Actually I do care about performances, and only about them -- those are given (also) by the glass. But not a fancy-labelled one, rather the combination of all of the elements composing the objective lens.
If your 102 f/11 FPL51-flavoured gives better chroma correction that your Stellarvue 102 Access FPL53-empowered, that simply means that the designer of the former did a better work than the one of the latter; and the lens executor(s) did a better job in figuring it. FPL51 vs FPL53 being just a part of the equation.
All things being equal -- same mating element, same f/ratio, same spherical, same mechanics -- FPL51 objectives do show more CA than their FPL53 counterparts. But "all things" are never "equal".
People on this forum and elsewhere seem to like cheap shortcuts to self-pride of ownership, calling it "knowledge". But, if you carefully select the mating element, if you use a slightly longer f/ratio, if you are more careful with the spherical (longer f/ratio helps in that AND in better spherochromatism as well), and you have a better mechanics (which is also helped, again, by the slightly longer f/ratio), it is no surprise that your slightly longer FPL51-flavoured telescope has better performances that its shorter FPL53-blessed sibling.
And, no, the Starwave 102 f/11 is not at all an exception; it is simply a relatively widespread instrument which uses just some of the above-mentioned design elements. That's why more people experience the phenomenon and therefore talk about it.
But I can tell you that, just to pick up but a few, the well-mated TMB-designed 110 f/7 WO-branded FPL51-flavoured triplet has the same correction (if not better) than the AP Traveler FPL53-based triplet (not at all bashing AP -- I own them; just being realistic). Yes, of course the Traveler is f/5.8 and much more portable as it is (although the WO can be split into 3 parts, while the Traveler only in 2). Further, the very same can be said of the old AT 111 f/7. And shall we talk about the WO 110 f/6.5 oiled version made by TEC...?! And, to remain in TEC domain -- not because TEC is magic, but because Yuri did his homework and carries out some clever mating -- I can tell you that the FPL51-doomed TEC200ED f/9 has a better color correction of both my C11 and C14 that, at high magnification, show the spurious colour (and spherochromatism) coming from their Schmidt plate. And, had Yuri done a f/10 version of this ED, this would have been pure white at the CCD at 486nm, even better than his f/8 CaF2 (Fluorite) sibling.
So, no magic: optics (or, better, opto-mechanics). And clever execution of it.
PS/ All this being said, for an astro-photographer the spherical has very little importance, while the chroma correction WITH as fast as possible focal ratio has. Therefore, today astrophotography-driven market does heavily favour -- and therefore put a heavy pride-of-ownership value on -- the short-focus FPL53-blessed instruments, and rightly so for that purpose. But if you are instead into, say, visual planetary, your FPL51-plagued telescope, with a slightly longer f/ratio (between 25 and 50%, depending on whether the designer was heavenly inspired or just a mere stray dog) will serve you and your eyepieces much better.
Edited by Max Lattanzi, 22 March 2021 - 06:55 PM.