Quote Originally Posted by Bombsight


Canon 100-400 L


I wish I could afford a 1Ds MKIII so I could use a 2x with auto focus.
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AFAIK, even a 1-series can't autofocus the 100-400 with a 2x. Natively the lens is f/4.5-5.6, so with a 1.4 it becomes f/6.3-8, and f/8 is the limit of AF on the 1D/1Ds. F/5.6 is the limit on all other bodies if I remember correctly.