As good as it gets?

Ktrphoto wrote:

Extremely sharp and detailed results

Corner sharpness not too different from centre

Very little light fall off in the corners

Completely usable at f/4

Aberrations and distortion so little as to be no problem

Attractive Bokeh at long focal lengths and wide apertures

Super fast and accurate AF

Internal focussing - no extension, no rotating front element

Beautiful zoom ring (90 degrees of turn, light enough to work with one gentle finger, but no zoom creep

Does not extend on zooming

Results with 1.4x extender as good (for all practical purposes) as with the bare lens [Have not yet tried the 2x]

USM - so can manually focus without messing around with switches and buttons to disable AF

Extremely effective Image Stabilisation

Is not prone to flare

Very tough construction

Sealed against dust and moisture

Considering what you are getting, it is not too big and not so heavy

I never knew lenses could be this good. It is close to perfect ... or a least, as good as it can get.

It's very hard to fault if you want a 70-200 f/4. The long thin shape makes it difficult to fit in many bags - that's about all I can think of.

However I agree with those who are saying that f/4 is its weakness. I know that's a bit like saying the problem with a 1lb bag of sugar is that it doesn't have 2lb of sugar in it, but when you look at the main applications for a 70-200 lens they tend to be things which benefit greatly from an f/2.8 aperture so an f/4 lens will always be second best.

Or if you want it as a general purpose tele zoom, rather than a specialist lens for sports say, or portraits, then 200 mm is often not long enough and the 70-300L starts to look like a more attractive choice.