tu jest jasno napisane że extendery bedą dziłały szybciej ale tylko z nowymi seriami ( II IS ) supertele:

....Each extender also features a newly developed microcomputer that increases AF precision when the extenders are used with a IS Series II EF super-telephoto lens....

http://www.the-digital-picture.com/P...ouncement.aspx

Tak wiec sorry Winnetou...