CAL Imagery wrote in post #15941466
I must've gotten a good copy, because the 1-4 I rented last summer was very nice. I'd highly recommend that copy for what it does.
My 100-400 is a fantastic performer, too; however, what Wilt is referring to is the MTF charts that measure resolution of lenses. And, by the numbers in those, the 100-400 is significantly duller than, say, the 400 f/5.6.
With MTF charts, though, you're talking about numbers that have every chance of not being applicable to the real-world scenarios you may find yourself shooting in. It's sort of like worrying about a car that has a top speed of 140mph and one with a top speed of 200mph. Sure, one is clearly faster than the other, but how often are you going to even hit 140 in either car.
Roger Cicala, over at LensRentals, has an interesting article related to this: http://www.lensrentals.com …have-you-seen-my-acutance
Luminous Landscape also has a very good writeup, that even includes an MTF comparison of the 100-400 and 400 f/5.6, coincidentally.
One of the important things to note in that article is the point about:
"Canon's MTF charts are based on theoretical calculations used in the design of the lens, while some other manufacturers use actually measurements. There are valid arguments in favour of both methods. Be aware though that different manufacturers have different measurement procedures, and therefore while comparing MTF charts between lenses in the same line is possible, and is in fact very useful in making a purchasing decision, doing so between different manufacturer's MTF charts isn't."
So, while MTF charts give us SOME information, they're not the be all/end all of information about how a lens may perform.