In this modern age, it's ridiculous there should be so much confusion about the 'real' performance of lenses, resulting in a situation where the fastidious consumer feels compelled to test lenses before buying.
That might be nice in lolipop wonderland, but it's not going to happen, I don't think, anytime during our stay on the planet.
It seems like a lot of folks, in this "immediate gratification" day and age where one can get cash out of an ATM, a meal from a drive through and shop online all within the time span of ten minutes (or less, depending on the # of brain cells functioning in your friendly local fast food workers noggin when he takes your order) want a simple "grade" or number that tells us, is perfect, and can thus be used as the "final answer" as to which lens (or camera system, etc) is better but in reality that can't happen.
In terms of lenses - MTF graphs have their use, but they really can't be compared between manufacturers, and then again they don't always tell us how a lens performs in that pesky thing called "the real world". Lenses are balancing acts - and there is more than just sharpness to the equation. A lot of people, particularly in the forums, seem to have sharpness as the only attribute of lens quality that matters, when there is actually quite a bit more. I don't personally believe any one lens design firm, whether it be Zeiss, Sony, Nikon, Canon, Pentax, Olympus etc has automatic and immediate superiority over the other brands in the same manner than Kenyan marathoners seem to kick everyone else's backsides in marathons - each firm has different objectives and philosophy, and I'm sure if you all went to each one of them and said "design me the sharpest lens and I don't care if it sucks at every other aspect of lens performance" they could end up with lenses that are actually rather similar. If you take a look at the Sony MTF's, you will see some family resemblance - like Nikon, they tend to like a contrasty lens, and they also seem to want to emphasize center sharpness over other aspects - at times you'll see more spread between the sagittal and tangential plots versus, say, Nikon for a similar lens, which may (or may not, being MTF is not a perfect indicator) indicate the Sony may have the very slightest edge in resolution here and there but maybe not do so well in bokeh or tonal transitions - there are tradeoffs in every design, and each company has their own philosophy how to do it, and most of us who are "into" lenses likely eventually has their own tastes somewhat aligned with what the manufacturer we have chosen's balance. (I'm, for instance, a Nikon lens fan - I do prefer Nikon glass in general over Canon and most of the Zeiss stuff, and there are others who likely feel the opposite, and we do so more more for the rendering differences as opposed to how the lenses test on a chart or how much sharpness they have.)
So there's really no way to test for that - and on top of that, lenses are often designed to task - certain things are "given up" to gain something else in an area that matches a task - so there's no really good way for a single "lens grade" to indicate that either, much to the dismay of the folks who can't handle the reality that subjective evaluation is neccessary for lens selection.
(we could go into tons of other factors - some lenses are better at distance, some better at closer range, some balanced - are you going to have 30 scores for a set of attributes in order for us to arrive at a conclusion? And then again, how are you going to test all of that?)
So at the end of the day, it's guys like Mark Welsh (on the canon centric side) and guys like Bjorn Rorslett (on the Nikon side) and personal evaulation that ultimately lets me know if a lens is going to cut it for what *I* do - no single MTF graph or brand zealot trumpeting some chart is going to tell me what I need to know.
As far as the original thread goes, my contribution is thus (and I'm likely going to get some "heat" for this as here is where I get opinionated...)
* The way I see the industry, I currently only see two manufacturers dealing with the lens demands of FF bodies at the current time - Nikon and Sony. Witness the performance of the very latest Nikon zooms and the reviews on the Sony 24-70 and I think an argument can be made that while Canon took the FF route of making the camera bodies and sensors first, but perhaps leaving themselves a bit "short" in terms of ultimate lens quality for the highest resolving sensors, Nikon and Sony are taking the opposite approach - introducing very high performance lenses first and then the bodies will come later. Note that while most of you out there (who likely shoot Canon - let's be honest here - this is a very heavy Canon oriented site) are ready to skewer me in argument, I seriously don't think Canon is going to sit on the sidelines and not do anything about it - likely they will to introduce lenses in areas where they've traditionally been weak (wide zooms, etc) in order to fully utilize what their sensors are capable of - but as of now, Sony and Nikon are addressing this first. Which is good - it puts pressure on Canon and that's not a bad thing.
* related to the above, I see that quite soon, once the major players have hi-rez FF bodies available, that lens sharpness will just simply HAVE to be really good - and while maybe one might be a smidge better than the other, we may arrive at a time where ANY of the best lenses from any of the brands will most definitely be professionally sharp and quite excellent.
* The hurdle for Sony becoming a pro player is going to be related to two things (watch out, I'm going to get negative here)..
* Minolta bodies have been historically substandard. Sorry - in 30 years of photography I've seen/heard/witnesses more problems with Minolta gear than I ever have with Nikon, Canon, Pentax or Olympus. My own brief experience with Minolta left me with a sour taste as well. I'd happily use any of the other systems out there (well, not Olympus, but that's because 4/3rd is a dying game, but their bodies outside of that are ok) but I'd absolutely NEVER use a Minolta body, no matter what name is on it. (Interestingly, when I started out in the mid 70's, it was the same thing then - most of the pro's I talked to LOVED Rokkor-X glass, but none of them would touch a Minolta body with a 10 foot pole if they needed reliability and gear they could count on when the going got tough.)
* To be a pro player, one needs a FULL line of lenses, and only two players have that right now - Canon and Nikon. Sony has a ways to go to catch up.
Sony probably can get the support aspect settled - they have decently deep pockets, but I'd have to see a fully fleshed out lens line and a good 5-6 year period where their bodies are in use by pro's - not just by the twice a year landscape serious amateur, but by a large contingent of pros - before I'd consider them ready for the pro game. I personally don't see it happening, but hey, I'll absolutely eat my words if I'm proven wrong.
Enough controversy for today - back to lurk mode I go