Originally Posted by jaapv
The CA is the Canon, not the lens. It is a full Achromat and thus does not have perceptible chromatic aberration. Full frame sensors are problematic, even on a DSLR.
That's been my experience as well. I have the 400/6.8 and have used it on someone's 5D and my 20D. There was significant CA with the 5D, little to none on the 20D. I found that with numerous other lenses too, one reason I stuck with the 20D and bought an ultrawide zoom to make up the short end, rather than buying a 5D.