When comparing the ISO 12233 charts of the Canon EF 70-200mm f/4.0 L USM and the Canon EF 70-200mm f/4.0 L IS USM the non IS version shows very soft corners and CA at 70mm f/4. What is your experience with this lens at 70mm f/4.0 - f/5.6? Is it really as bad as the ISO charts show? Canon's MTF charts show much less of a difference between the two lenses. Could there have been a problem with the lens used for the review?
