Also Roger tests multiple copies of lenses and his lenses are normal retail lenses. I am always suspicious of lens tests where the manufacturer sends the tester 1 copy of the lens.... odds are that the 1 lens is cherry picked and is not representative of a typical lens....I realize that I'm replying to an old post that's part of an old thread with recent activity due to the high mp alleged confirmation by Canon.
I wanted to address one thing in particular though. I question the assumption that recent lenses and mk ii lenses are being refreshed for higher mp sensors, including current aps-c 18mp crop sensors.
I was wondering earlier how the current EF 70-200mm f/2.8 IS II USM would perform on a higher mp camera, so I tried looking up its resolving power in lp/mm and ran across a review I hadn't read before, by DxOMark stating that for that particular lens its predecessor, the original EF 70-200 f/2.8 IS USM (mk I) had more resolving power. Then in the comments, they stated that it was sharper on aps-c bodies than it is on ff bodies (which I didn't understand). I've not read any other review that made such claims.
Then I decided to look into the new 100-400mm zoom mk II and read that more or less it has about the same resolving power as its predecessor, and the true improvement is in the stabilization upgrade/update. Was it already resolving well enough before? I've never used one, so I don't know.
Any thoughts on this. I am aware that many here are not fans of DxOMark and their results, but the 100-400 II still has me scratching my head.
Well, your relying on DXO. Guess that's enough said.
One thing I will say is, older Canon lenses often resolved very well in the center, and very poorly in the corners. For film, where huge enlargements were not as common (most of the time, it was smaller enlargements or contact prints, so maybe 8x10 tops on average), poorer corners were probably not as much of a problem. Newer Canon lenses and the Mark III TCs have all been addressing corner performance. Some of Canon's newer lenses did not improve center or midframe resolution much...but improved corner resolution a ton. Some lenses, like many of the new Great White Mark II generation, improved resolving power across the board.
For the best lens resolution tests around, check out Roger Cicala's LensRentals blog. He regularly tests new lenses, using an optical test bench (so he's testing LENSES, not camera systems), and his comparisons tend to be more accurate and generic than most. None of this "limited by the sensor" crap that skews and convolutes results.