excellent seeing condition? This is assuming that all other test variables are same & equal, and testing with an optimised optical train, for eg, just using ZAO-II eyepieces and without diagonals in use. Any feedback or comment would be much appreciated.

LOL, your kidding right? You think you can tell the difference between a .96 and .99 SR? Let me know how that goes for ya.

I would GUESS it's not visible, maybe not even under ideal seeing conditions. Someone like Roland Christen would probably be able to give you a very reliable answer. I remember him once commenting that he doubted anyone would be able to detect the difference between the best of one of his batches and the worst. If memory serves me he places .95 as the lower limit on his finished triplet strehls. So if that's "the worst", and he occasionally achieves .99x (the best), and even he can't see the difference...

My guess is that differences in tube baffling, thermal mass, coatings and other effects would drown out the very small deficiencies of the lower strehl scope.

My guess is the best practical way to judge different apo's is with photography. After all we have been told for a long time that the camera sees far more than our eyes.

This kind of comparison might make sense if the refractors were identical in design and specifications. If you are comparing different designs then all sorts of questions arise about the exact meaning of the Strehl numbers. Wavelength?, monochromatic, polychromatic?, focal length & focus, etc.

Interferograms might tell you something, but good luck at getting that kind of information for amateur gear. 8)

Richard,
I think that the Strehl is a good reference, but only that. Too many factors can influence the test and the results.
If you buy a great brand, like TAK, AP, TMB or Televue, just to name a few, you will probably find that there are only subtle differences.
It seems today that most APOs are made with photography in mind. So they would all be pretty good as cameras are not forgiving when it comes to color correction.
The focal ratio might be a factor for you if you intend to do visual observing. A longer focal length will provide more magnification if that is what you are interested in particularly.