How much did lens quality improve over EF mount's lifetime?

Machinus wrote:

I can tell that newer EF lenses are sharper than older ones, along with being lighter, etc. I have read lots of other assessments that agree with that opinion, for most lenses. This sounds obvious, especially for lenses with revisions. I was wondering if this had been quantitatively compared by someone with good optical tools and access to a variety of lenses from the EF line, but I couldn't find the kind of study I am looking for.

It really depends on what specific you are looking at in a lens, and a bit on when you define the EF era's beginning.

No one can argue that the Sigma 50mm F/1.4 ART is not miles better than a nifty fifty or even the early 50mm EF 1.4.

Wide angle Zooms have improved markedly, long Zooms and long lenses (>300mm) have not improved as much a lot of which is that they stated out so close to superb that there was little to improve upon.

For example, how do the most recently produced 70-200s compare to the older 200Ls, even more expensive ones? Would a new 2.8 beat an old 2 or 1.8? Or, how does the image quality of the rare 1200mm compare to a 600mm, produced 25 years later, with a 2x extender? I think it would be interesting to see how much Canon improved their lensmaking technique over decades on the same mount. Now that there are no more new EFs to test, you could make a definitive conclusion about the evolution of the entire mount.

70-200 have seen incremental improvements and available in differing maximum apertures and whether IS is present. I have a 1980s Vivitar lens that still works acceptably well, and I was shocked when I bought it (new) that it was as competent as it ended up being. Shot a lot of film with that one.